Voltage controlled amplifier LM324

A voltage controlled amplifier is an amplifier that can change its degree of amplification by a DC voltage. It is often called as "VCA". Look at the schematic for this project.

U1:A is an oscillator that generates the AC signal we use in this project. It gives out a high-pitched '"beep."

Q1 and Q2 work as a differential amplifier that changes the degree of amplification by a DC voltage set by the control volume and Q3 - Q5.

U1:B causes a sound in the earphone using the controlled output signal.

When you finish wiring the project, turn power ON and rotate the control volume. The volume of the sound you hear through the earphone changes as you turn the control volume.

Bill Of Materials For Voltage controlled amplifier
24 Resistors
Quantity: References Value
6 R1, R2, R5, R8, R19, R22 10k
3 R3, R4, R24 47k
2 R6, R12 22k
1 R7 150k
1 R9 33k
3 R10, R15, R16 1k
4 R11, R20, R21, R23 100k
4 R13, R14, R17, R18 4K7
7 Capacitors
Quantity: References Value
2 C1, C6 1uF
2 C2, C3 0.01uF
3 C4, C5, C7 0.1uF
1 Integrated Circuits
Quantity: References Value
1 U1 LM324
5 Transistors
Quantity: References Value
4 Q1-Q3, Q5 2SC945
1 Q4 2N5401
1 Diodes
Quantity: References Value
1 D1 1N4148
4 Miscellaneous
Quantity: References Value
1 + 9V
1 RV1 50k








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