Photoflash firing circuit

  • Thread starter Gordon Campbell
  • Start date
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Gordon Campbell

Guest
Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced in
a set pattern. ;-)
 
Subject: Photoflash firing circuit
From: "Gordon Campbell" gordon_no_spam@cruachan.ca
Date: 3/3/2004 8:27 PM Central Standard Time
Message-id: <%tw1c.16724$qA2.902464@news20.bellglobal.com

Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced in
a set pattern. ;-)
Click to expand...
A few questions. How many photoflash units do you have? Are they voltage
triggering or switch contact triggering? What is the recharge time for the
photoflash units?

Assuming you have contact triggering, it might be easiest to just go with 1 ea.
555 trigger circuit for each strobe. Each 555 would drive a small reed relay,
which would provide the trigger for each strobe. You could run the whole
shebang of triggers off one 6V lantern battery, and if you had more than 5
strobes, it would look semi-random.

However, I'm guessing your photoflash takes a couple of seconds to recharge, in
which case your photoflashes will look like a bunch of cameras going off rather
than an arcs & sparks event.

One thing you might want to consider, if you've got a bit of a budget and are
handy with a soldering iron, is getting half a dozen DIY K163 strobe kits (use
the 0.1 uF cap rather than the 0.47 uF cap for .2 to .4 second cycle), and a
12VDC power supply, like the ones available at Radio Shack (13.8VDC is OK
here). The kits are about $15.50 ea. Set all the pots for different times.
It will give you the randomness you seek, and probably would look more
realistic than your photoflash (although the photoflash would probably be
somewhat brighter -- a reflective backing and good sound effects would help
here). Just turn on the 12VDC to turn your show on, and turn off the power
supply to turn it off.

You might be somewhat disappointed with either solution, because a flash
doesn't have the high UV content of an arc. It will, alas, have the color of a
flashbulb, no matter what. A light purple wash filter on one of the strobes,
and light blue wash filter on one more may help here. Stay far away from the
temptation to use an arc welder here to get your spark light -- safety always
first backstage.

Good luck, and break a leg
Chris
 
On Wed, 3 Mar 2004 21:27:11 -0500, "Gordon Campbell"
<gordon_no_spam@cruachan.ca> wrote:

Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced in
a set pattern. ;-)


Sounds like all you need is a random number generator.
Click to expand...
While there are circuits to do this, you might have better
luck with a computer. That gives you the ability to
change things around, including changing them on
the fly during the performance.

There are plenty of random number algorithms out there.
Just set one up to output 8 bits to the printer port, and
you can drive 8 different stobes. Or you can have
several single-bit generators running at different rates.

If you want to test this out, you can download my
Daqarta software with the LPTX driver. There
is simple a random generator built into the driver, and
you can also use the STIM3A signal generator
to generate much more complex patterns.

Let me know if you need more info on this. You will
need a computer that runs real-mode DOS, which
means an old one, Win9x or earlier. Good use
for an old junker, even an 8088 PC/XT.





Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
We're look at 6 or 8 of the flash units and they'll be inside a prop light
board that is supposed to have had an axe buried into it. :)

The budget's more or less nil. We're using flashes that I've stripped out of
disposable cameras. I'll see what I can come up with. Thanks!


"CFoley1064" <cfoley1064@aol.com> wrote in message
news:20040304002642.09952.00000826@mb-m17.aol.com...
Subject: Photoflash firing circuit
From: "Gordon Campbell" gordon_no_spam@cruachan.ca
Date: 3/3/2004 8:27 PM Central Standard Time
Message-id: <%tw1c.16724$qA2.902464@news20.bellglobal.com

Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers
circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced
in
a set pattern. ;-)

A few questions. How many photoflash units do you have? Are they voltage
triggering or switch contact triggering? What is the recharge time for
the
photoflash units?

Assuming you have contact triggering, it might be easiest to just go with
1 ea.
555 trigger circuit for each strobe. Each 555 would drive a small reed
relay,
which would provide the trigger for each strobe. You could run the whole
shebang of triggers off one 6V lantern battery, and if you had more than 5
strobes, it would look semi-random.

However, I'm guessing your photoflash takes a couple of seconds to
recharge, in
which case your photoflashes will look like a bunch of cameras going off
rather
than an arcs & sparks event.

