Wednesday, February 2, 2011

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12 Volt Transformerless Power Supply

This transformerless power supply circuit will of supply up to about 20mA at 12 volts. It uses capacitive reactance instead of resistance, and it does not generate very much heat.The circuit draws about 30mA AC. If you need more current, use a larger value capacitor, or put two in parallel, but be careful of what you are doing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2. The bridge rectifier cans be any of the small 'Round', 'In-line', or 'DIL' types; or Could you use four separate diodes.
12 Volt Transformerless Power Supply Circuit
This power supply can not be modified to Provide currents of greater (can not be up to several amps). The circuit was Designed to Provide a cheap compact power supply for Cmos logic circuits require only A Few That milliamps. The logic circuits were the resource persons then Used to control mains equipment (fans, lights, heaters etc.) through an optically isolated triac. If More Than 20mA is required it is possible to increase of C1 to 0.68uF or 1uF and thus obtain a current of up to about 40mA. But 'suppressor type' capacitors are Relatively big and more expensive Than Regular capacitors; and Increasing the current That means higher wattage resistors and zener diodes are required. If you try to Produce More Than about 40mA the circuit will from no longer be cheap and compact, and it simply makes more sense to use a transformer.

List componet of 12 Volt Transformerless Power Supply
C1             : 470nF/500V
C2 : 100µF/25V
R1 : anything from 1MΩ to 10MΩ
D1, D2, D3, D4 : 1N4007 or rectifier 230V AC
D5 : zenerdiode 12V or matching Uout desired

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