Free Simple Circuit Diagram
Dynamic microphone uses a moving coil around magnetic field to convert mechanical movement into electrical signal. The ordinary mini speaker is turned into a very sensitive microphone. Although it looks like misusing the speaker as a microphone, but actually a real standard dynamic microphone uses the same principle as this speaker. We can use any NPN transistors such as BC […]
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Circuit below is a very sensitive 3-transistor amplifier using a speaker transformer. This can be wound on a short length of ferrite rod as show above or 150 turns on a 10mH choke. The biasing of the middle transistor is set for 3 V supply. During idle conditions and the quiescent current is just 5mA, the second and third transistors […]
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This is a summing amplifier circuit. This is an inverting circuit that provides an inverted output equal to the sum of all three input. This circuit has some advantages such as there is no interaction between the operation and inputs, and also it is very easily to implement the weighted averaging and summing on this circuit. Here is the circuit: […]
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Not only a summing circuits, but there are also subtracting circuits. Here’s the circuit diagram: Subtracting circuit is a common application which is used to eliminate the vocal track (recorded at equal levels in both channels) from stereo recordings. R1 = R3 and R2 = R4, Vout = (R2/R1)(Vin2 – Vin1) R1||R2 = R3||R4 for minimum error due to input […]
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