DIY Digital Slave/Strobe

[JBowl0101]

Hi all:

Just in case anyone was interested, I wanted to post my current project. I determined I needed a strobe for my Canon A520 before my August trip, but did not want to drop $300 or more for a commercial unit, so I decided to build one.

The flash unit is a standard "dumb" external flash unit ($15 on ebay), triggered by an Atmel AVR circuit which counts the flashes from the camera, and then fires the strobe after the camera's metering preflash. The circuit is a composite of some other designs I found on the web, and the code is mine, since I happened to have an AVR in my junk box.

The housing is an Otterbox 2000 - probably could have crammed it into a 1000 if I had been more careful.

If anyone is interested, I can draw up schematics and post my code. It works very reliably. I'm sure if you had access to a lathe you could make a much nicer housing, but I was going for the simplest, cheapest approach I could. I should have it in the pool for testing shortly - I fired it underwater in my sink for the first time yesterday.

Photos are at:

http://tinyurl.com/kn5ga

If anyone wants schematics and code, please let me know.

Jason

 

[hilk]

Hi all:

Just in case anyone was interested, I wanted to post my current project. I determined I needed a strobe for my Canon A520 before my August trip, but did not want to drop $300 or more for a commercial unit, so I decided to build one.

The flash unit is a standard "dumb" external flash unit ($15 on ebay), triggered by an Atmel AVR circuit which counts the flashes from the camera, and then fires the strobe after the camera's metering preflash. The circuit is a composite of some other designs I found on the web, and the code is mine, since I happened to have an AVR in my junk box.

The housing is an Otterbox 2000 - probably could have crammed it into a 1000 if I had been more careful.

If anyone is interested, I can draw up schematics and post my code. It works very reliably. I'm sure if you had access to a lathe you could make a much nicer housing, but I was going for the simplest, cheapest approach I could. I should have it in the pool for testing shortly - I fired it underwater in my sink for the first time yesterday.

Photos are at:

http://tinyurl.com/kn5ga

If anyone wants schematics and code, please let me know.

Jason

nice idea... do you mind post the code schematic here ???
thanks

 

[JBowl0101]

It will take me a couple days to find time to draw up the schematics, but sure, no problem.

 

[Firecracker]

Sounds good...I'd like to take a look at it too.

 

[JBowl0101]

OK, I got the slave strobe in the water with my A520 - I had to wait forever to get the housing for the camera.

Pictures of the physically completed slave flash are at the link I gave above.

The circuit works very reliably on land, but under water it will only work if I'm shooting something less than about 5 feet away. I'm thinking the water is diffusing the bounced light so much the trigger circuit is not picking it up reliably.

I'm going to experiment with the biasing on the trigger circuit. If that fails, I'll just put the photodiode on a wire that goes through the gooseneck and clips to the side of the camera housing, which would put it less than an inch from the camera flash.

I'll keep you posted.

Jason

 

[Firecracker]

Sounds good so far, Jason.

Do please keep us posted.

 

[cfelliot]

Jason,

I built a similar setup last year for my Canon A75. I also experienced some of the same problems you note.

See my first shots at: http://www.chuckelliot.com/kauai_scuba.htm Most times the flash didn't fire, but see the difference between the 2 turtle shots!

I used a Pelican case and sealed it with silicon.

The new version is going to be built around a acrylic tube I found, poured acrylic and an O-ring.

Light is coupled between the two unit via a tos-link cable I have and the cases from 2 tos-link transceivers.

Chuck

 

[JBowl0101]

Thanks Chuck. Glad to know it can work. I'm planning on building a smaller prettier version at some point too, but decided it should work first.

I opted for a remote sensor - I mounted the photodiode on the end of a pair of wires snaked through the gooseneck that will tack to the outside of the camera housing with a supermagnet or velcro. That should make it extremely reliable. I'll have it back in the water on Monday for more testing.

Side effect - the lifeguards think I'm an absolute freak after I sank a traffic cone in their pool at 15 feet and then spent 30 minutes freediving down and taking it's picture. The price of science.

 

[JBowl0101]

Chuck:

Love the turtle! Do you have any photos of your flash?

 

[cfelliot]

Here's the whole old unit. I'm working on the new one. As you can tell I'm a PVC fan

Chuck