How do Stun Guns get 900,000 Volts out of 9 Volt Batteries?

Question

I know they have some kind of voltage boosting circuit but I can't understand it.

Answer 1

The circuit is generically called a DC to DC Inverter or perhaps just an Inverter if the output is not DC. The word "inverter" comes from the fact the DC power source (the battery) must first be changed into an AC power source.

Op-amps are not used. In nearly all cases, a transistor switching circuit is used to create an AC square wave from the battery power.

There are three methods I know of. 1) Inductive flyback, 2) step up transformer, and 3) transformer + diode ladder.

1) As with an automotive ignition coil, if you put a current through an inductive coil & then suddenly open the circuit, a large voltage will develop across the coil. I think this is the most likely one.

2) Feed the AC square wave into a step up transformer and optionally rectify the output.

3) Same as 2) except the transformer output is fed into a network of diodes that increase the voltage by another large factor (5 to 50). The diode network can handle higher voltages than a medium sized transformer.

Answer 2

You probably can't understand how a motor vehicle's ignition system gets several thousand volts form a 12V electrical system either ....... or an electrified fence which works in a similar manner. Or a t.v. receiver with a c.r.t. which has voltages in the region of thousands which is derived from the domestic mains supply.

They all use either a.c. or pulsed d.c. which is applied to a transformer.
A transformer can be designed to produce a secondary voltage lower or higher than that applied to its primary.

Answer 3

a capacitor and a step up transformer or amplifier... probably an OP-amp is used.
the higher the voltage increase the lower the current.
50,000V I believe is what they use not 900,000V

Answer 4

it`s called a step up transformer

Answer 5

it is a capacitive discharge I think