10 Watt Power Amplifier

10 Watt Power Amplifier

16

Transistors: Tr1 BCY70 (or BC 182L or BC212L or BC214L) Tr2/3/4 BFY50/51 Tr5 BFX88 Tr6/7 2N3055

Risk of instability if no input connected. When testing, connect R (about 3k3). Needs well smoothed power supply of about 20 to 30 volts. Peak power is well over 10 Watts.

The table below shows the approximate voltages to be expected when using a 24v supply and with the variable resistor set to give a current of about 40mA in the output stage.

Test point Approximate voltage Tr1(e) 12·5 Tr1(c) 0·65 Tr2(c) 12·5 Tr3(c) 14·4 Tr4(e) 13·7 Tr5(e) 13·1 Tr5(c) 0·6 Tr7(c) 13·1

Circuit diagram : Component Side

Circuit diagram : Copper Side

Acknowledgements : The 10W amplifier is taken from "Transistor Audio and Radio Circuits" published by Mullard.