Looking for a circuit to

[Nikki]

Can I use a 555 timer somehow to do this
I have a set of those contacts that go on a door or window (there normally
open) and then when you open the window or door the contacts will close. I
need a circuit that will deliver a momentary closer for about one second
even though the window contacts remain closed. Then reset when the door or
window is closed.
Thanks Guys
Nikki

 

[Robert C Monsen]

"Nikki" <rickj@sympatico.ca> wrote in message
newsUaGc.4626$JG5.265856@news20.bellglobal.com...

Can I use a 555 timer somehow to do this
I have a set of those contacts that go on a door or window (there
normally
open) and then when you open the window or door the contacts will
close. I
need a circuit that will deliver a momentary closer for about one
second
even though the window contacts remain closed. Then reset when the
door or
window is closed.
Thanks Guys
Nikki

5V
----------+------------+---+--+-------------------------+----+---
| | | | | |
| | | | | |
| | | | .---------------. | |
.-. | .-. | | | | .-.
|R| - |R| | +----- GND Vcc ---+ |R|
|1| D1 ^ |2| | | | | |3|
'-' | '-' | | | U1 | '-'
| | | | | | | |
| || | | | | | | |
------||-----+---+--|------- Trg Dis --------+
| || | | | | |
| C1 | | | Thr --------+
| +----------------- Out | |
| | | | | | |
| | +------- Rst Ctl ---+ |
| | | | | | |
\ o | | | | | |
\ | | | | | ---
\. | | | | | ---
o | | '---------------' | | C2
| output | | |
| | | |
| | --- |
| | --- |
Gnd | | C3 | |
---------+---------------------+-----------------------+----+----

R1=1k C1=1uF D1=1N4148
R2=10k C2=10uF
R3=91k C3=0.1uF U1=TN555CN

created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

The length of the one-shot is 1.1*R3*C2. When the switch closes, the
Trg pin
is momentarily pulled low, causing the one-shot to fire, since the
right side
of C1 will try to follow the left side (which goes from 5V to 0V).
However, it
quickly charges back up to 5V due to R2.

D1 is required to protect Trg from overvoltage. However, it can be
omitted if
the 555 you use has input overvoltage protection diodes built in
(which most
cmos parts will have)

C3 is also OK to omit. If there are sensitive parts near the 555, you
might
want to put a cap between Vcc and GND, say 1uF.

Regards,
Bob Monsen

 

[Nikki]

Bob thanks for the info.
although I know a little about electronics your drawing is over my head.
Anyway you can draw it on paper and scan it.
Thanks Nikki
"Robert C Monsen" <rcsurname@comcast.net> wrote in message
news:ZtfGc.26222$MB3.18820@attbi_s04...

"Nikki" <rickj@sympatico.ca> wrote in message
newsUaGc.4626$JG5.265856@news20.bellglobal.com...
Can I use a 555 timer somehow to do this
I have a set of those contacts that go on a door or window (there
normally
open) and then when you open the window or door the contacts will
close. I
need a circuit that will deliver a momentary closer for about one
second
even though the window contacts remain closed. Then reset when the
door or
window is closed.
Thanks Guys
Nikki




5V
----------+------------+---+--+-------------------------+----+---
| | | | | |
| | | | | |
| | | | .---------------. | |
.-. | .-. | | | | .-.
|R| - |R| | +----- GND Vcc ---+ |R|
|1| D1 ^ |2| | | | | |3|
'-' | '-' | | | U1 | '-'
| | | | | | | |
| || | | | | | | |
------||-----+---+--|------- Trg Dis --------+
| || | | | | |
| C1 | | | Thr --------+
| +----------------- Out | |
| | | | | | |
| | +------- Rst Ctl ---+ |
| | | | | | |
\ o | | | | | |
\ | | | | | ---
\. | | | | | ---
o | | '---------------' | | C2
| output | | |
| | | |
| | --- |
| | --- |
Gnd | | C3 | |
---------+---------------------+-----------------------+----+----

R1=1k C1=1uF D1=1N4148
R2=10k C2=10uF
R3=91k C3=0.1uF U1=TN555CN

created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

The length of the one-shot is 1.1*R3*C2. When the switch closes, the
Trg pin
is momentarily pulled low, causing the one-shot to fire, since the
right side
of C1 will try to follow the left side (which goes from 5V to 0V).
However, it
quickly charges back up to 5V due to R2.

