Chip with simple program for Toy

[Mike Norton]

I set it at two amperes charge rate, low-maintenance (gel cell or AGM).
These are separate settings. In many cases, I suspect you are correct about
not needing to be charged; at least, it does not overcharge it like the
WallWart charger does.

One time, after using the starter on a recalcitrant .91 for what seemed like
an hour, it took 2 hours to charge it.

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:70Kve.3096$Bn6.997@trndny08...

Mike Norton wrote:
I bought a charger for 69 dollars from Sears. It charges anything that
is 12V lead acid under 200 AH, including small gel cells. You can
connect the battery up backwards with no harm to charger or battery. It
can also provide a 100A burst to help start an engine (car engine, that
is).

I have been charging 7AH gel cells with no problem after every use. It
normally takes less than a minute.

Something is very wrong.
A battery that charges in less than a minute either
did not need to be charged, was charged *WAY* too fast,
or wasn't really charged, due to the charger shutting
off when it shouldn't.

Check the instructions for your charger - is there something
different you need to do when charging gel cells vs car
batteries?

Ed

snip


-- Mike Norton

 

[ehsjr]

jjbutera@hotmail.com wrote:

My friend acquired a police lightbar from an old police cruiser, and we
thought it might be fun to use it with our band on stage. I haven't had
a chance to look at it closely yet to inspect the ratings and such, but
I'd like to be able to convert it so instead of running of a car's 12V
battery that it be plugged in to run on 120V AC. I believe this thing
probably draws 30 to 40 amps from the car battery.

Can anybody tell me how I would go about with this conversion? The
light bar has three stages (spots, intersection lights, main spinning
lights). I'm creating a stompbox that we can use to turn off/on each
stage. I know how to do this. I just don't know how to do the 12V DC
conversion to 120V AC.

I hope I'm correct in assuming that I can decrease the amperage
significantly by increasing the voltage (P=I*V) or else it becomes
unusable in an outlet served by a 15A breaker.

Any suggestions on how to do this conversion? It seems that it should
be pretty easy. I just don't know the steps involved.

Jason

First, find out how much current you really need. My bet is
that it needs *WAY* less than that.

Next, the easiest conversion is a DC power supply that provides
12 volts at the current you really need. A 30 to 40 amp supply
is not cheap, so it is mandatory that you find out how much
current you really need.

It also it is possible to use 12 volts AC with a transformer
to run bulbs in the unit. The bulbs will work fine on AC or
DC - but there may be motors and blinkers in the unit that
will work on DC only. A transformer should cost less than a
DC supply.

Converting by changing the parts in the unit to 120 vac parts
brings up safety issues, but it is probably a non-starter
anyway. It would mean gutting the unit down to an empty shell,
then installing 120 vac stuff in it to replace the 12 vdc stuff
you removed. The installation of the new bulb sockets would
likely be a mechanical nightmare.

Ed

 

[GregS]

In article <2dc6c1dp7f6ksctjulg4viuts31bi644kk@4ax.com>, John Fields <jfields@austininstruments.com> wrote:

On Wed, 29 Jun 2005 23:22:31 GMT, "olddog" <olddog@newtrox.com> wrote:

Er, i think the best way to charge a car battery, is to leave it in the car.

---
And drive around for a while.

That might not be safe!

greg

 

[John Fields]

On 30 Jun 2005 07:29:53 -0700, "Malcx" <mbailey@aethon.co.uk> wrote:

Can anyone help me with this seemingly simple circuit design? (I can
fit it all together, pcb design etc once I've the circuit diagram)

---
I can help you, but what are you planning on using for moisture
probes?

--
John Fields
Professional Circuit Designer

 

[Dan Hollands]

There are commercial water detection devices available to warn of water in
the basement

I don't know the brand but the plumber installed one when I had a back up
sump pump installed in the house where I used to live. I made a loud beeping
sound when it got wet. It ran off a battery

--

Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
QuickScore@USSailing.net
www.QuickScoreRace.com


"Malcx" <mbailey@aethon.co.uk> wrote in message
news:1120141793.122575.292310@o13g2000cwo.googlegroups.com...

Hi all,


I've not dabled with any electronics since High school (about 10 years)
and have a fairly specific requirement for a detector that I want/need
to put together....

Background:
My storage tank leaked and ruined the flooring - the plumber couldnt
find anything obviously wrong with the tank but replaced the pieces
that showed signs of wear and we've had no obvious leakage since...

