Presented here is a circuit for 30V 10A variable bench power supply that offers variable voltage and current adjustment. Power supply is based around a LM723 voltage regulator chip and has current limiting. I often end up with the power clips shorting out on the bench and with no problems. I have had this circuit in use now for over 20 years and has never let me down and is one of the most handiest gadgets i have built. The 2N3055 transistors are a well proven high current transistor. More 2N3055 transistors can be connected together for more output current. The transistors will need to be mounted on a good size heatsink.
The bridge rectifier can also be mounted on the heatsink to.
For this reason i mount them off the board and wire to them.
The capacitor bank on the input side can be changed to a single large cap if you have one suitable.
The 5 watt resistors will run rather hot under high load and need to be mounted with air flow around them.
I have often soldered them direct to the pin of the transistors with the other leg connected together and wired back to the board.
When purchasing the 2N3055 transistors ask for them to be all the same batch number as this will help eliminate internal differences.
The pot values shown might need to be changed to allow adjustment over the desired voltage range and current limiting range. A test with the output leads shorted together will soon show max current settable range.
A suitable transformer for the amps required will be needed. It is a simple circuit with a hand full of components.
The only need for a pcb is for the LM723 and the 3 small resistors and 2 caps. The rest is mounted to the heatsink or front panel and wire connected.
Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings.
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tests many different types of transistors such as NPN, PNP, FETs, MOSFETs, Thyristors, SCRs, Triacs and many types of diodes.
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