Stretch 0.5sec pulse to 6sec

On Mon, 04 Feb 2013 16:49:29 -0600, Tim Wescott <tim@seemywebsite.com>
wrote:

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
tim@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <amdx@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.


The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip. You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.

Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

I don't believe what's printed. Drawing lines outside what's printed
is suicidal.

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

555s are designed to work with much higher resistors. The '123 really
isn't very good.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

Use a PIC. ;-)

 

[Tim Wescott]

On Sun, 03 Feb 2013 11:02:01 -0600, amdx wrote:

On 2/2/2013 8:42 PM, Jamie wrote:
amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse that
will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.


|
===
GND
.-.
| |1MEG PTT load (Radio)
| | |
0.5s Pulse 1k '-' ||-+
___ | ||<-
-|___|-->|+-------+-+-----------+-||-+
+ |
1N914 + |
--- 10uf ===
--- GND
+
| Power NMOS or what ever
|
===
GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Depending on your Vgs(th) spec you use for the NMOS will determine
the time off delay, which is what I think you're after.

This is one should be ~ 5 to 6 secs.

I didn't do a sim on this, just used a calculator but it should be
close.
THe pulse should pull the output down fast and the off delay
will give you a slight ramp due to the way fets are biased and behave
when the drain starts to get higher in voltage than the gate. This
should work out.

The diode is there to prevent back drain from the pulse source.

Jamie


Thanks Jamie,
That seems to be working well. I have it breadboarded using 500k and
47uf with an IRFBE30* MOSFET, because that's what I have.
I'll work with it a bit more to get me centered between 2 alerts and 4
alerts. Right now it is alerting 3 times but I don't know if it is
centered between 2 and 4 alerts.
This will fit better in the case.
Thanks again, Mikek

Went back to the bench with a 1 meg pot, Found two alerts at 344k and 4
at 513k, centered at 428k and it consistently alerts 3 times. (47uf)


* IRFBE30 800V 30amp 3 ohm on resistance. Overkill but I have it.

You will find this to be far more temperature sensitive than a 555 or a
74HC123, and while it's probably not as important in your case, far more
sensitive to part variations.

You'll also find that the PTT load does not switch immediately -- it's
going to go down slowly as the gate lead voltage goes up slowly. It's
also going to be subject to external interference as the gate lead
voltage goes up through threshold.

Putting in some positive feedback into your MOSFET circuit would help
that, but would require enough more components that you may as well use
some dedicated chip.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

 

[Fred Bartoli]

Tim Wescott a ĂŠcrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
tim@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <amdx@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.


The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!
74<your choice>123

Nice chip. You choose between positive- and negative-going pulses
in and out.
Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.
I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)
Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.
It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)


--
Thanks,
Fred.

 

[amdx]

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.

I had the 555 circuit breadboarded, it worked.
I'm sure a 74123 could work.
A CD4060 and a dual J-K flip-flop could work.
A pic would work.

But Jamie's circuit worked with 5 parts, I had on hand.

Check with my 6 months from now, if it still works, ya'll can call it
a success.
I'm calling it now.

For Jim,
Alert, Alert, Alert.
That's what it does now.
Alert, Alert, Alert.

Thanks, Mikek

 

[George Herold]

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :





On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

   I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

   Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
    The 2N3904 switch is across the alert button on a Walkie Talkie
    and
shorts about 3.5v to ground.

The longer story;
   This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
   That is to much, three times is fine. After trying several
   things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!
74<your choice>123

Nice chip.  You choose between positive- and negative-going pulses
in and out.
Not so great with that kind of delay.

 Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
 Bonus, I had all the parts.
  I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.
I'll bet even DigiKey (via UPS) ships to that end of the line.  ;-)
Six seconds.  Hmm.  Good point.  Of course, nothing that's RC-based is
going to really be solid at that delay.  For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.
It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI.  This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage.  The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity.  Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

 

[John Fields]

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
<tim@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <amdx@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.


The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor.
The sensor triggers a receiver with RF.
The receiver in turn triggers the alert button on a **Walkie Talkie.
After a temporary install, I noted the Talkie alert signaled 10
times.
That is to much, three times is fine.
After trying several things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll deal
with this later by putting the Harbor Freight receiver inside my boat
and the walkie talkie outside where it's RF can get out. (it's an all
Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse causes
three alert signals. Perfect!

