12V DC Power Supply without Transformer

12V DC Power Supply without Transformer
These are 12V DC power supply circuit which designed without transformer (trafo). These circuit use capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's

6.8 Volt Transformerless Power Supply.

6.8 Volt Transformerless Power Supply.
Quite a simple power supply unit can be built for half an hour. The scheme is designed for voltage and current of 6.8 V 300mA. The voltage can be changed by replacing the Zener D4 and, if necessary, D3. A setting on the radiators of transistors can be increased and the load current. Diode bridge - any, is nice and a reverse voltage of at least 400 volts. By the way, we can recall the ancient and diode D226B,

Mains AC / DC Converter with SR03x

Mains AC / DC Converter with SR03x
This is another Transformerless power supply.  IC voltage regulators for SR03x made ​​by Supertex is connect directly to main voltage and get the output voltage to 3.3V and 5V chip for SR036 SR037 to 30mA output current. To use this chip is not necessary to use step-down transformer or coil. Rectified input voltage to the diode bridge diodes D1 - D4 (figure point a) is input circuits IC1 SR03x. (more…)

Transformerless power supply FET

Transformerless power supply FET
The circuit shows a diagram of a simple transformerless power supply for transistor BUZ41A. Through the inclusion of the common-drain transistor VT1 NW capacitor charging to a voltage of about 3 smaller than the zener voltage of VD4. An alternating voltage with a phase shift, determined by the capacity of the capacitor C1, transistor opens VT2, which stops the charge capacitor NW at the beginning of each positive half-wave supply voltage. (more…)