Strobe Light Triggers?

[macumbista]

Has anyone worked with strobe lights which take a 5V trigger? I'd like to know if the trigger should be of a fixed length of time. Does the strobe have a fixed time that it is on, or does it remain on for the length of the trigger? Basically, I'd like to know if building a comparator with a 5V output would be enough to be able to control the strobe from my synth, or if I need to make that pulse output a narrow trigger.

[PickNick]

hi!
i think the trigger generator network circuit it would be works.
http://ericarcher.net/devices/tr808-clone/
just a few components:)

[PHOBoS]

The strobe lights I've used only give one flash on a high input (you do mean the flashing things right?). But when you trigger it, it discharges a small cap to get the high voltage, and this cap only gets charged again when the input is low,. so for fast rates a short pulse would be best.

I usually use a NE555 circuit for it,..

[macumbista]

In the end, I used a simple op-amp comparator circuit, with an LFO as input. That way the strobe triggers in relation to the sounds I'm playing from the synth. If the LFO goes too fast, I don't get triggers anymore, but besides that it's fine.

At first I thought I'd be able to control the brightness with the voltage level of the pulse. Wouldn't it be cool if that actually worked??? No need for expensive DMX stuff. Of course it's not that simple...

I didn't bother messing with the level of the trigger in the end, I'm probably sending something close to a 15V trig to the strobe but it doesn't seem to mind.

What would be cool would be something to shorten the length of the trigger. Then I could probably get the rate of the strobe a bit higher before it conks out. I tried the CGS gate to trigger converter but it didn't seem to do the trick. Ah well... I'm checking out Arduino DMX stuff next anyways.

[PHOBoS]

Nice to hear it's working, it's always fun to add some lights to your music.
To shorten the pulse you could try the following circuit, which is what i use to trigger my strobes.

I usually put it in the strobelight itself, so I use an optocoupler for safety reasons and it also prevents any noise from travelling back over the control line. In your case, with 15 Volts, 1.2Kohm would be a good value for R. The IN4148 diode is to protect the optocoupler but it's not necessary. You could replace the optocoupler with a NPN transistor and trigger that or leave all the parts marked in red out and just add your signal (from the comparator) to the 1nF cap, but then it will work inverted so a low pulse would trigger the strobe. The pulse length might not even be the problem, there is a max pulserate of course which has to do with charging and discharging the cap(s) that supply the power for the flash. But you could give it a try,..

[macumbista]

That's totally awesome, thanks! Yes, it would be smart to use an optocoupler, I was just in a hurry with a gig last weekend already lined up with the strobe.

What is the level of the pulse out? Does it equal VDD?

It has to be something external to the strobe because I have no intention of trying to check four strobe lights in my luggage when I travel to performances!!!!

I asked around on some of these "professional" lighting forums, and got the old "you're a DIY guy, you can figure it out yourself" line. They wouldn't even dare to tell me the polarity of the plug or the trigger threshold voltage, claiming every model is different and there are absolutely no standards. See here. Professionals, sheessh, who needs em?

[PHOBoS]

The output level of the NE555 chip will be just a bit below Vdd but this depends on the current you're drawing from it. According to the datasheet a high output will be 12.5 V @ 200mA, 13.3V @ 100mA (that's at Vdd = 15V) but a strobelight is not going to draw that much so it will probably be higher then 13.3V. There is no problem in using the circuit as an external unit (I also have it in one of my strobe controllers), but if you are gonna use the optocoupler for extra safety, you have to use a separate powersupply (9V wall wart would work fine) so that there are no electronic connections between the circuit and your synth (except for the optocoupler input of course).

I took a look at the controlbooth.com forums and have to say most answers are pretty decent, but the "just buy it and figure it out yourself" does sound a bit harsh. Let's see if I can add some more information.

[macumbista]

[PHOBoS]