74<your choice>123

Nice chip. You choose between positive- and negative-going pulses in
and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.

Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

---
A '4538

http://www.ti.com/lit/ds/symlink/cd54hc4538.pdf

has the same functionality as a '123, but leakage on the RC input is
only 50nA @ 25C, so 6 seconds is no problem.
_
Also, for a bonus, the A and B inputs are Schmitt triggered.

--
JF

 

[Fred Bartoli]

George Herold a écrit :

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:
Tim Wescott a écrit :





On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:
On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:
On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:
On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:
On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:
I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.
I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.
Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.
The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.
I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!
74<your choice>123
Nice chip. You choose between positive- and negative-going pulses
in and out.
Not so great with that kind of delay.
Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.
I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)
Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.
It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.
So extend the charts!!
The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.
Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.
I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.
I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

I just mentioned jameco because the OP seems to be an hobbyist, but have
a look at the datasheet. It's a pretty interesting son of a ...555

--
Thanks,
Fred.

 

[John Fields]

On Sat, 02 Feb 2013 17:21:40 -0600, amdx <amdx@knologynotthis.net>
wrote:

I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.

---
View using a fixed-pitch font:
WALKIE-TALKIE
Vcc-----------------------+-------+ +-------------+
| | | Vbat+ |
[R] | | | |
| | | [R] |
0.5S>--[1N4148>]--+---+---|----+-|-\U1A | | |
| | | | | >-+-->|>--+ |
| | +--+-|-|+/ | | | |
| | | | | | | O | |
| | | | | | | |<-PTT |
[Rt][Ct] | | | | | O | |
| | [R] | +-|-\ | | | |
| | | | | >-+ | | |
| | | +---|+/U1B | +--Vbat- |
| | | |LM393 | | |
GND>--------------+---+---+-------+------>|>--+ |
+-------------+

--
JF

 

[John Fields]

On Tue, 05 Feb 2013 03:48:58 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx <amdx@knologynotthis.net
wrote:

I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.

---
View using a fixed-pitch font:
WALKIE-TALKIE
Vcc-----------------------+-------+ +-------------+
| | | Vbat+ |
[R] | | | |
| | | [R] |
0.5S>--[1N4148>]--+---+---|----+-|-\U1A | | |
| | | | | >-+-->|>--+ |
| | +--+-|-|+/ | | | |
| | | | | | | O | |
| | | | | | | |<-PTT |
[Rt][Ct] | | | | | O | |
| | [R] | +-|-\ | | | |
| | | | | >-+ | | |
| | | +---|+/U1B | +--Vbat- |
| | | |LM393 | | |
GND>--------------+---+---+-------+------>|>--+ |
+-------------+

---
Just for fun, how to get a long delay with a small cap:

Version 4
SHEET 1 880 680
WIRE 352 16 352 -16
WIRE 544 16 544 -16
WIRE 416 112 416 96
WIRE 384 128 320 128
WIRE 544 144 544 96
WIRE 544 144 448 144
WIRE 352 160 352 96
WIRE 384 160 352 160
WIRE 416 192 416 176
WIRE 416 288 416 272
WIRE 48 304 -16 304
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WIRE 544 320 544 144
WIRE 544 320 448 320
WIRE -16 336 -16 304
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WIRE 384 336 352 336
WIRE 144 368 144 304
WIRE 256 368 256 304
WIRE 416 368 416 352
WIRE 352 400 352 336
WIRE -192 432 -192 416
WIRE -112 432 -112 416
WIRE -16 432 -16 416
WIRE -192 544 -192 512
WIRE -112 544 -112 512
WIRE -112 544 -192 544
WIRE -16 544 -16 512
WIRE -16 544 -112 544
WIRE 144 544 144 448
WIRE 144 544 -16 544
WIRE 256 544 256 432
WIRE 256 544 144 544
WIRE 352 544 352 480
WIRE 352 544 256 544
WIRE 384 544 352 544
WIRE -192 592 -192 544
FLAG -192 592 0
FLAG 384 544 0V
FLAG 416 368 0V
FLAG 416 192 0V
FLAG -192 416 +5
FLAG -112 416 3.5
FLAG 352 -16 +5
FLAG 416 272 +5
FLAG 416 96 +5
FLAG 544 -16 3.5
SYMBOL res 128 352 R0
SYMATTR InstName R1
SYMATTR Value 10meg
SYMBOL cap 240 368 R0
SYMATTR InstName C1
SYMATTR Value 270n
SYMBOL Comparators\\LT1017 416 144 R0
SYMATTR InstName U1
SYMBOL Comparators\\LT1017 416 320 R0
SYMATTR InstName U2
SYMBOL res 336 0 R0
WINDOW 0 -46 41 Left 2
WINDOW 3 -60 70 Left 2
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL res 336 384 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL diode 48 320 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL voltage -16 416 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value PULSE(0 5 .1 1u 1u .5)
SYMBOL voltage -192 416 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL res -32 320 R0
SYMATTR InstName R4
SYMATTR Value 400
SYMBOL voltage -112 416 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value 3.5
SYMBOL res 528 0 R0
SYMATTR InstName R5
SYMATTR Value 1000
TEXT -184 568 Left 2 !.tran 10 startup uic