One thing you might want to consider, if you've got a bit of a budget and
are
handy with a soldering iron, is getting half a dozen DIY K163 strobe kits
(use
the 0.1 uF cap rather than the 0.47 uF cap for .2 to .4 second cycle), and
a
12VDC power supply, like the ones available at Radio Shack (13.8VDC is OK
here). The kits are about $15.50 ea. Set all the pots for different
times.
It will give you the randomness you seek, and probably would look more
realistic than your photoflash (although the photoflash would probably be
somewhat brighter -- a reflective backing and good sound effects would
help
here). Just turn on the 12VDC to turn your show on, and turn off the
power
supply to turn it off.

You might be somewhat disappointed with either solution, because a flash
doesn't have the high UV content of an arc. It will, alas, have the color
of a
flashbulb, no matter what. A light purple wash filter on one of the
strobes,
and light blue wash filter on one more may help here. Stay far away from
the
temptation to use an arc welder here to get your spark light -- safety
always
first backstage.

Good luck, and break a leg
Chris
Click to expand...
 
Holy cow, I never thought of that Bob. Boy, have I got computers ... Thanks!

"Bob Masta" <NoSpam@daqarta.com> wrote in message
news:40473705.3714377@news.itd.umich.edu...
On Wed, 3 Mar 2004 21:27:11 -0500, "Gordon Campbell"
gordon_no_spam@cruachan.ca> wrote:

Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers
circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced
in
a set pattern. ;-)


Sounds like all you need is a random number generator.
While there are circuits to do this, you might have better
luck with a computer. That gives you the ability to
change things around, including changing them on
the fly during the performance.

There are plenty of random number algorithms out there.
Just set one up to output 8 bits to the printer port, and
you can drive 8 different stobes. Or you can have
several single-bit generators running at different rates.

If you want to test this out, you can download my
Daqarta software with the LPTX driver. There
is simple a random generator built into the driver, and
you can also use the STIM3A signal generator
to generate much more complex patterns.

Let me know if you need more info on this. You will
need a computer that runs real-mode DOS, which
means an old one, Win9x or earlier. Good use
for an old junker, even an 8088 PC/XT.





Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Click to expand...
 
On Thu, 4 Mar 2004 13:52:43 -0500, "Gordon Campbell"
<gordon_no_spam@cruachan.ca> wrote:

Holy cow, I never thought of that Bob. Boy, have I got computers ... Thanks!
Click to expand...
Last night I just recalled an easier way to use Daqarta for this.
I left an undocumented feature in the DEMO.ADC driver, so
you don't even need to mess with LPTX. Just open the
default DQA.CFG file and to the second line add L:1
DEMO.ADC L:1
That will allow you to send STIM3A signals out the
printer port. (L:1 means use LPT1; you can select
LPT2 with L:2, etc.)

You control which STIM3A output (DAC0, DAC1, or
various DigOut bits) will be viewed as the DEMO input
signal, by changing the input channel on the DEMO
driver (B-key to toggle the Board active, CTRL-B to
Control the Board). See Help (CTRL-H) for a list of
what channel maps to what STIM3A output.

CTRL-G to bring up the generator. Depending on
what DEMO channel you set, the 8 bits of the printer
port output will be the 8 bits of a DAC, or 8 separatrely
controllable DigOut bits. Select a noise type for the
DAC and you will have 8 independent random
outputs. You can slow these down via the CTRL-X
X-axis sample rate controls, but a better way is to
use the Timing menu Step option. That will allow
you to hold each random value for as many samples
as you want.

Or, use the DigOut option and set different pulse
timing cycles on each of the 8 bits. You can make this
exceedingly complex, so that it will appear quite
random, yet still have some control over rates of
individual strobes.

Enjoy!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
"Gordon Campbell" <gordon_no_spam@cruachan.ca> wrote in message
news:%tw1c.16724$qA2.902464@news20.bellglobal.com...
Evening, all. I apologize if this is the wrong group to make this sort of
request, but I've run out of ideas.

I'm looking for a schematic of a circuit that will randomly fire a
collection of photo flash units.

I'm working tech for a play next month and we're looking to simulate
electronic arcing with the flash units. I can find dozens of timers
circuits
to fire the flashes, but every last one uses a set time. I need random or
something approaching that. I've never seen electrical shorts that arced
in
a set pattern. ;-)
Click to expand...

Why not fire them manually with a peg board? Or with a charge discharge
circuit manually controlled?
 
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