Negative Voltage from single positive power Supply


Posted on Feb 24, 2013

Opamps are very useful. But one of their major drawbacks is the requirement of a dual supply. This seriously limits their applications in fields where a dual supply is not affordable or not practicable. This circuit solves the problem to a certain extent. It provides a negative voltage from a single positive supply. This negative voltage together with the positive supply can be used to power the opamps and other circuits requiring a dual supply. The circuits operation can be explained as follows: The 555 IC is operating as an astable multivibrator with a frequency of about 1kHz. A square wave is obtained at the pin 3 of the IC .


Negative Voltage from single positive power Supply
Click here to download the full size of the above Circuit.

When the output is positive, the 22uF capacitor charges through the diode D1. When the output at pin 3 is ground, the 22uF discharges through the diode D2 and charges the 100uF capacitor is charged. The output is taken across the 100uF capacitor as shown in the figure. A disadvantage of this circuit is its poor voltage regulation and current limit. The max. current that can be drawn from this circuit is about 40mA. If you draw more current, the regulation will be lost. Also the output negative voltage will be a little less than the positive supply due to the diode drops. For example if the voltage is +9V then the output voltage will be about 7.5 V.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Multi Rocket Launcher
    Car rear Stop Light Flasher
    Digital Thermometer
    Centrifugal fish autofeeder
    Audio and amplifier circuits
    You Have Mail!
    650mA Micropower Low Noise Boost Converter with Output Disconnect
    Atmel At90S2313 Countermeasures



    Top