--
JF

 

[Jim Thompson]

On Mon, 04 Feb 2013 11:29:46 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx <amdx@knologynotthis.net
wrote:

I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.


The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor.
The sensor triggers a receiver with RF.
The receiver in turn triggers the alert button on a **Walkie Talkie.
After a temporary install, I noted the Talkie alert signaled 10 times.
That is to much, three times is fine.
After trying several things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll deal
with this later by putting the Harbor Freight receiver inside my boat
and the walkie talkie outside where it's RF can get out. (it's an all
Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse causes
three alert signals. Perfect!


*
http://www.harborfreight.com/wireless-driveway-alert-system-93068.html

**
http://www.motorola.com/Business/US-EN/Business+Product+and+Services/Two-Way+Radios+-+Consumers/Talkabout+FV300+Two-Way+Radio_B2B_US_EN

Mikek

Sort of an off-the-wall thought...

Count the 'lerts >:-}

...Jim Thompson

What I was musing over...

Your pulse sets a flop, the flop applies the drive to the 3904.

"Listen" to three alerts, then reset the flop.

No timer required. No TC's. No critical time matching to ensure only
three 'lerts.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[George Herold]

On Feb 5, 4:43 am, Fred Bartoli <" "> wrote:

George Herold a écrit :





On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:
Tim Wescott a écrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:
On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:
On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:
On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:
On 2/3/2013 6:35 PM, Tim Wescott wrote:
On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:
I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.
   I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.
   Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
    The 2N3904 switch is across the alert button on a Walkie Talkie
    and
shorts about 3.5v to ground.
The longer story;
   This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.
I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
   That is to much, three times is fine. After trying several
   things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out..
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!
74<your choice>123
Nice chip.  You choose between positive- and negative-going pulses
in and out.
Not so great with that kind of delay.
 Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
 Bonus, I had all the parts.
  I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.
I'll bet even DigiKey (via UPS) ships to that end of the line.  ;-)
Six seconds.  Hmm.  Good point.  Of course, nothing that's RC-based is
going to really be solid at that delay.  For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.
It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI.  This sort of thing is right up the alley for
a 555, though.
So extend the charts!!
The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage.  The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.
Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity.  Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.
I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.
I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

I just mentioned jameco because the OP seems to be an hobbyist, but have
a look at the datasheet. It's a pretty interesting son of a ...555

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

No problem Fred, I use to buy lots of things from Jameco.
That is an interesting part. low voltage and an internal eeprom
controlled divider.

George H.

 

[Jamie]

George Herold wrote:

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :






On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.

The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip. You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -


I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

I remember having a few of those too, and the voltages were all over
the place. I don't remember where I got them from but it would appear to
me they may have been seconds that I got from some surplus dealer.

Sometimes you never know.


