Posts Tagged ‘Pre-Amplifier’
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 …
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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 …
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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 …
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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 …
The basis of an audio mixer is an inverting summing circuit below. For real audio mixers, a single-supply voltage is seldom used.
To increase dynamic range, the designer will often push an op amp up to, and sometimes beyond it’s recommended voltage rails. Noninverting summing circuits are not recommended, but it’s possible to use. The source …
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Sometimes, in linear equipment design, it’s necessary to take a voltage which is referred to some dc level and generate an amplified output which is referred to ground. Using a differential amplifier similar to that shown in the circuit diagram below (the upper one) is the most straight-forward way of doing this. However, this circuit …
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