Hello,

If you want to know more about the germanium transistors, have a look at the following PDF:
http://www.tubebooks.org/Books/Krugman_transistors.pdf

This is one of the books from PMillet's site:
http://www.tubebooks.org/technical_books_online.htm

Bertus

 

thx alot guys i've did it, but it can't even drive a pair of headphones @5v, that low efficency of class A and these transistor.... well, an other thing to put away that works (kinda of), now i've build a cheaper amp, pure class B with an op amp and neagative feedback , it's working from the same battery (-+ 2.5v).
Maybe i'll start a new thread about it, just to see if it's possible to build a bigger one.

 

You have to ETO to AG

If you see that this has happened and AG responds, please post the link.

 

If you see that thus has happened and AG responds, please post the link.

what do you mean for ETO to AG?

 

You can ignore the previous posts with regards to AG and ETO. It is an in thing.

With regards to your one transistor class A amplifier you must be doing something wrong.
It is perfectly doable to drive ear buds.

Post your circuit diagram and we will set you straight.

 

Hello,

Audioguru was a member over here that knew a lot about audio circuits.
Read the following thread what happened to him:
just found out abt Audioguru

He is still active at ETO ( http://www.electro-tech-online.com/ ).

Bertus

 

i've deleted the scematic like an idiot, but here is the img where i've got it,
http://electronics.stackexchange.co...mmiter-amplifier-use-a-pnp-transistor-instead

is the second img colored black, the resistors are: RE and CE got removed, RL was 2k2, and the two other top to bottom were 4k7 and 1k.

btw i've build this amp and it works great, but what if i want to put more transistor and give in more power? how can i give (say 45 v+-) to that little LM358N ? here is the schematic

 

The simple class A amplifier you have shown will not work with headphones. The output impedance of the amplifier does not match the impedance of your headphones.

If you wanted a simple audio amplifier you could have used an LM386.

In future, you can benefit tremendously by coming here for advice first before embarking on an electronics project on your own.

 

The simple class A amplifier you have shown will not work with headphones. The output impedance of the amplifier does not match the impedance of your headphones.

If you wanted a simple audio amplifier you could have used an LM386.

In future, you can benefit tremendously by coming here for advice first before embarking on an electronics project on your own.

will it work with 8ohm headphone? (yes i have 8 ohm homemade headphones XP)

i've kinda putted aside the class A amp with those guys, i'm working on the "super class B amp 4 component in total" and i've asked how can i increase the power on it, by simply increasing the power supply and putting more power transistor, okay, but the lm358n will suffer that high voltage, and is ok on how i've wired everithing? beacause i have to short the jack to the ground before plugging, cuz sometimes it sounds bad, i have to "reset" it.

 

Scrap the idea of using the LM358 as a headphone amp. It is not designed to provide power. Use the LM386 like I suggested.

 

Scrap the idea of using the LM358 as a headphone amp. It is not designed to provide power. Use the LM386 like I suggested.

the lm358n is just a opamp with negative feedback that i had, it's driving 2 complementary class B transistor and is having a negative feedback so it corrects the 0.7 v thing of the transistors

 

the lm358n is just a opamp with negative feedback that i had, it's driving 2 complementary class B transistor and is having a negative feedback so it corrects the 0.7 v thing of the transistors

The LM358 is not powerful enough to drive the 32 ohm load of headphones. It is an op amp, you need an audio amp line the LM386. It is not a great amplifier because of the hiss but it will let you hear the germanium sound (which will have hiss of its own). It will not have a 0.7 v drop, germanium is only about 0.3 if I remember correctly.

The LM358 needs 600 to 1000 ohm load to operate well. If you add 560 ohms in series with your headphones, then you will hear almost nothing through your headphones.

