High voltage generator II
This project is to demonstrate how high voltage can be made from the 12V Battery. This is done in your automobile to fire the spark plugs. It is done on the farm to electrify fences so that cattle and hogs will stay within bounds.
One way of testing for the high voltage produced with this circuit is to use a neon tester. The neon tester has a small neon lamp and series resistor to limit current. The neon gas requires about 90V before it can give a visible glow. This HV (high voltage) generator cannot give out enough energy to shock any one, but it can cause a neon tester to glow with a dim glow.
The Relay is connected like a doorbell buzzer to obtain square-wave pulses of DC voltage across the series connection of the 100uF Capacitor and Output Transformer winding. This causes the charging and discharging current of the Capacitor to flow through the few turns of the Output Transformer winding.
Because of transformer action the change of primary current generates a voltage in the secondary winding of the Transformer. The secondary winding has more turns than the primary winding (as used here) so the induced voltage is higher than the primary voltage of 9 volts. If the Batteries are fresh enough you may be able to feel the high voltage pulses by touching both probes at the same time. Happy zapping!