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How to Use an IC 7812

The integrated circuit 7812 is a voltage regulator circuit that often makes up a portion of a power supply. A direct current power supply converts alternating current to direct current. After initial rectification, the direct current is filtered to reduce noise and smooth the current so it does not fluctuate. A voltage regulator prevents the voltage from exceeding the regulator's rated output. The LM7812 is a 12-volt, positive-voltage regulator, which means the output is held at a maximum of 12 volts.

Things You'll Need

6-volt batteries or DC power supply, 3
Jumper wires with alligator clips
22-gauge project board jumper wires
Project breadboard
0.33 microfarad, 35 volt capacitor
0.1 microfarad, 35 volt capacitor
Multimeter

Instructions

Regulator Circuit
- 1
  Clip an alligator clip on the positive terminal of battery A and the other end of the jumper wire to the negative terminal of battery B. Connect the positive terminal of battery B to the negative terminal of battery C. Connect the positive terminal of battery C to a 22-gauge jumper wire. Connect the negative terminal of battery A to a different 22-gauge jumper wire. The voltage between the 22-gauge wires is 18 volts.
- 2
  Lay the project breadboard on a table. Insert the leads of the LM7812 voltage regulator into three different vertical hole groups on the project breadboard with the numbering on the front of the regulator facing you. The leads on the voltage regulator from left to right are the input, the ground and the output.
- 3
  Insert a jumper wire in the top row on the breadboard and into the same vertical hole group as the input lead on the voltage regulator. Insert one lead of the .33 microfarad capacitor into the top row of the breadboard and the other lead into the bottom row of the breadboard.
- 4
  Insert the jumper wire into the same vertical hole group on the breadboard as the LM7812 ground lead (middle lead) and the other end into the bottom row on the breadboard. Insert one lead of the 0.1 microfarad capacitor into the same vertical hole group as the LM7812 output lead (right lead) and the other lead into the bottom row of the breadboard.
- 5
  Insert one end of a jumper wire into the output lead vertical group. Insert a second jumper wire into the bottom row of the breadboard. These leads are for testing the circuit.
Regulator Circuit Testing
- 6
  Turn the multimeter on and set it to test voltage in the range of 0 to 50 volts. Connect the red test lead to the positive terminal of battery C and the black test lead to the negative terminal of battery A. The meter will read 18 volts.
- 7
  Disconnect the meter from the batteries. Insert the lead connected to the positive terminal of battery C into the top row on the project breadboard. Insert the lead connected to the negative terminal on battery A into the bottom row on the breadboard. The circuit is turned on and operating.
- 8
  Clip the red lead from the multimeter to the jumper wire on the output lead of the regulator. Connect the black lead to the jumper wire on the bottom row of the breadboard. The multimeter will read 12 volts. The regulator is operating correctly.

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