Now before the floor is re-laid I want to be doublly sure there no slow
leak going on...

As the storage tank gets warm, any surface (i.e. detectable) water will
evaporate pretty quickly while other moisture will seep out of sight
and do damage...

Specification:
I envisgae all being contained in a small box with probes coming out on
lengthy wires.

The box will have an LED that is permenantly on when the battery has
power (I'd envisage a 9v cell...)

There would need to be 2 or 3 moisture detection probes, when any 1
probe registers moisture another led on the box will be lit. This led
remains lit even after the probe dries. Only 1 led will be needed for
all of the probes - i.e. there does not need to be an led for each
probe.

A reset button will be required to reset the state of the device back
to "power led on only" mode.

(Ideally the sensitivity of the probes would be adjustable)

Can anyone help me with this seemingly simple circuit design? (I can
fit it all together, pcb design etc once I've the circuit diagram)

Thanks for your help in advance!

Mal

 

[John Fields]

On 30 Jun 2005 09:29:38 -0700, "Malcx" <mbailey@aethon.co.uk> wrote:

Initially I was just thinking of just using etched copper board as we
used to in school - is there a better/more reliable alternative?

---
Depends. I you're looking for the difference between wet and dry,
that's probably as good a way to do it as any, but if you want to
detect 'damp' then something like, say, blotter paper sandwiched
between two wire grids would be better.

In either case, though, the circuitry will be the same, so the choice
of sensor is largely moot.

--
John Fields
Professional Circuit Designer

 

[Terry Pinnell]

"Malcx" <mbailey@aethon.co.uk> wrote:

Hi all,


I've not dabled with any electronics since High school (about 10 years)
and have a fairly specific requirement for a detector that I want/need
to put together....

Background:
My storage tank leaked and ruined the flooring - the plumber couldnt
find anything obviously wrong with the tank but replaced the pieces
that showed signs of wear and we've had no obvious leakage since...

Now before the floor is re-laid I want to be doublly sure there no slow
leak going on...

As the storage tank gets warm, any surface (i.e. detectable) water will
evaporate pretty quickly while other moisture will seep out of sight
and do damage...

Specification:
I envisgae all being contained in a small box with probes coming out on
lengthy wires.

The box will have an LED that is permenantly on when the battery has
power (I'd envisage a 9v cell...)

There would need to be 2 or 3 moisture detection probes, when any 1
probe registers moisture another led on the box will be lit. This led
remains lit even after the probe dries. Only 1 led will be needed for
all of the probes - i.e. there does not need to be an led for each
probe.

A reset button will be required to reset the state of the device back
to "power led on only" mode.

(Ideally the sensitivity of the probes would be adjustable)

Can anyone help me with this seemingly simple circuit design? (I can
fit it all together, pcb design etc once I've the circuit diagram)

Thanks for your help in advance!

Mal

I had a similar problem about 20 years ago. Some time later I wrote an
elementary article about the resultant project in an electronics
hobbyist magazine, which you might find useful. My output was a
miniature loudspeaker, not LEDS, but you may be able to adapt it.

http://www.terrypin.dial.pipex.com/Images/DampDetect.jpg
http://www.terrypin.dial.pipex.com/Images/DampDetect.txt
http://www.terrypin.dial.pipex.com/Images/DampDetector.gif
http://www.terrypin.dial.pipex.com/Images/DampFigs.gif

The magazine illustration scan is very poor, but the key schematic is
shown separately.

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Andrew Holme]

billcalley wrote:

I'm kind of stuck on making a 50 ohm power source in Spice (instead
of just using the voltage or current sources). I would like to make a
50 ohm power source with a Pout of 0dBm. I realize I have to use the
Spice voltage source with a series 50 ohm resistor, but do I set the
voltage source to 632 mV or 316 mV in order to get a 0dBm Pout (in a
fifty ohm system)?

Thank You,

Bill

The voltage across the load will be half the generator voltage.
Don't get confused between peak and rms.

Power = Vrms*Vrms/R = Vpk*Vpk / 2R

Generator voltage = 632mV (peak)
Load voltage = 316mV (peak)
Load power = 0.316 * 0.316 / 2 / 50 ~ 1mW

 

[Rheilly Phoull]

One day Malcx got dressed and committed to text

Hi all,


I've not dabled with any electronics since High school (about 10
years) and have a fairly specific requirement for a detector that I
want/need to put together....