D1 is required to protect Trg from overvoltage. However, it can be
omitted if
the 555 you use has input overvoltage protection diodes built in
(which most
cmos parts will have)

C3 is also OK to omit. If there are sensitive parts near the 555, you
might
want to put a cap between Vcc and GND, say 1uF.

Regards,
Bob Monsen

 

[John Fields]

On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
<rcsurname@comcast.net> wrote:

5V
----------+------------+---+--+-------------------------+----+---
| | | | | |
| | | | | |
| | | | .---------------. | |
.-. | .-. | | | | .-.
|R| - |R| | +----- GND Vcc ---+ |R|
|1| D1 ^ |2| | | | | |3|
'-' | '-' | | | U1 | '-'
| | | | | | | |
| || | | | | | | |
------||-----+---+--|------- Trg Dis --------+
| || | | | | |
| C1 | | | Thr --------+
| +----------------- Out | |
| | | | | | |
| | +------- Rst Ctl ---+ |
| | | | | | |
\ o | | | | | |
\ | | | | | ---
\. | | | | | ---
o | | '---------------' | | C2
| output | | |
| | | |
| | --- |
| | --- |
Gnd | | C3 | |
---------+---------------------+-----------------------+----+----

The length of the one-shot is 1.1*R3*C2. When the switch closes, the
Trg pin
is momentarily pulled low, causing the one-shot to fire, since the
right side
of C1 will try to follow the left side (which goes from 5V to 0V).
However, it
quickly charges back up to 5V due to R2.

---
Unfortunately, because of bounce it will also fire when the switch
opens. :-(

--
John Fields

 

[Robert C Monsen]

"John Fields" <jfields@austininstruments.com> wrote in message
news:6ffle01kr2l54bosdi060g07p7hv7m145s@4ax.com...

On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
rcsurname@comcast.net> wrote:


5V

----------+------------+---+--+-------------------------+----+---
| | | | | |
| | | | | |
| | | | .---------------. | |
.-. | .-. | | | | .-.
|R| - |R| | +----- GND Vcc ---+ |R|
|1| D1 ^ |2| | | | | |3|
'-' | '-' | | | U1 | '-'
| | | | | | | |
| || | | | | | | |
------||-----+---+--|------- Trg Dis --------+
| || | | | | |
| C1 | | | Thr --------+
| +----------------- Out | |
| | | | | | |
| | +------- Rst Ctl ---+ |
| | | | | | |
\ o | | | | | |
\ | | | | | ---
\. | | | | | ---
o | | '---------------' | |
C2
| output | | |
| | | |
| | --- |
| | --- |
Gnd | | C3 | |

---------+---------------------+-----------------------+----+----

The length of the one-shot is 1.1*R3*C2. When the switch closes,
the
Trg pin
is momentarily pulled low, causing the one-shot to fire, since the
right side
of C1 will try to follow the left side (which goes from 5V to 0V).
However, it
quickly charges back up to 5V due to R2.

---
Unfortunately, because of bounce it will also fire when the switch
opens. :-(

--
John Fields

I think you are right. How about this one?

