electric mosquito/fly swatter

[cbiblis]

Can someone tell me how these things work? apparently, they claim to charge to 3500v from 2 x AA batterys. How does one step up that much from 3V? Do they use a coil for something like that? I'm just curious.

 

[keny]

Yes do tell. I was thinking about installing something like that on my thermostat so my housemates don't touch it.

 

[Patman]

Fly swatters use a single (or sometimes multiple) high-value capacitors to store energy from the batteries. As with a disposable camera, which also requires hundreds if not thousands of volts to operate the flash, the 3 volts from the batteries are fed into the capacitor bank until thousands of volts are connected to the positive side of the swatter grille. As soon as a fly (or any conductive object) connects the positive and negative sides, the voltage stored in the capacitors quickly travels through the conductor into the negative side. The process repeats as long as there is something shorting the two sides.

 

[Diver300]

The principle is similar to the system used to generate 30 kV for the ignition systems on petrol engines, or in the "Joule Thief" circuit.

An oscillator turns the current on and off, and this current is fed into a transformer, which increases the voltage. In many cases the oscillator is combined with the transformer and it won't oscillate without it. Transformers will not work on direct current, and batteries only produce direct current, so that is why the oscillator is needed.

In the fly swatter and camera flashes, the transformer output charges a capacitor and many thousands of oscillations are needed to build up enough charge for the item to work.

 

[3lectrokid]

its the same thing as a gas cooker with a 1 AA battery creating a big spark - enough to ignite gas

 

[Reloadron]

Give this a read. A simple 555 timer configured as an oscillator driving a high voltage secondary transformer. The linked to circuit uses 6 to 12 volts but with the right transformer and oscillator chip could likely be built to work off 3 volts.

Ron