Background:
My storage tank leaked and ruined the flooring - the plumber couldnt
find anything obviously wrong with the tank but replaced the pieces
that showed signs of wear and we've had no obvious leakage since...

Now before the floor is re-laid I want to be doublly sure there no
slow leak going on...

As the storage tank gets warm, any surface (i.e. detectable) water
will evaporate pretty quickly while other moisture will seep out of
sight and do damage...

Specification:
I envisgae all being contained in a small box with probes coming out
on lengthy wires.

The box will have an LED that is permenantly on when the battery has
power (I'd envisage a 9v cell...)

There would need to be 2 or 3 moisture detection probes, when any 1
probe registers moisture another led on the box will be lit. This led
remains lit even after the probe dries. Only 1 led will be needed for
all of the probes - i.e. there does not need to be an led for each
probe.

A reset button will be required to reset the state of the device back
to "power led on only" mode.

(Ideally the sensitivity of the probes would be adjustable)

Can anyone help me with this seemingly simple circuit design? (I can
fit it all together, pcb design etc once I've the circuit diagram)

Thanks for your help in advance!

Mal

Not an electronic solution but in our part of the world concealed storage
tanks are usually installed in a 'tray' fitted with a drain to waste which
would take care of the floor spoiling effect.

--
Regards ..... Rheilly Phoull

 

[John Fields]

On 1 Jul 2005 01:23:31 -0700, "Malcx" <mbailey@aethon.co.uk> wrote:

Yeah Just wet vs dry is enough for me - mearly knowing that water has
been present since I last checked is enough to tell me there is a
problem that I'll need to call the plumber back for.

As water's not pouring out I'm in favor of an LED warninfg rather than
buzzer as being woken at 2 in the morning wouldnt be appreciated by the
girlfriend ;-)

Having said all that I'm looking at this as a learning excercise as
well and like the thought of damp detection with wire grids/blotter
paper - would it be a massive undertaking to do an LED scale (say 1-5)
measuring how damp it had been?

---
No, but the probe will be tricky.
---

(i.e. if it is just damp 1 LED lights, under water = all 5 light with
the display "locking" at the highest level recorded since last reset? -
this is beyond what I need to do but if still fairly straightforward
would be more fun!)

---
The circuitry's pretty straightforward but, again, the probe will be
tricky, so, first things first and I'll generate something for you for
the wet/dry unit.

BTW, how long do the cables have to be and what kind of a power supply
do you want to use to run the thing?
---

--
John Fields
Professional Circuit Designer

 

[Larry Brasfield]

"Will" <a7b98208@telus.net> wrote in message
news:Mrfxe.102417$9A2.54958@edtnps89...

Hi All,
Hi.
I am interfacing a ham radio to a computer to program it and I have been
looking at various TTL / RS-232 conversion circuits. However I happen to
have a commercial ADMS programming cable I use with my Yaesu VX-7R radio
(ham radio). This cable also handles this type of conversion so I am
thinking why reinvent the wheel when I can utilize this existing circuit
which is already integrated into the D-sub shell of this cable.

Thus my question:

These generic circuits appear to RS-232 logic levels (+/-12VDC) on pins 2 &
3 of a DB9 connector and converts them to 0 & 5VDC. Which TTL voltage
corresponds to a logic 0 and which to a logic 1?

Conventions differ on this between different signals
in the RS-232 standard. The modem control and
status signals are normally active low in the TTL realm.
If you want to deem that "TTL high = logic 0", that is
up to you. The data signals are normally considered
to be at the mark level for a high level in the TTL realm.
That is level usually considered a '1' when considered
to be a number at all.

On the RS-232 side, the
data pins use negative logic, so +3 to +12 VDC is logic 0 and -3 to -12VDC
is logic 1. Does the TTL data input use positive logic instead ( logic 1 is
+5VDC and logic 0 is 0VDC)?

All TTL<-->RS-232 translators that I have seen are
inverting, and they are used for both the data and the
status/control signals with every serial interface device
I have seen. Without having looked at your equipment,
I can say that if your translators invert, they are quite
likely to be doing the right thing.

What is the industry convention when terminating the TTL side of this cable
to a stereo plug. ... is the tip conductor logic 1 or logic 0?

I've not seen stereo plugs used for RS-232. But it makes
no sense to call the tip logic 1 or logic 0. Why would such
a limited number of conductors be wasted conveying a
constant value?