(Note, please view in mono-spaced font, like courier)

5V
----------o-------o--------o--o-----------------------o----+
| | | | .---------------. | |
.-. .-. | | | | | .-.
|R| |R| | | |--- GND Vcc ---+ |R|
|1| |2| - | | | | |3|
'-' '-' ^ | | | U1 | '-'
| | R4 | | | | | |
| || | ___ | | | | | |
----||--o--|___|-o--|-|--- Trg Dis --------o
| || | | | | |
| C1 | | | Thr --------o
| +-----------|-|--- Out | |
| | | | | | |
| | |----- Rst Ctl ---+ |
| | | | | | |
\ o | | | | | |
\ | | | | | ---
\. | | | | | ---
o | | '---------------' | | C2
| output | | |
| | --- |
| | --- |
Gnd | | C3 | |
---------o---------------------o---------------------o----+

R1=1k C1=1uF D1=1N4148
R2=10k C2=10uF
R3=91k C3=0.1uF U1=TN555CN
R4=100k

created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Regards,
Bob Monsen

 

[Terry Pinnell]

"Robert C Monsen" <rcsurname@comcast.net> wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:6ffle01kr2l54bosdi060g07p7hv7m145s@4ax.com...
On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
rcsurname@comcast.net> wrote:

Unfortunately, because of bounce it will also fire when the switch
opens. :-(

I think you are right. How about this one?
snip circuit with aded 100k at pin 2

I don't see how that will help?

I reckon this should be OK:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimer-Nikki.gif

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Robert C Monsen]

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...

"Robert C Monsen" <rcsurname@comcast.net> wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:6ffle01kr2l54bosdi060g07p7hv7m145s@4ax.com...
On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
rcsurname@comcast.net> wrote:

Unfortunately, because of bounce it will also fire when the
switch
opens. :-(


I think you are right. How about this one?
snip circuit with aded 100k at pin 2

I don't see how that will help?

What happens is that the switch bounces on open cause the node behind
the cap to wiggle above the rail... The diode behind the 100k resistor
(or protection diode inside the chip) keeps this from hurting the
chip's inputs. . On open bounces, the trigger pin never gets lower
than about 4.5V.

Give it a try, I built it, it works...

I reckon this should be OK:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimer-Nikki.gif

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Terry Pinnell]

"Robert C Monsen" <rcsurname@comcast.net> wrote:

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:6ffle01kr2l54bosdi060g07p7hv7m145s@4ax.com...
On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
rcsurname@comcast.net> wrote:

Unfortunately, because of bounce it will also fire when the
switch
opens. :-(


I think you are right. How about this one?
snip circuit with aded 100k at pin 2

I don't see how that will help?

What happens is that the switch bounces on open cause the node behind
the cap to wiggle above the rail... The diode behind the 100k resistor
(or protection diode inside the chip) keeps this from hurting the
chip's inputs. . On open bounces, the trigger pin never gets lower
than about 4.5V.

Give it a try, I built it, it works...

OK, then my 555 model must be unrealistic, or my
schematic/configuration flawed. I still got spurious triggering when I
simulated it:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM2.gif

(If you want, I'll send you the CKT and PWL.)

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Robert C Monsen]

----- Original Message -----
From: "Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com>
Newsgroups: sci.electronics.basics
Sent: Wednesday, July 07, 2004 10:14 PM
Subject: Re: Looking for a circuit to

"Robert C Monsen" <rcsurname@comcast.net> wrote:


"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in
message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:6ffle01kr2l54bosdi060g07p7hv7m145s@4ax.com...
On Mon, 05 Jul 2004 16:38:17 GMT, "Robert C Monsen"
rcsurname@comcast.net> wrote:

Unfortunately, because of bounce it will also fire when the
switch
opens. :-(


I think you are right. How about this one?
snip circuit with aded 100k at pin 2

I don't see how that will help?

What happens is that the switch bounces on open cause the node
behind
the cap to wiggle above the rail... The diode behind the 100k
resistor
(or protection diode inside the chip) keeps this from hurting the
chip's inputs. . On open bounces, the trigger pin never gets lower
than about 4.5V.

Give it a try, I built it, it works...

