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Thursday, 1 July 2010

how to Construct a two station Intercom

This intercom project provides the schematic and the parts list needed to construct a very simple wired two station Intercom. This project will help beginners to electronics understand one of the application of operational amplifers(OP AMP). In this case, the LM 386 operational amplifier is configured as an amplifier.

LM386 Low Voltage Audio Power Amplifier

The LM386 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.


a) Battery operation
b) Minimum external parts
c) Wide supply voltage range: 4V–12V or 5V–18V
d) Low quiescent current drain: 4mA
e) Voltage gains from 20 to 200
f) Ground referenced input
g) Self-centering output quiescent voltage
h) Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8W, PO = 125mW, f = 1kHz)
i) Available in 8 pin MSOP package


a) AM-FM radio amplifiers
b) Portable tape player amplifiers
c) Intercoms
d) TV sound systems
e) Line drivers
f) Ultrasonic drivers
g) Small servo drivers
h) Power converters

Those who are adventurous can also configure one of them to be permanently ON which means it can be used as a remote listening microphone by just a simple soldering of the 2 points of the circuit.

You can find the CK204 Two Station Intercom kit here under the SURVEILLANCE AND SECURITY (SPY) category.


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