adjustable voltage regulator

Adjustable Voltage Regulator with TDA2030

This Adjustable Voltage Regulator is made by combining a common 78L05 with an integrated audio amplifier of the type TDA2030, an adjustable voltage regulator can be constructed in a very simple manner that works very well. The output voltage is adjustable up to 20 V, with a maximum current of 3 A. Since the TDA2030 comes complete with a good thermal and short-circuit protection circuit, this adjustable regulator is also very robust.

As illustrated by the schematic, the design of this circuit is characterized by simplicity that is hard to beat. In addition to the two ICs, the regulator contains actually only two potentiometers and a few capacitors.

The adjustment is done by first turning potentiometer P1 to maximum (wiper to the side of the 78L05) and subsequently turning trimpot P2 until the desired maximum output voltage is reached. P1 is then used to provide a continuously adjustable voltage between this maximum and nearly zero volts.

At relatively small output currents there are no specific requirements regarding the cooling. However, when the output current exceeds 1 A, or if the input to output voltage difference is quite large, the amplifier IC has to dissipate too much power and a small heatsink is certainly appropriate.

Variable Voltage Regulator Circuit Diagram

adjustable voltage regulator


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  • OR

    ^ Do you really use this circuit?

    TDA2030 normally has many sub versions but 36v of single supply is the maximum. The problem is that the circuit is not designed properly. The output capacitor can also be a problem if it discharge TDA2030 and it will function as a short wire when the circuit starting ( as capacitor needs to be charge ). The protection circuit and output rating also are specified by AC mode not DC.

    Using two transistors will be cheaper than using TDA2030. The second transistor will also work as current limiter. I thought that you can find the circuit like that easily on the net as it is so common in design theory.

  • Willail974


    Thank you for this circuit!! I have built it but i’ve some problems on the TDA2030. This electronic part heats a lot so it burns after 45seconds. I’ve destroyed 2 TDA2030. Are you sure that TDA2030 can be supply with 19V (measured voltage after a bridge of diodes).

    Is it possible to decrease the supply voltage of TDA2030 with a resistor or any circuit to built.

    Thanks for your help

    PS ; sorry for my bad english

  • Tom


    use 2 suuply in series.

  • mamad

    This is a great idea, but it is limited to 20 to 30 volt for about 3 amps.
    How about if we go up to 55 volt /10 amps

  • cezar


    This is an excellent and noble design idea, the TDA provides the fold back current limiting instead of a transistor that have no thermal shut down, the current capacity is also quite decent.
    Thank you and Congratulations for this great idea.
    This will make a good addition to my list of great electronics design ideas.

    More power.


    I think that a PNP power transistor is a lot cheaper than an amp of that calibre

  • imayoda

    usefull, many thanks 🙂

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