I just read an article about using a camera's flash cap for an emp. It said that the cap can charge to voltages up to 300v. How can 3v from 2 AA batteries charge a cap to those voltages?

 

Magic, clearly.

But seriously, look up voltage multipliers.

 

I just looked it up. Everywhere I looked said that voltage multipliers are used to amplify an ac voltage to a dc voltage. A camera uses dc. How would this work?

 

It runs a DC-powered oscillator to create AC, which is then stepped up.

 

This?
Max..

 

Yup. I could never draw such a thing from memory but it looks about right once I see it.

 

I just looked it up. Everywhere I looked said that voltage multipliers are used to amplify an ac voltage to a dc voltage. A camera uses dc. How would this work?

Probably a simple boost converter. The current is very low.

 

It uses a simple transistor oscillator to drive a transformer, which boosts the voltage up significantly. This is what charges the capacitor.

I wouldn't expect an "EMP" gun built from a camera flash circuit to be able to do damage to much more than, say, a small calculator.

Regards,
Matt