The circuit given below shows a negative reference voltage supply.The reference voltage can be set to precise values by R2. The circuit operates in the same manner as the positive reference voltage supply circuit shown previously.The circuit is nothing but an inverting DC amplifier based on IC uA741.The circuit operates on a negative power supply and produces a negative reference voltage at the output.
Circuit diagram with Parts list.
- Assemble the circuit on a good qualtiy PCB or common board.
- Mount the IC on a holder.
- The POT R2 can be used for precisely setting the output voltage.
- The formula for determining the output voltage is ,Vout= -Vz [(R1+R2)(R1) ]; where Vz is the break down voltage of zener diode.