Once I
determine this, then I will use this existing conversion cable and simply
wire the stereo plug conductors to their respective TXD and RXD pins on my
Yaesu FT-857.

Go for it, I say.

Lastly, what happens if one connects the TTL level TX conductor to the TXD
pin on the radio side accidentally instead of the RXD pin on the radio?
i.e. wires crossed in error

No permanent harm, just some frustration and maybe
mystefication when it does not work as you want.

Thanks for any and all info!

You're welcome.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[John]

On 30 Jun 2005 07:29:53 -0700, "Malcx" <mbailey@aethon.co.uk> wrote:

Hi all,


I've not dabled with any electronics since High school (about 10 years)
and have a fairly specific requirement for a detector that I want/need
to put together....

Background:
My storage tank leaked and ruined the flooring - the plumber couldnt
find anything obviously wrong with the tank but replaced the pieces
that showed signs of wear and we've had no obvious leakage since...

Now before the floor is re-laid I want to be doublly sure there no slow
leak going on...

As the storage tank gets warm, any surface (i.e. detectable) water will
evaporate pretty quickly while other moisture will seep out of sight
and do damage...

Specification:
I envisgae all being contained in a small box with probes coming out on
lengthy wires.

The box will have an LED that is permenantly on when the battery has
power (I'd envisage a 9v cell...)

Not a good idea, since the LED will run down the 9v battery very
quickly. You probably want an AC powered device, possibly with
battery backup.

Some CMOS logic chips or a low power version of the 555 timer chip can
be used for the latch circuit that stays on after being tripped.

The most basic wet/dry sensor is a piece of circuit board with the
copper foil divided in two parts. Board size is dependent on the
expected size of the wet/damp area (or the drip area, as appropriate).

There would need to be 2 or 3 moisture detection probes, when any 1
probe registers moisture another led on the box will be lit. This led
remains lit even after the probe dries. Only 1 led will be needed for
all of the probes - i.e. there does not need to be an led for each
probe.

A reset button will be required to reset the state of the device back
to "power led on only" mode.

(Ideally the sensitivity of the probes would be adjustable)

Can anyone help me with this seemingly simple circuit design? (I can
fit it all together, pcb design etc once I've the circuit diagram)

Thanks for your help in advance!

Mal

 

[Don Klipstein]

In <1120255366.886634.79190@f14g2000cwb.googlegroups.com>, js5895 wrote:

Hi,

can I put a 60W fluorescent bulb, 120V 60Hz 14W 0.200A rated, in a 40W
rated socket.

This sounds like a 14 watt compact fluorescent that is supposed to
produce as much light as a 60 watt incandescent. I am guessing that this
compact fluorescent is a spiral one.

My experience tells me that the answer is generally probably yes, it
will not overheat a fixture rated for a 40 watt incandescent.

WARRANTY: If things go wrong, I will refund what you paid me for this
advice, and that's all that I will guarantee.

As for what could go wrong:

1. If the fixture is intended for tubular incandescents, you may have a
bit of a heat problem. 40 watt 120V tubular incandescents such as
"refrigerator bulbs" have a vacuum and have little heat
conducted/convected from them. Compact fluorescents, on the other hand,
produce little infrared and have nearly all output other than visible
light in the form of conducted/convected heat.
I don't have any data handy for a 14 watt compact fluorescent, but I did
have an 8 inch globe over a socket heat up more (29 degrees C) from a 20
watt spiral compact fluorescent than from a 40 watt tubular "T10"
incandescent (19.5 degrees C). I extrapolate that a 14 watt compact
fluorescent would have caused a temperature rise 70% of that of the 20
watt compact fluorescent, or about 20 degrees C, or very slightly more
temperature rise than with a 40 watt vacuum-containing incandescent.
Probably a non-problem, but no iron-clad guarantee.

However, a 20 watt spiral compact fluorescent heated up this globe less
than a 40 watt "A19" gas-filled incandescent did (37 degree C rise).

