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Return to Blog1.25V to 25V 1.5A LM317 Power Supply
Posted Jan 14, 2012 at 3:24 pm
Figure 1
This simple LM317 (three terminal voltage regulator) power supply is giving an adjustable voltage output of 1.25V to 25V and capable of delivering 1.5A. You can adjust the output voltage by turning the 5 kΩ potentiometer.
A 250V – 3A fuse is connected to the input to protect the circuit against high voltage.
The T1 transformer is 220 VAC to 25 VAC. A 100V – 1A bridge rectifier is ample to handle the current.
A quite large heatsink must be connected to LM317 to dissipate the excess heat. You should apply thermal paste between LM317 and the heatsink.
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2 years ago: I used this type of power adapter on my old nintendo family computer. It lasted longer than the nintendo itself haha!
2 years ago: maybe adding more fuse can give better protection right?
1 year ago: nope, if you add more fuse to the circuit, the tendency will be - if a surge in the electric current happens, fuses will just allow more current to the circuit which is dangerous and can destroy your components, so better have a fuse that can tolerate the current rating of the circuit or the one that was stated on the schematic...