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How to Make a Voltage Amplifier

An operational amplifier, or op amp. contains most of the working parts for a voltage amplifier in an integrated circuit (IC) package. In addition to the op amp, the amplifier circuit needs only a pair of external resistors and a power source. It has a gain factor of approximately 10, so it produces five volts from a 0.5-volt input. You can assemble the voltage amplifier in 15 minutes.

Things You'll Need

Solderless breadboard
LM358 op amp
82K-ohm 1/4-watt resistor
10K-ohm 1/4-watt resistor
9-volt battery clip
4 12-inch pieces of 22-gauge wire
Tape labels
Pen
9-volt battery

Instructions

- 1
  Insert the LM358 op into the breadboard so its pin rows fit over the horizontal IC channel in the board's center. Use moderate force and make sure the pins go in straight.
- 2
  Set the 82K-ohm resistor into the board so one of its leads connects to pin one on the op and the other lead connects to pin two.
- 3
  Connect the 10K-ohm resistor to pins two and fouor on the op amp.
- 4
  Insert the battery clip's red wire to the op amp's pin eight. Insert the black battery clip to pin four.
- 5
  Insert one end of a 12-inch wire so it connects to pin three. Connect a second wire to pin one. Connect two wires to the op amp's pin four.
- 6
  Twist the wire at pin three and one of the wires at pin four together a few times. Write "Input" on a label and wrap the label on these two wires. Twist the wire at pin one and the remaining wire at pin four together. Label the two wires "Output." Connect the "Input" wires to a signal source of under one volt. Connect the "Output" wires to an oscilloscope, multimeter or other means of monitoring the signal from the amplifier.

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