2. In recessed ceiling fixtures, other fixtures with openings only at
the bottom, and small enclosed fixtures, heat builds up. Compact
fluorescents are more vulnerable to this than incandescents are.
In my experience, this is usually not a problem with compact
fluorescents 13 watts or less. As for higher wattages - I have noticed 15
and 20 watt (and not higher wattages) of Philips SLS being rated for use
in recessed ceiling fixtures. A majority of the time I see other screw-in
models up to about 18 watts or so in such fixtures they appear to usually
get away with this, although I have seen spiral models apparently of a
wattage in the 19-24 watt range crack in ceiling fan fixtures.
Most recessed ceiling fixtures that I see in commercial buildings with
compact fluorescent lamps have ones other than screw-in models, and the
ballasts are not in the lamp/"bulb" but somewhere in the fixture,
presumably somewhat removed from the heat. I have seen many fixtures like
that with two 13-watt or two 26-watt lamps/"bulbs".

As for lack of problems using a 14 watt spiral compact fluorescent in a
recessed ceiling fixture, other downlight, or small enclosed fixture rated
for 40 watt incandescents: I believe you should get away with this, but I
give no guarantee.

- Don Klipstein (don@misty.com)

 

[Andrew Holme]

amremote@hotmail.com wrote:

I should know how to do this, but please treat as a Newbie query

I have a simple circuit question for any analogue experts out there !
I'd be delighted if someone can suggest what I suspect is a simple
solution. I have no problem with digital circuitry, or making the
solution. My problem is a lack of understanding of analogue bits n
pieces and lack of time to learn due to work pressures


THE PROBLEM

- I have to link a very modern fuel-tank level probe to an old
fashioned car fuel gauge, via a simple circuit and it all runs of the
cars 12v supply.


THE DETAILS

- The supply rail will be typically 12-14vs
- The fuel probe is an expensive dedicated hyper modern capacitive
device with a pic chip type device in it. Once calibrated it generates
a high impedance output voltage of 0-5v linearly. Linearity isn't
important to me. It cant source more than a milliamp.
- The old fuel gauge is a fixed resistance 45ohm device with internal
mechanical damping. It isn't very linear but this isn't important.
The gauge reads empty to full with a voltage change across it of 0 -
10volts, and current consumption of 0-230ma or so.
- The 0 -> 5v input signal is pretty much a steady DC value so I cant
have a capacitor on the input as in a conventional simple amplifier
circuit.


THE QUESTION

- What simple FET based (or transistor!) circuit would link these two
devices ? Ideally I'd like someone to advise on a schematic, with
approx component values, that I can go off and build and tweak.


Help !! If you want to email me offlist use amremote at hotmail dot
com

Thanks in advance.
Andy / UK.

You want a DC amplifier with a voltage gain of 2, high input impedance, and
high output current drive. You could use an op-amp non-inverting amplifier
with an emitter-follower buffering the output e.g. (view in fixed font)

' +12V
' Vin |\ |
' ---------------|+\ |/
' | >---------| Q1
' .-|-/ |>
' | |/ |
' | |
' | |
' R1 | R2 |
' ___ | ___ | Vout
' .---|___|----o------|___|-----o--------------
' '
' ===
' GND
'

You need an op-amp that runs off a single supply, with inputs that work down
to the negative supply rail.

Q1 will dissipate up to 1 Watt.

The two resistors (R1, R2) set the gain. R1=R2 for a gain of 2. I suggest
R1=R2=10k

I would include a 10uF power supply decoupling capacitor, and a 0.5A fuse in
the power lead.

I would also connect a large resistor (100k - 1M) from the input to ground,
in case it's left floating.

 

[Rich Webb]

On 1 Jul 2005 23:33:11 -0700, "ankur" <ankur.pathela@gmail.com> wrote:

Hi everyone,
I am trying to use CCM1620CSL(a 44780-based LCD module) and that is
the first LCD i am trying my hands on.
I have interfaced the LCD to a PIC and till now, whatever program I
run, the result is 16 black boxes on the 2nd line of LCD (it's a 16x2
LCD). Can anyone suggest why is it happening? Isn't the LCD
auto-initialized in the 8-bit, 1-line mode when no initialization
routine is found ?

The initialization requirements for the 44780-style modules are strict.
What you describe is characteristic of what happens without proper
initialization.

You're correct in that the module wakes up in 8-bit mode. However, even
in 8-bit mode there are a few time-critical steps that need to occur to
wake it up properly.

A good reference is http://www.optrex.com/pdf/Dmcman_full.pdf. Note that
this is for a particular manufacturer and, while the values will work
with most 44780-compatible modules, there may be some with slightly
different timing requirements with "clones." Consult the specific data
sheet, if available.

I've few more questions:
1) Can initialization be done only at the time of applying power to
the LCD? Suppose I wish to change the entry mode in the middle of my
program, how is it done?

