Ampli2n3055

229

05:05:58

Simple power amplifier 2N3055 style popular in the 70's. Many similar designs on the web.
70W in 8 ohms with a 60V single supply. Sensitivity 800mV.
T1: NPN : BC547C
T2: PNP : BC557C
T3 : NPN : BD139
T4 : PNP : BD140
T5 and T6 : 2N3055 (or  better with 2SC5200)
Diodes : 1N4007 on the same radiator with T5 & T6.

Adjust the 30 ohms resistor (100 ohms adjustable should be used) for a quiescent current of 40mA in the 0.2 ohm resistor with shorted  input).

published 5 years ago

gasboss775

5 years ago

Ah yes, I remember these circuits well

gasboss775

5 years ago

I reckon you could improve this considerably by substituting the 2n3055's with a pair of 2sc5200, these are good NPN transistors designed for audio output stages. This would potentially permit higher power rail voltage but some of the resistor values might need tweeked also use a bigger heatsink for the 2sc5200's.

chutrinh

5 years ago

Can you send me the detailed calculation documents? sannolepro113@gmail.com

schmitt

5 years ago

gasboss775 : you are right : 2SC5200 from Toshiba should be better though 2N3055 has proven to be OK. The intrinsic bandpass should then be broadened resulting in a lower intermodulation distorsion. The other great advantage is their TO3P plastic case easier to work with the heatsink. I have not stated that a single supply with an output capacitor is simpler, avoiding a supply and DC output monitoring. Surely not the high-end design, good enough, simple

schmitt

5 years ago

Chutrinh : no I have not the dtailed calculation, but it is a well known design (you can find audio frequency power amplifier design analysis in the excellent books from Douglas Self or Peter Baxandall which were very active in these years). But you also may uses this app to inspect the voltages and currents.

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