How to Use 7809 Voltage Regulator?

Hello Friend,

Today, I will guide you through creating a voltage control circuit. With this circuit, we can transform up to 35V DC into a stable 9V DC using only a 7809 Voltage Regulator.

Let's begin,

Components needed:

1. Voltage regulator - 7809 x1
2. Capacitor - 63V 470uF x1 {I'm using a 25V 470uF capacitor as I'm providing a 17V DC Input.}
3. Capacitor - 16V/25V/63V 100uF x1
4. Input Power Supply voltage in DC - Input voltage < 35V {Input Voltage should be less than 35V DC}
5. Connecting wires
6. Clippers

This image illustrates the pins of the voltage regulator.

• Pin-1 is Input,
• Pin-2 is GND (Ground), and
• Pin-3 is Output.

Solder the +ve pin of the 470uF electrolytic capacitor to the Input pin/Pin-1 of the voltage regulator and

Solder the -ve pin of the capacitor to the GND Pin of the Voltage regulator, as shown in the picture.

NOTE: The capacitor voltage should be greater than the Input voltage. So, connect a 63V 470uF capacitor in parallel with the input power supply, as I connected in the picture. However, I'm using a 25V 470uF capacitor here because I'm providing a 17V input, which is less than the capacitor's voltage.

Next, solder the +ve pin of the 100uF electrolytic capacitor to the Output pin of the voltage regulator and

Solder the -ve pin of the capacitor to the GND Pin of the voltage regulator, as shown in the picture.

Now, connect clip wires to obtain a constant 9V DC output from this circuit.

Solder the +ve output wire to the Output pin of the voltage regulator and

Solder the -ve output wire to the GND Pin of the Voltage regulator, as shown in the picture.

Now that our circuit is ready, connect the input power supply wire to this circuit.

Connect the +ve clip of the Input voltage to the +ve pin of the 470uF capacitor and

Connect the -ve clip to the GND Pin of the voltage regulator.

NOTE: We can provide an Input Power supply voltage up to 35V DC to this circuit.

Now, as depicted in the above pictures:

• Picture-1) - I provided a 17.6V DC Input, and we obtained a constant 9V Output from this circuit, as seen in picture-2.

NOTE 1: If we increase the input voltage, the output voltage will remain the same, i.e., 9V DC.

This is how we can create a circuit to obtain a constant 9V Power supply using a 7809 Voltage regulator.

NOTE 2: Add a heatsink if the 7809 Voltage regulator gets heated.