simple dual rail supply for opamp using general purpose opamp and transistor

Take the blue net as gnd and the VCC and Real GND as + and - respectively. The blue net shows as 2.85v but once loaded with atleast a few uAmps it will come down to 2v. This circuit will split the main supply to dual rail half voltage supplies. The current source sink capacity (before the virtual ground pin starts getting loaded) depends on the type of pass transistor used for example with a transistor like BC547/8 it can easily deliver 50 to 60mA mostly enough for breadboard level playing around with dual rail supplies required for OPamp. Any general purpose opamp like LM358 can be used. Here the Opamp VCC/GND terminals are not visible but they are to be connected to main supply from which you are taking. However you can't get below +-1V so anyhow that is generally much necessary for small analog experiments. But the most important thing is that make sure there is no direct link between two devices connected to same power supply(i.e. they have common ground return paths like the source and your circuit which is to be powered using this supply have a common wall socket adapter etc) Just to be sure make sure the main source is battery for better performance and safety.

published 10 years ago