Complete power supply module, requiring only a network transformer. The module includes a rectifier, capacitive filter and stabilizer. The potentiometer is used to adjust the output voltage.
• Input power supply: 5-20V AC or 5-30V DC.
• Output voltage: 1.25-25V DC.
• Maximum output current: 1A.
• Includes rectifier, overcurrent ant shortcut protection.
• PCB dimension: 30×50mm.
• Electronic Kit – soldering required.
Figure 1 shows the schematic of the stabilized power supply with LM317 integrated circuit. The rectifier bridge M1 rectifies the alternating voltage from the power transformer. When powered from DC power supply, the bridge prevents the input voltage from being inverted. Capacitor C1 filters the input voltage of the stabilizer. The stabilizer works in a typical application. The resistance R1 / R2 + P1 is responsible for setting the output voltage. The resistance values shown in the schematic allows to set the output voltage up to 25V.
It is sufficient for most applications. The maximum output current of the stabilizer is 1.5A, but it depends on the size of the heatsink. Notice, that at low output voltage and high current, the US1 chip will dissipate power. This power should be dissipated through the heatsink.
Assembly and test
Figure 2 in user manual shows the assembly diagram. Assembling such a simple module will not cause a problems and the ready-made power supply does not need to be adjusted. Without heatsink the US1 stabilizer is able to dissipate power up to 2W, therefore the output current have to be as low as 0,1A. With the heatsink delivered with the kit, the maximum output current is 1A.
In place of the mounting of the trimmer P1 conventional potentiometer or a switch with a suitably chosen resistors can be connected by wires. In order to obtain a voltage regulation range from 1.25V, place a wire instead of R2.
P1: Trimmer potentiometer 5kΩ
B1: Bridge rectifier
IN, OUT: 2-pin terminal block connector