OK, then my 555 model must be unrealistic, or my
schematic/configuration flawed. I still got spurious triggering when
I
simulated it:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM2.gif

(If you want, I'll send you the CKT and PWL.)

--
Terry Pinnell
Hobbyist, West Sussex, UK

No, you put the diode to 5V on the wrong side of the 100k resistor.

The problem is that the diode keeps that node from getting up above
5.7V, so
the quick drops of the far left side on switch bounce cause the chip
to trigger.
Putting the diode on the other side of the 100k resistor means it
doesn't
affect that node as much, which can now go up to 10V when the switch
opens.
Thus, bounces on switch open now bounce between 10V and 5V rather than
5V
and 0V, and therefore don't trigger the 555. The diode simply protects
the
555 from any damage that the 10V might cause, and is probably not
required
for cmos 555s, since they have input protection diodes anyway.

Regards,
Bob Monsen

 

[Terry Pinnell]

"Robert C Monsen" <rcsurname@comcast.net> wrote:

OK, then my 555 model must be unrealistic, or my
schematic/configuration flawed. I still got spurious triggering when
I
simulated it:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM2.gif

(If you want, I'll send you the CKT and PWL.)

No, you put the diode to 5V on the wrong side of the 100k resistor.

The problem is that the diode keeps that node from getting up above
5.7V, so
the quick drops of the far left side on switch bounce cause the chip
to trigger.
Putting the diode on the other side of the 100k resistor means it
doesn't
affect that node as much, which can now go up to 10V when the switch
opens.
Thus, bounces on switch open now bounce between 10V and 5V rather than
5V
and 0V, and therefore don't trigger the 555. The diode simply protects
the
555 from any damage that the 10V might cause, and is probably not
required
for cmos 555s, since they have input protection diodes anyway.

Thanks for the fast reply. Still simulates a retrigger! Can you see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build it?


--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Robert C Monsen]

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:crqpe0hliemccj330t7ip1p9mctfuho8i5@4ax.com...

"Robert C Monsen" <rcsurname@comcast.net> wrote:


OK, then my 555 model must be unrealistic, or my
schematic/configuration flawed. I still got spurious triggering
when
I
simulated it:
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM2.gif

(If you want, I'll send you the CKT and PWL.)


No, you put the diode to 5V on the wrong side of the 100k resistor.

The problem is that the diode keeps that node from getting up above
5.7V, so
the quick drops of the far left side on switch bounce cause the
chip
to trigger.
Putting the diode on the other side of the 100k resistor means it
doesn't
affect that node as much, which can now go up to 10V when the
switch
opens.
Thus, bounces on switch open now bounce between 10V and 5V rather
than
5V
and 0V, and therefore don't trigger the 555. The diode simply
protects
the
555 from any damage that the 10V might cause, and is probably not
required
for cmos 555s, since they have input protection diodes anyway.

Thanks for the fast reply. Still simulates a retrigger! Can you see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build it?


--
Terry Pinnell
Hobbyist, West Sussex, UK

I simulated it and built it. However, the bounce.pwl file I used is
probably different from yours. I'm guessing thats the difference. Here
is mine. The assumption is that the bounce lasts 10ms.

+ 0 5
+ 1.001 5
+ 1.002 0
+ 1.003 5
+ 1.004 0
+ 1.005 5
+ 1.006 0
+ 1.007 5
+ 1.008 0
+ 1.009 5
+ 1.010 0
+ 1.011 0
+ 2 0
+ 2.001 5
+ 2.002 5
+ 2.003 0
+ 2.004 5
+ 2.005 0
+ 2.006 5
+ 2.007 0
+ 2.008 5
+ 2.009 5
+ 3 5

 

[Terry Pinnell]

"Robert C Monsen" <rcsurname@comcast.net> wrote:

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote
Thanks for the fast reply. Still simulates a retrigger! Can you see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build it?

