trying to build a simple flash circuit to be used in making an external flash for camera.

Thread Starter


Joined Mar 28, 2016
So I've been trying to figure out how to build a flash to make an external flash unit for a camera. I have learned a lot about electronics and especially about how a basic flash circuit works but am still trying to figure out some basics as I have no background education toward electronics whatsoever. Hasn't even been a hobby until now.

I looked up a lot of info online and figured out how most of a flash works but I'm still figuring out how some of the other parts work.
In this article here it explains how major parts work and then says the other parts in the circuit are fixed components and doesn't explain what they are doing. That just so happens to be the part I would like to know.

I'm guessing that the trigger transformer in the circuit still needs an AC current to work and that is the purpose of the other transistor? I know the other capacitor is there because the trigger transformer has an input voltage of a few hundred volts.

My ultimate goal is to make a basic flash like this but with an LED indicator light for when the main capacitor is full and not to have it triggered optically but with a hotshoe that can be connected either the the camera or with a remote trigger. But for now just trying to increase my understanding of this type of flash. Help is much appreciated.

And please don't belittle me and my newbie efforts by telling me to learn more about electronics before trying to tackle a circuit with some dangerous components on it. I'm fully aware of the dangers here and understand not to touch metal parts with hundreds of volts circulating through them or to go connecting resistors that aren't rated for the voltages in the different parts of the circuit. I'm just trying to increase my understanding so that when I'm ready I can build one without problems. Thanks for the help with my project and for furthering my knowledge.


Joined Sep 17, 2013
As mentioned on another forum, this is NOT a project for someone with little electronics experience. Any small error could be FATAL. This advice in no way belittles you. While you may be aware of the hazards, other readers of these posts may not.