Three transistor audio amplifier


Posted on Feb 5, 2014

This is the circuit diagram of a simple three transistor audio amplifier that can deliver around 100mW power to a 25 Ohm speaker. The diodes D1 and D2 provides a constant bias voltage for the transistors Q1 and Q2. The transistor Q1 works as a preamplifier. Transistors Q2 and Q3 drives the speaker. The type no of the transistor is not very crucial


Three transistor audio amplifier
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here. You can use any NPN transistor for Q1, Q3 and any PNP transistor for Q2. Any way the minimum collector current capacity of the transistors must not be less than 100mA. The circuit will work well with an 8 ohm speaker too, but the volume will be a little less. I have two question. (1) can 16v rated capacitor replace the C1, C2. Because you said c1, c2 must be rated 15V. Then, secondly can we connect a speaker to the input of this circuit to make it a microphone I have two question. (1) can 16v rated capacitor replace the C1, C2. Because you said c1, c2 must be rated 15V. Then, secondly can we connect a speaker to the input of this circuit to make it a microphone hi can i ask if how much capacity of an amplifier would i use in a 400W speaker and should i install a capacitor on my speaker how much capacity should i put on the speaker pls i need your advice tnx our assignment is to make a combinational circuit of BJT and FET. at first we are to submit an amplier circuit with three stages. and we pass the circuit above. Hi RKH you can use a 10K potentiometer for volume control connect C2 negative terminal to slider of the potentiometer. one end of the potentiometer to common (emitter of Q3. now connect the input to common and and other (free) end of the potentiometer. Hi Raj, No major change is required. keep the same circuit assemble and change R1 to 390 ohms and change the Q3 base bias reistance R2 100K to 100k preset...




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