This project is a simple variable power supply using the famous
LM7812 regulator IC. It consists of two boards, the main board which
includes the regulator, capacitors, bridge rectifier and
potentiometer and a second board that includes the mains tranformer,
the fuse and a switch.
I designed this variable power supply which is based
on the famous series of voltage regulator LM78xx.
The electrical characteristics can be found
here. LM78xx can be easily found in stores with
On this project I use the LM7812 in TO-220
footprint, which can be screwed to the rear of a
heatsink for better heat dissipation. You will get
better heat conduction if you use thermal paste
between the heatsink and LM78xx before screwed
The bridge rectifier is a classic
2KVV. You may choose the appropriate bridge
rectifier according to your requirements.
The variable resistor R3 varies the output voltage
(Vout). The R3 can be placed in your project box and
can be replaced with a potentiometer of similar
The second board is for the transformer, the board
contains the base for the primary fuse and one
on-off switch for 220V mains voltage.
The main power supply for t
Eagle CAD PCB layout
3D PCB renderings
files in Eagle format
Download Regulator board Gerber files
board Gerber files