I simulated it and built it. However, the bounce.pwl file I used is
probably different from yours. I'm guessing thats the difference. Here
is mine. The assumption is that the bounce lasts 10ms.

<snip PWL>

I've since discovered that if I use the alternative CM macromodel,
'555' instead of the component model 'UA555', your circuit simulates
OK (with my PWL as well as yours).

Where was that PWL applied in your simulation? As it's -ve going, I
assume it is direct to the LH side of your 1uF? Mine was +ve going,
and went via an intermediate VCVS. I suppose that was redundant, but I
assume it's immaterial here.

FWIW, here's my PWL. Similar order of bounce duration to yours, but
with bouncing on both open and close.

+ 0 0
+ 1m 0
+ 1.1m 5
+ 1.5m 5
+ 1.6m 0
+ 1.7m 5
+ 5m 5
+ 5.1m 0
+ 10m 0
+ 10.01m 5
+ 1.6s 5
+ 1.601 0
+ 1.61 0
+ 1.611 5
+ 1.62 5
+ 1.63 0

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Robert C Monsen]

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:arhse0p22iuthnu3h3rcoqk1c76setitdm@4ax.com...

"Robert C Monsen" <rcsurname@comcast.net> wrote:


"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote
Thanks for the fast reply. Still simulates a retrigger! Can you
see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build
it?

I simulated it and built it. However, the bounce.pwl file I used is
probably different from yours. I'm guessing thats the difference.
Here
is mine. The assumption is that the bounce lasts 10ms.

snip PWL

I've since discovered that if I use the alternative CM macromodel,
'555' instead of the component model 'UA555', your circuit simulates
OK (with my PWL as well as yours).

Where was that PWL applied in your simulation? As it's -ve going, I
assume it is direct to the LH side of your 1uF? Mine was +ve going,
and went via an intermediate VCVS. I suppose that was redundant, but
I
assume it's immaterial here.

FWIW, here's my PWL. Similar order of bounce duration to yours, but
with bouncing on both open and close.

+ 0 0
+ 1m 0
+ 1.1m 5
+ 1.5m 5
+ 1.6m 0
+ 1.7m 5
+ 5m 5
+ 5.1m 0
+ 10m 0
+ 10.01m 5
+ 1.6s 5
+ 1.601 0
+ 1.61 0
+ 1.611 5
+ 1.62 5
+ 1.63 0

--
Terry Pinnell
Hobbyist, West Sussex, UK

The PWL file I posted starts with an open switch, waits a second
before opening the switch, then waits another second before closing
the switch again. Both the closing and opening bounce for a bit. I
don't really know whether the bounce profile is accurate, but it seems
to work with both of the 555 models.

I've read that switch bouncing occurs over a period of 1ms, from 10 to
100 times. That is, the switch bounces 10 to 100 times, with a
frequency between 10kHz and 100kHz. My bounce.pwl file has it bouncing
with 500Hz frequency over a period of 10ms. Yours has it bouncing with
50Hz frequency a couple of times. I'm guessing thats the difference.
If you scope the trigger node using your PWL file, you see that the
trigger input gets down to 2V on the switch opening... I'm not sure
why the models differ in their response to this; the mono should
trigger in both cases.

Anyway, I believe the circuit works properly. If resiliency to longer
bounces is required, a larger time constant can be used by increasing
either the cap or 10k resistor. Increase the 100k resistor in
proportion to the increase in the 10k resistor. For example, changing
the 10k to a 22k, and the 100k to a 220k makes the circuit simulate
properly with your PWL file, at least for me.

Regards,
Bob Monsen

 

[Robert C Monsen]

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:arhse0p22iuthnu3h3rcoqk1c76setitdm@4ax.com...

"Robert C Monsen" <rcsurname@comcast.net> wrote:


"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote
Thanks for the fast reply. Still simulates a retrigger! Can you
see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build
it?

