A simple stereo amplifier based on C3856

Thread Starter

tcdk

Joined Jan 7, 2009
23
Hi

I would like to build a simple stereo amplifier with only input/output, volume and on/off @ 2x50-80w (at least)

I have some C3856 and A1492 laying around that I thought I could use for the project.

I've searched through google after a schematic using C3856 (or similair) but haven't found anything yet.

Does anyone have a schematic or something that I could use?

Thanks
 

beenthere

Joined Apr 20, 2004
15,808
If that's a 2SC3586, it's not gonna be easy. The transistor is rated for UHF and microwave amplification. Audio amplification would be an unusual application.

You can always try it as a substitute for another type in an existing design.
 

Thread Starter

tcdk

Joined Jan 7, 2009
23
If that's a 2SC3586, it's not gonna be easy. The transistor is rated for UHF and microwave amplification. Audio amplification would be an unusual application.

You can always try it as a substitute for another type in an existing design.
It's a C3586. I got it from a Akai stereo amplifier that died.
 

beenthere

Joined Apr 20, 2004
15,808
The number C3586 turns up things like furniture. It may be a non-standard transistor, and so will be impossible to get specifications.
 

beenthere

Joined Apr 20, 2004
15,808
Ok, the 2SC2856 is an NPN transistor good for 150 watts, 200 volts, and 15 amps - the 2SA1492's are the PNP compliments. They will sub nicely for any design with 2N3055's and 2N2955's.

There's a grunch here - http://www.hobbyprojects.com/A/audio.html - to choose from. If one is by Mike Leach, it is very good.
 

Thread Starter

tcdk

Joined Jan 7, 2009
23
Thanks!

I can't find any with the specific transistor, but found this one very interesting and easy.
http://sound.westhost.com/project19.htm

The LM3876 chip is also pretty cheap :)

Eg. @ futurlec.com the LM3876T is statet as "40W High Perf. Audio Amplifier"
and other places as 56W - should I make any differents in the layout if or is it the same?

 

Thread Starter

tcdk

Joined Jan 7, 2009
23
What kind of transformer would you use for a amplifier like that? (35V)
I found Hammond 266K35, but don't know if that will do.

And where should I buy parts? I normaly buy from futurlec.com, maplin.co.uk and mouser.com - but no one have both the LM3876 and a transformer that suits....
 

beenthere

Joined Apr 20, 2004
15,808
Transformers are quite expensive - can you get to some sites that offer surplus items? Don't forget you need the current as well as the voltage. A 24 volt transformer will give close to 35 volts DC after rectification with good filter caps.

You can always refigure resistor values if you go significantly up in voltage - say, 42 volts instead of 35. Your output transistors will handle the power, so see what transformers you can scrounge up and work with it/them.
 

Thread Starter

tcdk

Joined Jan 7, 2009
23
I just found out that I had a 40V transformer from a old amp.
I altso has a several ~36V outlets to :)

There was also a pretty large heatsink, some RCA chassis jacks, speakerouts and more.
Yummy!
 
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