Jamie

 

[Jamie]

Fred Bartoli wrote:

George Herold a écrit :

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :





On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.
I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh
yes I
could probably differentiate the 0.5 sec pulse to trigger the
555,
so maybe only 1 transistor and a 555.
Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie
Talkie
and
shorts about 3.5v to ground.
The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean
power.
I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert
button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver
inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123
Nice chip. You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We
are at
the end of the line. Nothing goes past us to get somewhere. I
have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's
RC-based is
going to really be solid at that delay. For what he wants,
though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC
types,
at least according to TI. This sort of thing is right up the alley
for
a 555, though.

So extend the charts!!
The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and
output.
Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had
done
something with a counter from the git-go, and build your circuit.
I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd
have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -


I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.


I just mentioned jameco because the OP seems to be an hobbyist, but have
a look at the datasheet. It's a pretty interesting son of a ...555

The timer has been one of the most versatile IC's made that i've
worked with. I've used that for various applications including those
that had nothing to do with timing but to do with using the Trigger and
threshold as window comparators, one time even trigger latch,etc...

The Cmos version brings an interesting batch of applications with it
since it can operate on a single cell. THe ICM7555 Cmos timer is an
interesting package, too.

Jamie

 

[Jamie]

John Fields wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx <amdx@knologynotthis.net
wrote:


I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.


---
View using a fixed-pitch font:
WALKIE-TALKIE
Vcc-----------------------+-------+ +-------------+
| | | Vbat+ |
[R] | | | |
| | | [R] |
0.5S>--[1N4148>]--+---+---|----+-|-\U1A | | |
| | | | | >-+-->|>--+ |
| | +--+-|-|+/ | | | |
| | | | | | | O | |
| | | | | | | |<-PTT |
[Rt][Ct] | | | | | O | |
| | [R] | +-|-\ | | | |
| | | | | >-+ | | |
| | | +---|+/U1B | +--Vbat- |
| | | |LM393 | | |
GND>--------------+---+---+-------+------>|>--+ |
+-------------+

555 Inverted PTT, non resetable


.---------------.
| |
| 4V TX SIG > -----THRESHOLD |
=== | |
GND | |
--- | |
--- | |
|---+---+------+----TRIG |
.-. + | |
| | - | |
| | ^ | |
'-' + |OUT |
+---+---+------+---- Discg ---------- PTT LINE
| |
| |
VCC | |
-+ |Vcc |
|---- |
5 VOLTS | | RESET |
| '--|---------|--'
| | |
| | |
| + |
+------+ GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Try this one. I see yours work but it has more parts than this one
does and this is non-resetable, which means the first pulse will
set it to exactly what time window is needed with out any other
pulses resetting the time constant before expiration.

Now It could be that the resetting of the time constant before
expiration of the 6 seconds maybe more desirable but with this one,
the first pulse will start it and any remaining pulses will be ignored
with in the time frame.

Jamie

 

[George Herold]

On Feb 5, 6:20 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

George Herold wrote:
On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

  I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

  Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
   The 2N3904 switch is across the alert button on a Walkie Talkie
   and
shorts about 3.5v to ground.

The longer story;
  This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
  That is to much, three times is fine. After trying several
  things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip.  You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
 I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts..

I'll bet even DigiKey (via UPS) ships to that end of the line.  ;-)

Six seconds.  Hmm.  Good point.  Of course, nothing that's RC-based is
going to really be solid at that delay.  For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI.  This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage.  The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity.  Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

  I remember having a few of those too, and the voltages were all over
the place. I don't remember where I got them from but it would appear to
me they may have been seconds that I got from some surplus dealer.

  Sometimes you never know.

Jamie- Hide quoted text -

- Show quoted text -

These had a problem with turn on. Sometimes V+ would turn on before
V- and then sometimes the 7912 would *not* turn on. PITA, when it only
doesn't work sometimes. I was pulling out my hair, until my boss
suggested ordering new parts. No problems since then.... Well, not
the same problem anyway.

George H.

 

[Phil Hobbs]

On 2/5/2013 10:29 PM, George Herold wrote:

On Feb 5, 6:20 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
George Herold wrote:
On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.

The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip. You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

I remember having a few of those too, and the voltages were all over
the place. I don't remember where I got them from but it would appear to
me they may have been seconds that I got from some surplus dealer.

Sometimes you never know.

