The basics of a Strobe/Flash circuit.

[turbid]

I just want to make sure I have this right, I have been doing alot of reading and looking at sample circuits, but I just want to make sure I have this right.

I want a simple circuit to fire a zenon flash tube when triggered. I don't need it to strobe or do anything else fancy.

So basically I need;

A DC/DC transformer so get me up to the voltage required by the flash tube.

A storage capacitor

A flash tube

A way to trigger the flash

Is that the basics of a safe flash circuit?

I've seen mention of something I think that is called a trigger capacitor, what is that?

 

[Sceadwian]

Once the primary capacitor is charged to it's desired state you need to initiate the spark so the tube will conduct. A trigger cap would be of a much lower value but charged to a higher voltage to initiate the arc, then the primary cap provides the bulk of the current.

 

[turbid]

Once the primary capacitor is charged to it's desired state you need to initiate the spark so the tube will conduct. A trigger cap would be of a much lower value but charged to a higher voltage to initiate the arc, then the primary cap provides the bulk of the current.

Ah, OK. THanks

I'll go look at some more schematics now and see if they make more sense.

 

[Sceadwian]

I could be wrong but that's my best guess =) The stupid simple flashes on disposable cameras I've taken apart trigger the discharge by applying the HV positive to a shield that surrounds the discharge tube, causes a brief internal arc to the side of the tube which ionizes the gas inside and causes the flash.

 

[dougy83]

A way to trigger the flash

Normally a trigger transformer & trigger capacitor. To trigger the transformer you can use a neon, diac, neon + scr, a transistor, a switch... well there are many different ways to trigger it.

I've seen mention of something I think that is called a trigger capacitor, what is that?

The main bulk capacitor stores the flash charge and applies it to the internal terminals of the flash tube. There's a smaller cap that is charged from this and is discharged through the trigger transformer primary to create usu. 1-6kV to the outer electrode which excites the gas and allows the main flash arc.