CEMF Charger

The CEMF charger uses the CEMF (counterelectromotive force) from an inductor to charge a capacitor to high voltages from a low voltage source. A simple schematic of a CEMF charger is shown below. 


 ==========
|^^^^^^^^^^|
|          |
+-|>|-+-||-+--o -
|     |    |    High Voltage
 /    +----|--o +   Out
|          |
+--o    o--+
   -    +
Low Voltage
     In

  |
--+--  Wires connected
  |

  |
--|--  Wires not connected
  |

|
 /  Push button N.O.
|

When the button is pushed the inductor will generate a small amount of CEMF that will charge the capacitor (the CEMF generated is of opposite polarity to the source, so the diode allows only the CEMF to get to the capacitor). When the button is released the inductor generates more CEMF that charges up the capacitor further. After many cycles of pushing and releasing the button the capacitor will have a considerable amount of energy stored (up to 400V or more using an electrolytic, or 1kV or more using a non-electrolytic). To simplify the charging process a pulse generator can be used in place of the push button. And in order to get higher voltages faster, use an inductor with a high inductance (1H or more work good), and the time between changing states (from on to off) should be as short as possible. And for a powerful output use an electrolytic capacitor, or for a higher voltage output use a non-electrolytic.

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