Jamie- Hide quoted text -

- Show quoted text -

These had a problem with turn on. Sometimes V+ would turn on before
V- and then sometimes the 7912 would *not* turn on. PITA, when it only
doesn't work sometimes. I was pulling out my hair, until my boss
suggested ordering new parts. No problems since then.... Well, not
the same problem anyway.

George H.

Some, perhaps all, 7800 series regulators won't start up if you pull the
output below ground.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[Jamie]

George Herold wrote:

On Feb 5, 6:20 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

George Herold wrote:

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie
and
shorts about 3.5v to ground.

The longer story;
This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
That is to much, three times is fine. After trying several
things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip. You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line. ;-)

Six seconds. Hmm. Good point. Of course, nothing that's RC-based is
going to really be solid at that delay. For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI. This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage. The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity. Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

I remember having a few of those too, and the voltages were all over
the place. I don't remember where I got them from but it would appear to
me they may have been seconds that I got from some surplus dealer.

Sometimes you never know.

Jamie- Hide quoted text -

- Show quoted text -


These had a problem with turn on. Sometimes V+ would turn on before
V- and then sometimes the 7912 would *not* turn on. PITA, when it only
doesn't work sometimes. I was pulling out my hair, until my boss
suggested ordering new parts. No problems since then.... Well, not
the same problem anyway.

George H.
Never had that problem, sounds like protection coming in too soon do

to inrush from the caps.

You must remember when those were originally made, ESR worries wasn't
so much the rave as they are today. Crappie high ESR caps most likely
would work just fine if that is the issue.

Jamie

 

[George Herold]

On Feb 6, 9:41 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

George Herold wrote:
On Feb 5, 6:20 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

George Herold wrote:

On Feb 4, 6:05 pm, Fred Bartoli <" "> wrote:

Tim Wescott a écrit :

On Mon, 04 Feb 2013 12:36:38 -0500, krw wrote:

On Sun, 03 Feb 2013 22:08:20 -0600, Tim Wescott
t...@seemywebsite.please> wrote:

On Sun, 03 Feb 2013 20:32:05 -0500, krw wrote:

On Sun, 03 Feb 2013 19:25:55 -0600, amdx <a...@knologynotthis.net
wrote:

On 2/3/2013 6:35 PM, Tim Wescott wrote:

On Sat, 02 Feb 2013 17:21:40 -0600, amdx wrote:

I have a 4 volt pulse that is 0.5 sec long. I need a 6 sec pulse
that will switch a 2n3904. The 4 volts has about a 400 ohm source
impedance.

 I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555,
so maybe only 1 transistor and a 555.

 Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819,
probably a diode. That will drive my final 2N3904 switch.
  The 2N3904 switch is across the alert button on a Walkie Talkie
  and
shorts about 3.5v to ground.

The longer story;
 This started with "Have 5v regulator need 9 volts"
That particular problem is solved. everything has good clean power.

I have a Harbor Freight *Driveway sensor. The sensor triggers a
receiver with RF. The receiver in turn triggers the alert button on
a **Walkie Talkie. After a temporary install, I noted the Talkie
alert signaled 10 times.
 That is to much, three times is fine. After trying several
 things to eliminate the 10 alerts, I finally
wrapped the walkie talkie in aluminum foil. Problem solved. I'll
deal with this later by putting the Harbor Freight receiver inside
my boat and the walkie talkie outside where it's RF can get out.
(it's an all Aluminum boat)
The 0.5 sec pulse causes one alert signal. A six second pulse
causes three alert signals. Perfect!

74<your choice>123

Nice chip.  You choose between positive- and negative-going pulses
in and out.

Not so great with that kind of delay.

Jamie's RC, power FET circuit worked good and fit easily, no power
supply needed, only 5 parts.
Bonus, I had all the parts.
I'm in Panama City Fl. The highway doesn't make it here. We are at
the end of the line. Nothing goes past us to get somewhere. I have a
radio Shack and a one man audio repair shop, that sells some parts.

I'll bet even DigiKey (via UPS) ships to that end of the line.  ;-)

Six seconds.  Hmm.  Good point.  Of course, nothing that's RC-based is
going to really be solid at that delay.  For what he wants, though, any
halfway decent approximation to six seconds ought to be OK.

