Laser Triggered High-Speed Photography

Step 3: The Circuit

At the bottom you'll see a link to a pdf containing the schematic.

To trigger your CHDK enabled camera we'll be using the USB remote function. In this case we have to use it via the 'syncable' method, which is lightning fast compared to the normal USB remote.

The syncable remote also operates differently. It triggers the camera on the falling edge instead of the rising edge of the 5-volt signal. When the camera detects the 5 volt USB signal, it gets ready to take a shot, waiting for the voltage to fall to zero.

There are high-speed camera trigger circuits floating around the 'net but I couldn't find any for syncable USB. So I cobbled together the circuit below.

It uses a 556 timer IC, an inverter, a photoresistor and some caps and resistors.

The dollar store had a USB cable identical to the one my camera uses. I lobbed one end off of it, instead of wrecking the one that came with my camera.

A 5-volt power supply is needed to power the circuit. If you don't have one, pick up a cheap USB charger, or add a 7805 voltage regulator to the circuit.

The photoresistor is not on the circuit board; it's mounted on a small piece of perf board at the end of a short cable. Glue some magnets onto the back for easy alignment with the laser.

The circuit should be built first on a bread-board and tested. Once you're sure everything is working then either etch a circuit board or use a prototype board like I did. Or just continue using the circuit on the bread-board.

NOTE: OCT 2nd, 2009 There was a huge mistake in the schematic that instructable member toxoof pointed out. The PDF has been corrected.

OCT 19, 2009: another error has been found in schematic. Arrrggggg!

July 30, 2010: Schematic revised to use photoresistor

Download the pdf here: Schematic

Revised 2 schematic.pdf1 MB

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drivera1 says: Apr 6, 2011. 8:46 AM

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harshads says: Oct 12, 2009. 9:42 PM

i have a sony cyber-shot camera and less likely to obtain a canon.......please post the method with a sony cyber-shot camera.
i will be very gratefull

natsfr in reply to harshadsDec 19, 2009. 9:29 AM

HI,
I just just did it with an Alpha 700 from sony,
give me your cybershot model, maybe it's the same connector for remote command :)

(I'll write a little how to for the alpha)

Frivolous Engineering (author) in reply to harshadsOct 13, 2009. 7:07 PM

The circuit is designed to work with a USB remote and a CHDK enabled camera. And the camera is armed prior to taking a picture, enabling the shutter to be triggered in only 5 -10 miliseconds.

While it may be possible to do this with another brand of camera, I don't have a Sony camera with which to test any modifications to the circuit. I really would like to help you but I can't safely make any recommendations.

CAUTION: BLATANT VOTE PANDERING FOLLOWS:

This instructable is entered in the Digital Days Photo Contest, and a Cyber-shot is the top prize. If I should happen to win that camera I will be ABLE to test a modified circuit. So please VOTE for this instructable and if I win, I will do my best to post an instructable using the Cyber-shot.

-Brett

lfcrule2 says: Dec 5, 2009. 7:00 AM

You think it's possible to modify a shutter remote with this so that I can trigger my film slr?

Frivolous Engineering (author) in reply to lfcrule2Dec 9, 2009. 2:17 PM

It's possible, but there is more to it then just that. The flash would need to be a Speedlite, and you would have to mod it, to reduce the duration.

This set-up really depends on having a Cannon camera that's compatible with CHDK.

txoof says: Oct 1, 2009. 4:15 PM

I would like to try to hack this to work with my Olympus E510. I built a remote shutter release that basically just brings two of the pins in the jack to ground and that fires off the shutter. Can you offer any advice as to how I could modify your circuit to do the same thing? I'm not terribly savvy when it comes to anything more complex than a super basic circuit like the one I built for my shutter release, but it seems like I should be able to either make a relay (seems slow) or something that does the same job to make this work for my camera.
Any ideas would be greatly appreciated!

Link to my shutter release: http://www.instructables.com/id/Olympus-Evolt-E510-Remote-Cable-Release-Version-2/

Frivolous Engineering (author) in reply to txoofOct 1, 2009. 5:52 PM

Let me send you a pm!

txoof in reply to Frivolous EngineeringOct 1, 2009. 9:50 PM

I think there's a way to do this sanely (I have an EE helping me), but I have a slight problem with your schematic and parts spec. C3 is listed twice as two very different caps; there is no spec for C7 and C8. Perhaps the info is somewhere else correctly, but the PDF is incorrect, or I'm having a stupid moment while reading it.

Frivolous Engineering (author) in reply to txoofOct 2, 2009. 4:40 AM

Very glad you caught my BIG mistake! The second C3 is actually the missing C7 While going the circuit a second time I also noticed that I got the values of each reversed C1-C3 are all 1 uF and C4 - C7 are all .01 uF. The circuit would still have worked but most there would have been very little adjustment to the delay. I've corrected the schematic. My apologies to everyone for this huge blunder.

dr_3soma says: Oct 1, 2009. 8:04 PM

Dear\ SaskView Very Nice instrutable but i'm asking about the circute and the laser trigger could be installed with flash (Professional FLASH) so the laser trigger will release the flash instead of camera and the trigger could be suitable for DSLR Professional Cameras like Nikon D80, Waiting for your reply and thanks again Essam

Frivolous Engineering (author) in reply to dr_3somaOct 1, 2009. 9:02 PM

This is going beyond the original intention of this instructable. While it should be quite easy to do, I don't have an external flash to test it with. I'm sorry :-(

Thav says: Oct 1, 2009. 9:18 AM

Pretty neat. If you're worried about damage to the USB connector on the camera you can add two schottky diodes to shunt away transient voltages from the USB connector. It's probably not necessary with this circuit since it is pretty simple but it's an extra precaution. You would want to place the diodes as close to the connector/cable as possible. If that's far away from your main circuit, consider adding a 0.1uF ceramic cap from +5V to ground near the USB connector.