Wagner Lipnharski says:
Diode .------>|------------o---o High V | | 3| <- point A | 3| --- HV C 3| --- 3| | +1.5V----o------------------3| <- point B | | 3| GND R 3| | Nc----------3| <- point C o------P 3| | Ne--. 3| | | 3| <- point D | GND | | | '---------||--------' CThis circuit use a "one coil" transformer with two taps. At power on, all points have the same +1.5V.
- Resistor R makes the NPN transistor conducts
- Current Flows from ground to point C, via coil to B to +1.5Vdc.
- Point C is grounded
- Point D will develop a voltage below ground
- Point A will develop a voltage higher than +1.5V.
- Voltages goes increasing
- Voltage at point D is enough negative to cut off transistor via capacitor C.
- Transistor opens, Point C goes floating.
- High + Voltage at Point A is rectified and stored at HV C.
- Capacitor C (blocking the transistor) starts to discharge via R and coil taps D-B.
- Upon C discharged, R is enough to turn on transistor again.
Cycle repeats in a frequency determined by R, C, and the transformer itself.
This kind of configuration was widely used, using a cheap small transistor audio output transformer (transistor radio), connecting the secondary in series with the primary.
file: /Techref/power/transformerchargepump.htm, 2KB, , updated: 2009/10/1 15:51, local time: 2024/8/14 23:30,
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Ashley Roll has put together a really nice little unit here. Leave off the MAX232 and keep these handy for the few times you need true RS232! |
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