Lighting with flashes can be addicting, but it can also be extremely expensive. Especially when you want to fire multiple flashes at once. But, if you know your way around a soldering iron, there's a DIY hack to keep the cost down. Peter Y Lin put together this hack on his Flickr account, and it's a way of triggering six flashes instantaneously.
Lin has put his together on a PCB, and has included a schematic and a PCB diagram (if you have access to the parts). Once constructed, it's simply a matter of triggering a single central unit, which then triggers the rest of the cluster. Here's how Lin explains it:
Most, if not all, manual radio/optical trigger works by pulling the center pin to ground, creating a short in flash's circuitry, hence triggering the flash. Knowing this, we can use a logic IC with enough buffering capability to drive simple transistors to trigger multiple flashes. Here, I am using CMOS HC logic gate series because
1. it works under wide range of voltage,
2. it has 10+mA driving capability, enough to drive a transistor
3. input impedence is high, so tying up six gates does not create too much burden on the input.
4. it is FAST, response time is usually quoted in nano-seconds
So, as you can see in the schematics, the input is tied up to high so all outputs of 74HC04 is low. When input trigger pulls down the input pin, all outputs become HIGH, thus driving transistors to short.
If you really have more flash guns floating around than you could ever need, this whole rig can be scaled up, too. Lin claims you can combine seven of these circuits to fire a whopping 36 flashes at once.
Seeing as not all of us have circuit printers at home, how long do you think it'll take for someone to slap these in a nice little case, and set up a Kickstarter?