Aiming to improve the image quality of the photos on his website, [Jean] needed an external flash unit.
Say what you will about disposable cameras, but the fact that they were mass-produced, and are now nearly obsolete, means they are an absolute treasure trove of electronics components when you can buy them for dirt cheap. So [Jean] decided to turn a few of his disposable cameras into an external flash system for his DSLR (Translated).
He started by taking apart a Kodak digital camera and examining the circuit board. KEY1 enables the charging of the capacitor (the camera ON switch) and SW1 is located under the shutter-release.
Now all he had to do was replace SW1 with an electronic trigger from his DSLR.
To do this he built a custom circuit based on a triac and an optoisolator as shown below:
This isolation ensures the circuit does not get damaged from the capacitor when triggered. Finally he made a PCB that would fit in his DSLR’s hotshoe adapter to accept the 5V trigger — and that’s it!
Speaking of camera flashes, while you’re at it — why not build a $2 high-speed laser camera flash sensor for high-speed photography?