I simulated it and built it. However, the bounce.pwl file I used is
probably different from yours. I'm guessing thats the difference.
Here
is mine. The assumption is that the bounce lasts 10ms.

snip PWL

I've since discovered that if I use the alternative CM macromodel,
'555' instead of the component model 'UA555', your circuit simulates
OK (with my PWL as well as yours).

Where was that PWL applied in your simulation? As it's -ve going, I
assume it is direct to the LH side of your 1uF? Mine was +ve going,
and went via an intermediate VCVS. I suppose that was redundant, but
I
assume it's immaterial here.

FWIW, here's my PWL. Similar order of bounce duration to yours, but
with bouncing on both open and close.

+ 0 0
+ 1m 0
+ 1.1m 5
+ 1.5m 5
+ 1.6m 0
+ 1.7m 5
+ 5m 5
+ 5.1m 0
+ 10m 0
+ 10.01m 5
+ 1.6s 5
+ 1.601 0
+ 1.61 0
+ 1.611 5
+ 1.62 5
+ 1.63 0

--
Terry Pinnell
Hobbyist, West Sussex, UK

The PWL file I posted starts with an open switch, waits a second
before opening the switch, then waits another second before closing
the switch again. Both the closing and opening bounce for a bit. I
don't really know whether the bounce profile is accurate, but it seems
to work with both of the 555 models.

I've read that switch bouncing occurs over a period of 1ms, from 10 to
100 times. That is, the switch bounces 10 to 100 times, with a
frequency between 10kHz and 100kHz. My bounce.pwl file has it bouncing
with 500Hz frequency over a period of 10ms. Yours has it bouncing with
50Hz frequency a couple of times. I'm guessing thats the difference.
If you scope the trigger node using your PWL file, you see that the
trigger input gets down to 2V on the switch opening... I'm not sure
why the models differ in their response to this; the mono should
trigger in both cases.

Anyway, I believe the circuit works properly. If resiliency to longer
bounces is required, a larger time constant can be used by increasing
either the cap or 10k resistor. Increase the 100k resistor in
proportion to the increase in the 10k resistor. For example, changing
the 10k to a 22k, and the 100k to a 220k makes the circuit simulate
properly with your PWL file, at least for me.

Regards,
Bob Monsen

 

[Animesh Maurya]

Terry Pinnell <terrypinDELETE@THESEdial.pipex.com> wrote in message news:<arhse0p22iuthnu3h3rcoqk1c76setitdm@4ax.com>...

"Robert C Monsen" <rcsurname@comcast.net> wrote:

Hi Terry,

Although i am familiar with pspice, but had never simulated switch bounce behavior.
Which part it used to simulate that?

Thanks

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote
Thanks for the fast reply. Still simulates a retrigger! Can you see
any other error in this schematic?
http://www.terrypin.dial.pipex.com/Images/WindowSwTimerSIM3.gif

If not, has to be the model. Did you simulate as well as build it?

I simulated it and built it. However, the bounce.pwl file I used is
probably different from yours. I'm guessing thats the difference. Here
is mine. The assumption is that the bounce lasts 10ms.

snip PWL

I've since discovered that if I use the alternative CM macromodel,
'555' instead of the component model 'UA555', your circuit simulates
OK (with my PWL as well as yours).

Where was that PWL applied in your simulation? As it's -ve going, I
assume it is direct to the LH side of your 1uF? Mine was +ve going,
and went via an intermediate VCVS. I suppose that was redundant, but I
assume it's immaterial here.

FWIW, here's my PWL. Similar order of bounce duration to yours, but
with bouncing on both open and close.

+ 0 0
+ 1m 0
+ 1.1m 5
+ 1.5m 5
+ 1.6m 0
+ 1.7m 5
+ 5m 5
+ 5.1m 0
+ 10m 0
+ 10.01m 5
+ 1.6s 5
+ 1.601 0
+ 1.61 0
+ 1.611 5
+ 1.62 5
+ 1.63 0

 

[Animesh Maurya]

"Robert C Monsen" <rcsurname@comcast.net> wrote in message news:<F7%Gc.41791$XM6.18848@attbi_s53>...

