This is a reverse engineered circuit diagram from an expensive commercial variable lab power supply. The unit is designed around an ordinary op-amp and easy to obtain parts. Although the unit uses a single transformer with two output windings the circuit works equally well using a big transformer and a little transformer. The test point [...]

For you who like antiques or the circuit is old, use old equipment comes to experience build is usable can jubilantly And still have an experience that good with. As a result should try build 0-30VDC Variable Voltage Regulator lap supply circuit. [...]
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For the work experiences electronics circuit of me. Several times at must experience the circuit that use power supply units 12V both of sizes are positive and negative Voltage or +12V GND -12V. I will choose to use this circuit. It uses integrated pair readymade circuit number LM7812 [...]