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voltage regulator extension circuit schematic

78XX Voltage Regulator Extension

With this voltage regulator extension circuit you can increase the output current up to 10 A. T1 power transistor has a resistor in the emitter and thus the transistor’s current is proportional to the current delivered by the voltage regulator.

If the 78XX regulator and T1 are mounted on the same heat sink then the transistor is thermally protected. The output voltage is dependent only on the type of the voltage regulator used in the circuit. With the components presented in the schematic the maximum output current is 2 A. T1 is BD242 but for different values of the output current you need to replace some components (download the table at the end).

Voltage Regulator Circuit Schematic

voltage regulator extension circuit schematic

If higher values are necessary, some components must be changed according to the table presented in the excel file. For currents above 7 A then T1 must be replaced with 2 transistors (T1 and T1*) connected in parallel, each of them having a resistor in emitter, R1 and R1* respectively. Also the bridge rectifier is different.

7 Comments

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  • roger blackman

    Thank you for this circuit, however, when I downloaded it, my Nook was unable to read it. Could you please suggest to me which program you might use to read it. Again thank you for you work.

  • jae msea

    Sir I’m sorry I wanna ask you about my problem with ic regulator 7805 . I have one car battery 12v and 33Ah, I want to use it for my supply in circuit but when I’m using this battery to source power my circuit 10 LED with ic 7805 , i use heatsink too, but the ic regulator 7805 still overheat , how i fix it , sorry sir if it out of topic

    • B.kirubakaran

      Dear jae msea,
      please mention you have used for this project L.E.D Current rating,
      connection Detail series/ parallel.Series L.E.D circuit mean load takes potential and the parallel L.E.D circuit takes Current this important to tell a solution.
      Regards,
      B.kirubakaran

  • DANIEL

    could you give an example of how to connect a power voltafe o-50 V 1A
    And how to connect the voltage regulator TO INCREASE AMPERAGE Extension

  • ashtami

    Oh! This is a happy news!!! After all I’m messed up with my 36v 0 36v 5Amp bridged dual supply..Transformer’s AC out is 36-38v. But the Bridged output comes 110 -120 + and – DC. I’m using 4700/100v Capacitors and 104 poly..
    So It will be a great help, if you publish a DUAL Supply model of this circuit…
    Thanks..

  • ARJUN PRASAD

    I AM NEW USER PLZ LET ME KNOW WHERE IS CKT EXPLAINATION AND AS U SAID WHERE IS EXCEL FILE I CANNOT FIND REPLY PLZ

  • Alexei

    I would say I am impressed, but those 4W resistors makes me think of the dissipated heat. Overall, it’s great to have a 24V/10A power supply built with few components.

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