car amp?

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You may have hermano (brother), some amplifier made with transformers and darlington.

Those are cheap and work reasonable.
We have here a lot of factories doing that kind of schematic...using input transformer and another one to invert phase to output darlingtons.

Your industrie may have a lot of models this way, if not, may have imported from us, your neighboors.

Unfortunattelly i have not the schematic anymore...but the idea is simple.

Input transformer have around 8 ohms impedance, to receive audio from CD player or Radio tuner....this transformer secondary have a higher impedance and a center tap..... bias voltage enter this center tap and goes ,together with the audio, to the two PNP TIP140 transistors...this will invert phase to each TIP140 base, forcing them to make a complementary phase this secondary, the input transformer secondary is injected bias voltage, and this is produced with resistor in series with diodes producing the needed bias to make them conduct.

The output transformer in some amplifiers are only a single coil, feeding 13.8 volts in the center tap, the transformer will supply the transistors output with DC voltage.

Some amplifiers capture audio in this second transformer center tap, with an electrolitic condenser.....and others have a secondary coil in this output transformer.

Some of them, with darlingtons, are producing 70 RMS each those are the cheapest ones.


Silly question, but what are you actually looking for ?

I see a bunch of different questions, even a thread on smps's,if i were you i'd start with something easy without exotic parts.
Building an smps and making transformers for it isnt that difficult but you'd have to have a little knowledge of what you are exactly doing.
Try a search on diyaudio, you'll find more than one post on car amplifier and smps designs, some of them are mine.
well jacco, thanks for reply this post....

ill explain with a few words what what im looking for....

"im looking help to build/design an Car Amp" thats all :D

btw, i start learning electronics this year (in my house) i bought 2 books and i start making exercises.. i already learned how biasing transistors (i know that its just the beginner).... and i made a lot of exercises abt that... i never biasing an real transistor just in papers...

While i sleep or my mind is free i just start thinking abt problems that i will get when i will goto design the amp (i know that maybe i never will design an amp but i will try at least) so a lot of questiong come in mind... for example... wich transistor i need to use?!! so i started this topic.. and i already know that i will use
Sanken 2SC1216/2SC2922 output devices, Toshiba 2SA968/2SC2238 drivers :)

and last night i was thinking abt the volts of the battery so i asked abt it and i get the answer too, an SMPS.. :D

thanks to all of you guys, hope someday i can design my own amp and run it on my car.....

last night i was searching and reading a lot from diyaudio and i get a lot of useful info....

so im very happy...

i dont have the enought knowled right now, im studing how the ac signals works in the transistor...

sorry for my english and thanks Again to all of you...
Hi Samsagaz ! your mail.
I think Carlos is talking about the schematics in this thread.

I was quite amazed about that circuitry, and never tried it.
But last year, I came to the conclusion that it could work and
it seems to be one of the most simple and cheap designs.
I would rate it as LoFi, but if your requirements for sound quality
are not high, then it could be worth a trial.
Unfortuantely I do not have further detail information about this circuit,
also no hints to take care for :scratch1:

Good luck
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