A dual power supply is a regular direct current power supply. It can provide a positive as well as a negative voltage and ensures a stable power supply to the device as well as helps to prevent system damage. As many electronic circuits require a source of DC power, the need for dual power supply for certain circuits is necessary. If you use any operational amplifier or some special IC means you need to give +ve, GND, and -ve supply. And sometimes we use the battery as a power source, so we cannot get these supplies. Here we design a simple circuit to avoid this problem.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | IC | NE555 Timer | 1 |
| 2. | IC | LM7909 | 1 |
| 3. | Resistor | 470Ω,100KΩ | 2, |
| 4. | Capacitor | 10nF,0.47uF,220uF/16V,1uF/16V | 1,4,2 |
| 5. | Diode | 1N4007 | 4 |
| 6. | ON/OFF Switch | – | 1 |
| 7. | Connecting Wires | – | – |
| 8. | Battery | 9V | 1 |
Circuit Diagram
Construction and Working
Here as we can see the main parts of the circuit are timer IC 555 and IC LM7909. Here IC 555 is used to oscillate pulse, we can rectify these pulses into -ve supply by using diodes, and regulation of negative voltage can be done through IC 79xx. The frequency of the square wave produced by IC 555 depends on the values of C1, R1, and R2. Here the frequency of the signal may slightly change with the temperature variation but the change in frequency does not affect the output voltage of the circuit. Capacitors C3, C4, C5, and C6 and diodes D1, D2, D3, and D4 form the Villard cascade voltage multiplier. The output voltage from the Villard cascade voltage multiplier is fed to the linear negative-voltage regulator IC2 to eliminate ripples and get an accurate -9V DC. Capacitors C7 and C8 provide additional noise filtering.
Now as the main power source battery gives a +ve 9 Volt supply, this is directly fed to the output connector with the help of R1, R2, and C1 timing components. Then the timer IC produces pulses at the output, this pulse is converted to a negative direction and regulated by the negative regulator IC7909. In the end, this negative voltage and GND supply are given at the output connector.
Applications
The dual-voltage power supply is required especially for powering the op-amps and some of the instrumentation amplifiers. A few low-power audio pre-amplifiers also use dual-voltage supply.