Initialization is just that. However, there are commands to clear, to
change the operating mode, and to manipulate the display.

Datasheets are your friends.

2) Ideally, what do you expect to see on the LCD screen if ONLY power
is applied(i.e only Vdd,Vss & Vo are connected and rest of the pins are
left open)

One black bar. IIRC, the black bar is on line ONE and not line TWO. Any
chance that you have the display (and interface pin numbering) reversed?

--
Rich Webb Norfolk, VA

 

[Michael A. Terrell]

kell wrote:

- The supply rail will be typically 12-14vs
- The fuel probe is an expensive dedicated hyper modern capacitive
device with a pic chip type device in it. Once calibrated it generates
a high impedance output voltage of 0-5v linearly. Linearity isn't
important to me. It cant source more than a milliamp.
- The old fuel gauge is a fixed resistance 45ohm device with internal
mechanical damping. It isn't very linear but this isn't important.
The gauge reads empty to full with a voltage change across it of 0 -
10volts, and current consumption of 0-230ma or so.

I forgot to mention: in my post with the ASCII schematic, use a
proportional font to view it. If you are in Google, click options and
"view original."

You mean a non-proportional font.

If you use a proportional font, you have to know which one was used to
create the drawing so you can get things to line back up.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

 

[Rich Webb]

On 2 Jul 2005 09:28:41 -0700, "ankur" <ankur.pathela@gmail.com> wrote:

Hello Webb,
Thank you for the elaborate suggestions. The data sheet I currently
have, is least informative and I couldn't find any other datasheet of
the same manufacturer on the web.

I will work more on getting the initialization right. Can you tellme
what is observed on the screen when it gets initialized
successfully?(incase it is not different for different modules)

Initialization is just to a blank screen with or without a cursor (a
determined by the initialization).

One thing you'll need to decide on is whether you write to the display
with a fixed delay after each character (and a longer display after each
"clear screen") or whether you read back the "busy bit" from the display
controller.

--
Rich Webb Norfolk, VA

 

[John Popelish]

amremote@hotmail.com wrote:
(snip)

THE PROBLEM

- I have to link a very modern fuel-tank level probe to an old
fashioned car fuel gauge, via a simple circuit and it all runs of the
cars 12v supply.


THE DETAILS

- The supply rail will be typically 12-14vs
- The fuel probe is an expensive dedicated hyper modern capacitive
device with a pic chip type device in it. Once calibrated it generates
a high impedance output voltage of 0-5v linearly. Linearity isn't
important to me. It cant source more than a milliamp.

Just to be sure: Does 0V indicate empty or full?

- The old fuel gauge is a fixed resistance 45ohm device with internal
mechanical damping. It isn't very linear but this isn't important.
The gauge reads empty to full with a voltage change across it of 0 -
10volts, and current consumption of 0-230ma or so.
(snip)

Again, does 0 volts indicate empty or full?

No sense suggesting something that has a 50 50 chance of reading
backwards.

 

[John Popelish]

mowhoong@hotmail.com wrote:

I notice some fuse maker given voltage rating beside current rating
like 1 amp 250 volt & 1 amp 1000 volt, it make no diffrent on the
voltage as long any current reach more than 1 amp fuse will burn.
My explaination is correct ?

The current rating tells how much current can be passed without

melting. The voltage rating tells how much voltage can be interrupted
once the melt takes place.

 

[Will]

Hi Larry / the group,

Thank you for the reply.

I've done some more experimenting with my commerical grade cable used with
the Alinco DJ-X10 wideband radio.

I've run a number of tests to using a standard 9-pin RS-232 cable (no
conversion) and measured/monitored the TXD and RXD lines on a dual channel
scope to serve as a reference.

As expected, RS-232 data lines idled in a marking state of -11V. Then using
a Windows Hyperterminal session @ 4800 bps, 8 data bits, 1 stop bit, set my
time base on my scope to reflect 208 us/DIV sweep so each bit duration
consume one graticule division. I then monitored the voltages on this line
as I held down and pressed various keys while observing their binary
equivalent on an ASCII chart. I observed 10 bits as expected (1 start bit,
8 data bits, 1 stop bit) and the levels behaved as I would expect.

