stabilized power supply circuit schematic

Stabilized Adjustable Power Supply 0-15V/5A

This regulated power supply can be adjusted between a few volts and 15V with P1 and with P2 adjust the upper limit ( 15.0V ). R6 value is 0.7V / Imax where Imax is the maximum current. At Imax = 5A, R6 is 0.14Ω

T1 and T2 must have heatsinks because power losses are great at a low output voltage and a Imax equal current but you can connect the lamp L to reduce this losses.
I’ve build this adjustable power supply and works great! I hope you’ll enjoy it too and have fun build this great stabilized power supply.

Adjustable power supply circuit diagram

stabilized power supply circuit schematic


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  • Godwin Symons

    Your diagram is good but can’t help me.

    I am hoping you might be able to help me with a power supply unit circuit diagram.

    The power supply unit that I have is a Zurich RPS-1012MB variable 15 volt 10 amp adjustable limit. I has gone faulty. I would like to repait it, but all efforts to now have not worked.

    I hope you might direct me to a circuit diagram for my unit or a diagram that I can use to build up a new circuit for my unit.

    • Jim Keith

      I found a photo of one of these units–inside is a massive 50HZ transformer. While there is a large heatsink on the back with two power transistors, it is doubtful that they can dissipate the full 150W with the output terminals shorted–also note that the fins are not properly oriented for convection air flow. My guess is that there is a TRIAC (or antiparallel SCR) voltage pre-regulator in the transformer primary circuit that automatically sets the unregulated DC about 3V above the terminal voltage–this reduces the power dissipation of the series pass transistors by a factor of 5 or so.

      So look inside for the following:
      1. A 2nd small 50HZ power transformer to power the control circuit–probably on the circuit board.
      2. Huge electrolytic capacitor(s) e.g. 47,000uf @ 25V
      3. TRIAC or SCR part number
      4. Optical coupler to isolate the preregulator voltage feedback signal
      5. Series pass transistor part number

      Perhaps this info will help you troubleshoot–the most likely failure points are the TRIAC and series pass transistors (and drivers). A nice feature to add if you are redoing the circuit would be adjustable current limit.

  • wwsly

    Hi, i think, after my experience, that this circuit can not work. It’s better to write> this circuit work from about 2 volts to max.
    If you want regulate out voltage from zerou, you have to use lm258, lm358 or lm10… This are Operating amplifiers whose can work with small voltage on their inputs. 741 need small negative voltage, becase have on inputs PNP tranzistors.
    Sorry for my english.

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