 

OP wants to drive a power stage after the OPAMP.
Which is somewhat OK. It will be like a TDA2030
Even TDA2030 is easier to build

 

OP wants to drive a power stage after the OPAMP.
Which is somewhat OK. It will be like a TDA2030
Even TDA2030 is easier to build

yep, that's what i want to do, maybe doing a darlington pair with a PNP and the germanium PNP, and a skilai (kinda) pair with a NPN and the other PNP germanium? can this work?

 

Silicon NPN and a germ PNP. That's odd sorta pair.....!

 

i've made that class b amp using 3 transistor for each "side" of the class B push pull, one side is using bc548, 2sd718 and a TOSHIBA C5198 , the other side is using a bc558, 2sb688, and, guess what? that germanium guy , the amp is amazing powerfull, is driven by a 18v +- and, rly i was playing with the soldering iron which has the tic grounded and i've touched the negative feedback resistor and BAM, powerfull music (distorted),so i've hooked up a trimmer to the resitor to the ground and it's driving my speakers to the maximum!!! i would find a way to replace the toshiba with the other germanium tr. but pnp on a npn position??, the IC that i'm using is a 741cn, scrapped from an old board.

 

i've made that class b amp using 3 transistor for each "side" of the class B push pull, one side is using bc548, 2sd718 and a TOSHIBA C5198 , the other side is using a bc558, 2sb688,

BC548, 2SD718, 2SC5198, BC558, 2SB688....?
Which one is Germanium?
All I can get are Silicon Transistors.

that germanium guy ,

Now it's a Germanium Guy ?
I thought it was transistors....!

the amp is amazing powerfull, is driven by a 18v +-

±18V ..! Eh!
Do you know the maximum power obtainable to
4Ω is around 50W or so if the supply is strong enough and to 8Ω is around 20W...! This ain't bad though. If the Speakers are properly rated this will be loud . But there are single chis that can deliver more power than this. But in your case this might not be bad. And if that Amp is sonically good, sound will be quite good.
* Power rating are rough figures.

rly i was playing with the soldering iron which has the tic grounded and i've touched the negative feedback resistor and BAM, powerfull music (distorted)

You were soldering while the amp was powered. Are you nuts ?

so i've hooked up a trimmer to the resitor to the ground and it's driving my speakers to the maximum!!!

Huh !.

would find a way to replace the toshiba with the other germanium tr. but pnp on a npn position??, the IC that i'm using is a 741cn, scrapped from an old board.

This is something new. How can you replace any of the transistor u said above with Germanium ?????

What about the biasing voltages and gain and all tht???
Amps are operated with proper biasing. If you switch Silicon to germanium biasing will be wrong.

Why are you asking NPN or PNP ?
I don't think any one here will advice on replacing silicon with germanium.

Still hooked up on Old germanium's ? I don't get you..!

And why do you want to replace any OP AMP with an obsolete, terrible sounding 741 ? Get a good OPAMP like TL072's or TL082's. They are far better for audio use.

 

Did it! pure class B germanium amplifier!!!! i'm going to put some pictures


Damn this transitors are like dogs that bite his tail, they heat up, and by heating up the IC keeps correcting them until it starts to make a hum, and they almost burn, have to place a good heatsink and 2 resistors between the collector of the first and the emitter of the second, i have some of them 0.5 Ohm. Everythingis powered by a 60 VA toroidal transformer, the output was 35-40 watt with the silicon NPN and PNP toshiba, and something around 15-20w with the germanium (and more heat!), and the DO the annoying lovely noise, but i'll switch back to silicon and build a stereo vesion and close everything in a case and have a 60 Watt amp totally homemade, even the toroidal, hand wounded

 

Wait...! You were playing with it and you accidentally touched one resistor and the sound increased so you put a trimmer there.

This gonna be fun..!
How long have you played the amp with high level sound ?

I wonder whether it will last. Or how the distortion figures are.

Hmmmm! I want to see what OP has done with my own eyes.
But I don't think I ever will.

 

You must be a legend..

Show us the works mate.