The circuit given below is a variable positive voltage reference supply.The reference voltage can be set to precise values by R2.Basically the circuit is a DC amplifier based on op-amp uA 741.The negative feedback is given via the zener diode.

Circuit diagram with Parts list.



  • Assemble the circuit on a good quality PCb or common board.
  • Mount the IC1 on a holder.
  • The POT R2 can be used for adjusting the output voltage.
  • The formula for determining the output voltage is Vout= Vz [(R1+R2)(R1) ]; where Vz is the zener voltage.

1 Comment

  1. Sir, If i need on board ground (can handle up to 100mA) what can I do (ie, What are the options) when there is dual polarity supply.