7805 5V 1A Regulated Power Supply with Overvoltage Protection Circuit

lm7805 5V Regulated Power Supply Overvoltage overcurrent Protection Circuit

7805 5V 1 Amp Regulated Power Supply with Overvoltage Protection Circuit

This is the 7805 5 volts 1 ampere Regulator with Overvoltage Protection Circuit. Most of the COMS, microcontrollers and TTL ICs require a well regulated power supply. these ICs can easily damage when supply voltage is increased. basically this circuit provides overvoltage protection but it has over current, reverse polarity, and the regulator IC protection. So you don’t need to worry about power supply.

 lm7805 5V Regulated Power Supply Overvoltage Protection overcurrent Circuit diagram

R1 330Ω ¼W
R2 33Ω ¼W
R3 220Ω ¼W
C1 100µF 50V
C2 0.1µF
C3 10µF 16V
C4 0.01µF
C5 0.1µF
D1 1N4001
D2 1N4001
D3 6.2V Zener Diode ¼W
IC1 7805 regulator IC
SCR1 2P4M OR Similar 2A SCR

Our circuit design using 5V regulator IC, SCR and ZENER diode. Actually this is a crowbar circuit. It is an electrical circuit used to prevent an overvoltage condition of a power supply unit from damaging the circuits attached to the power supply. If the voltage regulator (7805) is faulty, the supply voltage could be applied to the load and it will damage our sensitive circuits. So we need this type of protection circuit. 

2P4M 2P5M 2P6M P-gate SCR PIN configuration Pinout

2P4M PIN configuration


When the output voltage exceeds 6.2V, Zener diode conducts. That voltage will switch on SCR, so this provides a short circuit to ground and fuse will be blown. The C1 capacitor is present to ensure that short spikes to not trigger the SCR. Also you can change the protection level by varying the values of D3 and R1. The D1 provides reverse bias protection and D2 provides output polarity reversal protection to the regulator IC.

If you get more than 400mA current, please use this regulator IC with suitable heat sink.


5V Overvoltage Protection Circuit 7805 Protection Circuit lm7805 1A voltage regulator protection lm7805 5V Regulated Power Supply Overvoltage Protection overcurrent Circuit diagram

Please send your ideas, which are very important for our success…

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22 comments on “7805 5V 1A Regulated Power Supply with Overvoltage Protection Circuit
  1. Asiri says:

    nice thing

  2. nathanael says:

    I give thanks to you for the posts you send to me

  3. Very good design .Thank u for post.

  4. mk says:

    good ideaer but how to now V of ZD 6.2V

    whats is mark ?

  5. Abdul Haque says:


  6. lintingan says:

    how if add indicator full and auto cut off?

  7. owoeye says:

    its a nice circuit, i use it to charge my phone but it was very slow. Please how can i increase the current? Pls i need help.

  8. soni says:

    what is max output current and voltage of your circuit..??
    what if we apply exactly 9v battery???

  9. hossin says:

    I am iranian .very to enjoy of site you .successful

  10. sena says:

    Very good design .Thank u for post.can you send new high Ampere power supply circuit diagram

    • Joseph says:

      use pass transistors to increase current. for example TIP2055 which delivers around 4amps. By using 4 in parallel you get 5V 16Amps stable.

  11. FRASER says:

    this circuit only for 1A, and how about 2A… thx….


    thanks that good

  13. Meek-Henry says:

    please sir, can you explain to me the operation of the various components

  14. Suleman says:

    pls sir, which component should i use instead of scr

  15. I maked a 5 volt mobile charger bt the circuit is not working properly. My mobile charge is going down when connect the charger. Plz Help me..

  16. Alberto says:

    What thyristor is needed for 12v 2A.

  17. AnFo says:

    By the look of it, if there is a voltage high enough over the zener diode D3, the thyristor will conduct and you’ll have a short circuit across the supply!!?? You’ll need to add a current limiting resistor inline with the thyristor

  18. Sithum says:

    Is this circuit secure for mobile phone charging?

  19. This IS a NICE design!!!!!!!!!!!

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