I captured the screen shots of my scope for each of the characters I used.
I then hooked up my RS-232 / TTL conversion cable for the Alinco unit (not
actually connected to the radio ... hence "unloaded") and observed the
following:

1. No logical start or stop bits are observed.
2. On some keys, the binary codes produced predictable results, i.e. the
letter U which has alternate bits set (01010101). The TTL output was
comparable, but at ~ 3.5V.
3. TTL levels ranged from 0 to 3.5V unlike RS-232 levels (+/-11V)
4. Not all voltage sequences while monitoring the TXD TTL-level conductor
matched its corresponding bit sequence observed when using the RS-232 (non
conversion) cable.
5. As I recall the RS-232 standard (many years ago for me), the whole
concept of serial communicaitons was asynchronous in nature and hence each
byte was enveloped by a start and stop bit(s) to sync the tx'er and the
rx'er. However, on the TTL side, it appears as though there is no concept
of start and stop bits ( at least logically). Yes, I understand that
there's either 0 or 5V. That's it. But there is no asynchronous start/stop
bits utilized on the TTL side.
6. Since the TTL-side voltage transitions did not always correspond to the
RS-232 equivalent (ie voltage transition intervals), I am wondering if some
sort of encoding scheme is used (NRZ, NRZI, etc) ???

What should data in the RS-232 realm on pin 3 look like after being
converted into TTL level voltages? In some cases, the RS-232 logic level 1
(-11V) seemed to correspond to 0V in the TTL realm. In other cases, it
seemed to correspond to 5V. ?

-W

PS: As for the stero plug, the tip did correspond to RS-232 RXD and the
ring conductor did correspond to RS-232 TXD. Since RS-232 is full duplex
(TXD/GND and RXD/GND pairs), I guess it stands to reason that this
conversion circuit still maintains two separate and distinct paths for
sending and receiving data.

PPS: Not sure I follow about the constant voltage level waiting a conductor.
Since the TTL signals seem to correspond in some relation to the originating
RS-232 data byte, the TTL level signal was only constant in voltage for the
duration of a bit, but it changed in magnitude (0 or 5V) accordingly.


"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:UCgxe.44$md4.6644@news.uswest.net...

"Will" <a7b98208@telus.net> wrote in message
news:Mrfxe.102417$9A2.54958@edtnps89...
Hi All,
Hi.
I am interfacing a ham radio to a computer to program it and I have been
looking at various TTL / RS-232 conversion circuits. However I happen
to
have a commercial ADMS programming cable I use with my Yaesu VX-7R radio
(ham radio). This cable also handles this type of conversion so I am
thinking why reinvent the wheel when I can utilize this existing circuit
which is already integrated into the D-sub shell of this cable.

Thus my question:

These generic circuits appear to RS-232 logic levels (+/-12VDC) on pins
2 &
3 of a DB9 connector and converts them to 0 & 5VDC. Which TTL voltage
corresponds to a logic 0 and which to a logic 1?

Conventions differ on this between different signals
in the RS-232 standard. The modem control and
status signals are normally active low in the TTL realm.
If you want to deem that "TTL high = logic 0", that is
up to you. The data signals are normally considered
to be at the mark level for a high level in the TTL realm.
That is level usually considered a '1' when considered
to be a number at all.

On the RS-232 side, the
data pins use negative logic, so +3 to +12 VDC is logic 0 and -3
to -12VDC
is logic 1. Does the TTL data input use positive logic instead ( logic
1 is
+5VDC and logic 0 is 0VDC)?

All TTL<-->RS-232 translators that I have seen are
inverting, and they are used for both the data and the
status/control signals with every serial interface device
I have seen. Without having looked at your equipment,
I can say that if your translators invert, they are quite
likely to be doing the right thing.

What is the industry convention when terminating the TTL side of this
cable
to a stereo plug. ... is the tip conductor logic 1 or logic 0?

I've not seen stereo plugs used for RS-232. But it makes
no sense to call the tip logic 1 or logic 0. Why would such
a limited number of conductors be wasted conveying a
constant value?

Once I
determine this, then I will use this existing conversion cable and
simply
wire the stereo plug conductors to their respective TXD and RXD pins on
my
Yaesu FT-857.

Go for it, I say.

Lastly, what happens if one connects the TTL level TX conductor to the
TXD
pin on the radio side accidentally instead of the RXD pin on the radio?
i.e. wires crossed in error

No permanent harm, just some frustration and maybe
mystefication when it does not work as you want.

Thanks for any and all info!

You're welcome.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.