It's way off (three orders of magnitude off) the chart for the HC types,
at least according to TI.  This sort of thing is right up the alley for
a 555, though.

So extend the charts!!

The delay time of a 74HC123 is roughly one RC time constant, you don't
want the resistance to be too low and if it gets too high then you have
to contend with board or capacitor leakage.  The delay time of a 555 is
roughly the same, but you don't have the flexibility of input and output.

Either chip demands that you select a big, low-leakage cap, and a high
resistance, and accept the fact that your leakage is going to vary with
temperature and humidity.  Understand that you'll wish that you had done
something with a counter from the git-go, and build your circuit.

I _think_ you could do this more reliably with a CD4060 and a dual J-K
flip-flop, or a 555, a CD4040, and that same J-K flip-flop, but I'd have
to toy with it to be sure and I don't think I care enough to try.

I just saw a nice CSS555 (available at Jameco)

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

I stopped buying stuff from jameco after a bad batch of 79L12 voltage
regulators.... cost me too much time.

George H.

 I remember having a few of those too, and the voltages were all over
the place. I don't remember where I got them from but it would appear to
me they may have been seconds that I got from some surplus dealer.

 Sometimes you never know.

Jamie- Hide quoted text -

- Show quoted text -

These had a problem with turn on.  Sometimes V+ would turn on before
V- and then sometimes the 7912 would *not* turn on. PITA, when it only
doesn't work sometimes.  I was pulling out my hair, until my boss
suggested ordering new parts.  No problems since then.... Well, not
the same problem anyway.

George H.

  Never had that problem, sounds like protection coming in too soon do
to inrush from the caps.

   You must remember when those were originally made, ESR worries wasn't
so much the rave as they are today. Crappie high ESR caps most likely
would work just fine if that is the issue.

Jamie- Hide quoted text -

- Show quoted text -

Well in this case it was just bad parts. The same circuit has been
working of years now... I just copied whatever was in the app note/
spec sheet. Both ceramic's and tant's cap-wise. 0.1 of this, 10uf of
that.

George H.

 

[Ian Field]

"amdx" <amdx@knologynotthis.net> wrote in message
news:f1f41$510dbf2b$18ec6dd7$13750@KNOLOGY.NET...

On 2/2/2013 5:21 PM, amdx wrote:
I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.


I have breadboarded the two transistor, 555 circuit.
Three alert signals as wanted. I can wire it on a pcb
in the morning, if no one comes up with a simple RC one transistor
pulse stretcher. I couldn't make it work, maybe it can't be done.

There *ARE* various pulse stretcher circuits on the web if you look.

 

[Ian Field]

"amdx" <amdx@knology.net> wrote in message
news:e0476$510e7a0a$18d6b405$27119@KNOLOGY.NET...

On 2/2/2013 7:38 PM, Jasen Betts wrote:
On 2013-02-02, amdx <amdx@knologynotthis.net> wrote:
I have a 4 volt pulse that is 0.5 sec long.
I need a 6 sec pulse that will switch a 2n3904.
The 4 volts has about a 400 ohm source impedance.

I could use a 555, but first I need to invert the signal then
drive my 2n3904 switch, so I have 2 transistors and a 555. Oh yes I
could probably differentiate the 0.5 sec pulse to trigger the 555, so
maybe only 1 transistor and a 555.

Could someone help with a pulse stretcher circuit.
Maybe an RC, transistor, or, I have some FETs, J301 or 2N3819, probably
a diode. That will drive my final 2N3904 switch.
The 2N3904 switch is across the alert button on a Walkie Talkie and
shorts about 3.5v to ground.

you can't just use the discharge pin of the 555 instead of the collector
of the
2n2904? is 200mA not enough?


Do you mean the discharge (pin 2) or output (pin 3).
The pin from the walkie talkie already has a voltage on
it, pin 3 will source current to the walkie talkie before
it sinks current. I need an open collector to pull the Walkie talkie low.
That's my understanding for now.
Mikek

Pins 3 & 7 switch in the same phase, so if you can arrange your monostable
timing circuit to use pin 3 - pin 7 is available as an open collector
switch.

I think you need a diode so pin 3 can pull the timing circuit down but not
up.