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote:

Give it a try, I built it, it works...

Hi Bob,

I beardboarded your schematic and found that there was no false
trigger (not even for a single time) due to switch bounce.

Will you please point out where i'm going wrong?

Maybe it depends upon type of switch used!

Thanks

 

[Robert C Monsen]

"Animesh Maurya" <animesh_m@eudoramail.com> wrote in message
news:9f6c9f5d.0407120726.79606d17@posting.google.com...

"Robert C Monsen" <rcsurname@comcast.net> wrote in message
news:<F7%Gc.41791$XM6.18848@attbi_s53>...
"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in
message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote:

Give it a try, I built it, it works...

Hi Bob,

I beardboarded your schematic and found that there was no false
trigger (not even for a single time) due to switch bounce.

Will you please point out where i'm going wrong?

Maybe it depends upon type of switch used!

Thanks

Did you breadboard the 'corrected' circuit? If so, there should be no
false triggering.

The first circuit I posted had a problem with switch opening, as
pointed out by John Fields. If you hold the switch closed for 2
seconds, the LED (or whatever you are powering for 1 seconds) should
go out. Then, open the switch, and the 555 will be triggered again if
the switch bounces.

The second circuit is designed to prevent that by preventing the
bounce on switch opening from taking the trigger input down to 1.66V,
and thus never triggering the 555.

I believe that wwitch bounce is much more likely on switch closing
than opening, for obvious mechanical reasons. If your switch is not
bouncing on open, you may not have a problem with the first circuit.

Regards,
Bob Monsen

 

[Animesh Maurya]

"Robert C Monsen" <rcsurname@comcast.net> wrote in message news:<euBIc.62579$a24.1594@attbi_s03>...

"Animesh Maurya" <animesh_m@eudoramail.com> wrote in message
news:9f6c9f5d.0407120726.79606d17@posting.google.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote in message
news:<F7%Gc.41791$XM6.18848@attbi_s53>...
"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in
message
news:b7loe0hc57bqare5cqh1k9t394nqtv3tvg@4ax.com...
"Robert C Monsen" <rcsurname@comcast.net> wrote:

Did you breadboard the 'corrected' circuit? If so, there should be no
false triggering.

I referred your first circuit.

The first circuit I posted had a problem with switch opening, as
pointed out by John Fields. If you hold the switch closed for 2
seconds, the LED (or whatever you are powering for 1 seconds) should
go out. Then, open the switch, and the 555 will be triggered again if
the switch bounces.

This is what, that's not happening!

The second circuit is designed to prevent that by preventing the
bounce on switch opening from taking the trigger input down to 1.66V,
and thus never triggering the 555.

I believe that wwitch bounce is much more likely on switch closing
than opening, for obvious mechanical reasons. If your switch is not
bouncing on open, you may not have a problem with the first circuit.

Exactly this is the case.

Regards,
Bob Monsen

 

[Terry Pinnell]

animesh_m@eudoramail.com (Animesh Maurya) wrote:

Terry Pinnell <terrypinDELETE@THESEdial.pipex.com> wrote in message news:<arhse0p22iuthnu3h3rcoqk1c76setitdm@4ax.com>...
"Robert C Monsen" <rcsurname@comcast.net> wrote:

Hi Terry,

Although i am familiar with pspice, but had never simulated switch bounce behavior.
Which part it used to simulate that?

I use CircuitMaker, which is based on Berkeley Spice3f5/XSpice. To
simulate bounce, I specify 'Piece-Wise Linear' mode for my signal
generator, then write a PWL file in my text editor to specify the
signal I want to simulate, like the one I included earlier in the
thread. I think PSpice is similar in this context.

--
Terry Pinnell
Hobbyist, West Sussex, UK