When the electronics project is builded for dual power supply voltage, But you have only a single power supply source like Battery or a DC adapter. The single power supply can be converted into a dual power supply. To do conversion, the DC single power supply to dual power supply circuit is needed. Let’s build one.
Introduction
The circuit will work best with the DC adapter with 12V DC supply or more. THe lower voltage can work but if you provide lower voltage the output voltage will be half the input DC voltage. For a 12V DC power supply the output voltage is about +/- 6V DC. Providing higher voltage is better to work the circuit.
There are two versions of this circuit, the first circuit will provide identical voltages as in the two output terminals. The second circuit with the transistor has different power will get at each end of it.
If your external power supply is switched mode one then the possibility is high that the noise will generate at the output section. The first circuit is very simple.
1. Single power supply to Dual power supply using Voltage divider
It uses a Voltage divider on the input DC supply to make virtual ground. The circuit is made of a few electronics components, two resistors and two capacitors. The circuit gives two separate and well isolated power supplies to run the dual power supply boards.
You can use bigger capacitors to reduce the humming sound, use 1000uf capacitors in this circuit. The op amp circuit is able to isolate a lot of the noise issues.
Circuit
2. Dual op-amp Buffered Supply
The current from the voltage divider circuit is unequal so we need to go through this op amp based power supply circuit to get equal current from the supply.
Using a cheap op amp ic like UA741 to do this circuit. The circuit will give a well balanced output voltage.
The 10 ohms resistor provides the proper load and maintains the same voltage at the output. You can use a 4007 diode to protect the IC from the reverse voltage and you can also use a Schottky diode in this circuit to protect.
Circuit
3. Transistor based single to Dual power Supply
The transistor based circuit is able to handle more current, if you want to run an amplifier from a single power supply you can use this transistor based single supply to dual power supply converter circuit. Provide 24v dc to get 12v DC dual power supply with maximum of 3 ampere output.
Circuit
BD139 and BD140 transistor can provide the offset current up-to 50mA. If you want to get more current from the circuit you need to use TIP35 and TIP36 power transistors.
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