Presented workshop power supply is an adapter to the typical power supply. The regulator based on a well-known stabilizer LM317. Multiturn potentiometer allows precise setting of the output voltage, which is indicated by a digital voltmeter.
• Supply voltage within range 5-18V AC or 5-24V DC.
• Output voltage 1.25-20V DC.
• Maximum output current 0.5A.
• PCB dimension: 60×110mm.
• Electronic Kit – soldering required.
The schematic diagram of the workshop power supply is shown in Figure 1. The output voltage is stabilized by well-known integrated circuit LM317. It is protected against shortcut and overheating. The output voltage can be precise set in the wide range by multi-turn potentiometer used instead of two – one for course and one for fine adjustment.
The workshop power supply can be used at input voltages up to 24V and output current up to 0.5A. To obtain the maximum parameters for the stabilizer, in example output current of 1.5A, it is necessary to use a power supply of several tens of watts and a large heat sink. By using a rectifier bridge, the device can be powered by a non-polarized or alternating current.
For the measurement of the output voltage, a universal voltmeter module is used. It measures voltage up to 99.9V. The voltmeter is powered by a DC voltage from 3V to 30V. Three output connectors – banana socket, goldpin 2x5 strip and double spring connectors allow easy connection of the powered device.
Assembly and test
Practical workshop power supply should be assembled on PCB shown in Figure 2 in the user manual. The assembly is typical and should not cause the problems. It runs in standard way starting from the smallest components and ending with the largest ones.
There are two power supply connectors on the PCB that are connected together. Therefore it does not matter which connectors supply power, which makes it possible to connect using a DC 2.1/5.5 or 2.5/5.5 plug or power supply cables. To fix the plate use four screws.
PR1: Precision potentiometer 5kΩ
D1, D2: 1N4007
X1: DC 2.1/5.5
X3: Red banana socket
X4,5: Goldpin connector 2x5pin
X6: Black banana socket
MOD1: Voltmeter module
Heat Sink: DY-CX