50 W transistor amplifier
Description.
A very rugged and reasonably power amplifier circuit that can be used for any audio applications. The amplifier produces 60W rms at 50V supply on a 8 Ohm load.The circuit is designed such that most of the components are not critical and can be easily replaced by nearest values.This make it ideal to assemble from your electronics junk box.
The capacitor C1 controls low frequencies and capacitor C2 controls high frequencies.The circuit ia basically a class B amplifier.The transistors 2N 3055 serves the function of driving the speaker.The other transistor functions as pre amplifiers for the driver stage.This is the basic scheme of the circuit.The maximum power level of amplifier can be set by adjusting the 500 Ohm POT connected with the BC107 transistor.
Circuit diagram with Parts list.
Notes.
- The circuit can be powered using a 50 V DC power supply with 5A current rating.Up to 60 v can be given to the circuit.Any way the power supply must be well regulated and filters to avoid noise.
- Adjust the 500 ohm POT to obtain optimum performance.
- All capacitors must be rated higher than the supply voltage.
- Volume control can be attained by connecting a 10 K POT in series to the input of the amplifier.(Not shown in circuit).
Hi, Can you please tell me what each component is doing in the circuit?
Hi, I was trying to build the circuit for 50 W transistor amplifier on Multisim but I couldn’t find transistor BC286 and BC287. Can you please tell me what can I use instead of them? Are there any equivalent transistors? Thank you in advance.
you can use european components like BC177/557/157B for BC212, medium power BD137/BD139 can be used for BC286, BD138/BD140 can be used for BC287 which are quite rugged and reliable. please note these plastic medium power transistors have center lead collector left emitter and right base as you view the leads and metal heat sink portion viewing down. this is a very reliable amplifier. Please enjoy the sound with solid punch and power.
BC212 is for stailising half supply at positive end of spkr coupling capacitor. BC286 is driver, BC286/287 is a complimentry driver for output 2N3055. BC107 is the thermal compensation as well quisent current stabiliser for out put transistor 2N3055s (say around 50mA). The gain of the amplifier is governed by emitter resistance of BC212 2-3K and 20 to 100ohms resistance. you can adjust the ratio in such a way you maintain around a gain of 50, for better frequency response and distortion due to over loads. wish you happy listening.
HI
This chart uses pspice to simulate may ??
ok or no
And tells me All transistor’s function is??
And tells me the oscillogram the illustration
Thanks
Hi! I built this amp and it`s not working. I triple checked everything and it looks ok to me. But when I connect it to power nothing happens. I measured the standby current(current to the circuit when not loaded) and its very low (4.5mA). Power supply is 35V 5A. I measured all transistors with multimeter and they seem ok.
Does anyone have an idea what could be wrong?
Hi again. Problem solved. One of the BC transistors was fake. I replaced it and now amp is working fine and its fu**** loud!
Thanks for that circuit!
We’re having problems in out audio amplifier and we’re getting 10 – 50 volts DC output….
Reply to Ezekiel Fernandez
There is no problem with this circuit.I think you may have made some connections wrong. Also,you need to adjust the 500 ohm POT for optimum performance.This circuit is successfully tested by many guys.
Hi Mr fernabdez you should get 25 to 30 volt at out put transistor emitter resistance junction conection to speaker coupling capacitor positive terminal. if not there is something wrong in the wiring. This circuit is based on philips audio application book 1972. a stable reliable amplifier.
donot give up please find out the problem and solve it you will appreciate the results.
Thanks for the reply… i’ll try to seek out the problem…. anyway i think we had problems on the transistor replacements
can’t find a replaceable value for those nano farad capacitors
Hi Fernandez nano farad – 100nF is 0.1micro Farad. micro farad X 1000 is nano farad.