Do it yourself cheap - High Speed Flash Trigger

Started Aug 18, 2010 | Discussions thread
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gabgon Regular Member • Posts: 235
Do it yourself cheap - High Speed Flash Trigger

I guess it is my time to share something with the rest of the people on these forums. I'm not sure if this has already been shared here before, but I figured I would share my positive experience with this little invention.

I wanted to try some high-speed photography and googled something I could build cheaply. I read somewhere that you could pretty much use an old tape player or anything else for that matter that would allow you to record and let you hear what you were recording at the same time as a sound trigger. I will explain a little more.

If you can get anything like a camcorder, tape recorder, or anything else with either a built-in microphone, or an input for a microphone while also having output for earphones, then as long as this device will let you hear what you are recording (while being recorded of course), then you have an effective sound trigger.

Knowing this, I went out to the local swap meet and took a computer microphone with me and some earphones. I came across some old tape recorders that didn't work and finally found and old fisher price karaoke machine for children that would allow me to plug-in a microphone and that had an earphone jack.

This is what I bought

Hey don't laugh, it really works!

What you do next is plug in a regular computer mic like this to it.

I then decided that it was time to open up and old flash unit and solder a 1/8” earphone cable to it so that I could plug it into the earphone output of the unit. That's pretty much the only modification I had to do. If you already have a flash that you can plug a 1/8” cable to it, you're all set.

Here's my friend April holding the finished product.

All you have to do is plug in the microphone to the karaoke, plug in the flash to the earphone jack, and when the microphone hears a sound it fires.

What can you do with this? Well, imagine you want to take a photo of a popping balloon. All you have to do is take your camera and set it in manual for say 1 or a 2 second exposure in a dark room, place the microphone close to the balloon and as soon as your microphone picks up the popping the flash will fire exposing your photo!

You must keep two things in mind. YOU SHOULD NOT USE A FLASH WITH A HIGH SYNC VOLTAGE AS THIS MIGHT BURN UP THE GADGET YOU ARE USING TO TRIGGER THE FLASH. I knew that this flash I had didn't have a high sync voltage because I had already tested it. Many of the flashes sold on ebay have very high sync voltages even if they are the same model that I'm using here, so you have been warned and you are on your own. Your best bet is to use something in the 5Volt range.

Second, if I'm not mistaken, sounds travels at a rate of 750 feet per second. So if your trigger is firing a little soon, or a little late, all you have to do is move your microphone either a few inches closer or farther from the sound source.

In the next photo my friend Jose is ready to pop balloons. So he is sitting across from a flash that is pointed away from him and aiming at a white-board that acts like an umbrella. I'm sure the umbrella would have been better as it would have reflected more light. Next to the flash is the microphone that will pick up the sound of the balloon popping and trigger the flash. The unit that makes it all possible is on a nearby chair. Yes I know these aren't fancy looking photos, but I was just trying out the unit and making sure it worked. My friend April was manning the light switch so that we didn't have to work in the dark between shots.

Here's a photo of the setup.

Finally here's a few shots of the balloons popping and proof that the unit works.

Lastly, we added a little bit of water to the last two shots. See the unit works! I told you not to laugh!!!

Lastly, I will say this. If you are really interested in doing high speed photography. I would seriously recommend buying a monobloc or head and pack system with really short flash duration so that you will have as much light as you really need for this type of work. In either case, you can use this little invention to a trigger those lights anyway. Hope you found this useful!

There's not 2 but 3 sides to every story. Theirs, yours, and what really happened.

 gabgon's gear list:gabgon's gear list
Nikon D3 Nikon D3S Nikon AF Nikkor 50mm f/1.8D Nikon AF Nikkor 85mm f/1.4D Nikon AF-Nikkor 80-200mm f/2.8D ED +3 more
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