i'm going to, i'll try to put a video, but pictures are incoming :3

22 mb of RAW pictures of a 24 megapixels camera 8D

the biasing and everything is done by the negative feedback, the opamp is driving 3 transistors in darlington like a boss, distorction is pretty good, there is some at pretty low levels, in the mid is perfect and then getting over the max power, the 741 was one of the chip that i could find :3 i've tested the lm358, the 741, and i've found a lm386 but i don't know if it works

 

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

But I was right about the power ratings, huh !
Germanium are not good for Audio power stage as far as I have seen.

So you are giving up on Germanium ?
That's a relief.

 

i'm going to, i'll try to put a video, but pictures are incoming :3

22 mb of RAW pictures of a 24 megapixels camera 8D

the biasing and everything is done by the negative feedback, the opamp is driving 3 transistors in darlington like a boss, distorction is pretty good, there is some at pretty low levels, in the mid is perfect and then getting over the max power, the 741 was one of the chip that i could find :3 i've tested the lm358, the 741, and i've found a lm386 but i don't know if it works

U need to change the picture to jpg's

If you are building one then build a better one.
There are far better ones here than you currently have.
If you can built what you have, then you can do better.

I have build Rod's amps and are the best I did so far.

 

kinda of but ho well, i've did it i'm going, as i said, to build a stereo version with silion ones , at least i've tried all by myself and by your help , and did i said that i'm 15 ? and italian as you can see my english sucks a bit hehehe

 

You are 15 ?
Not bad for a kid then.

Your English is better than the Indian ones that come here. At least you say things more clearly than like,

wht da heck is trz?

You need to Read THIS. It will open your mind to new possibilities.

 

here it is, one of 2 imgs

hahahah what the heck is a transistor ahahahahah

i found nice the link that you sent me , btw i'm switching both tr. to silicon ones, i hate to say that but, silicon is better ;')

btw, just a question, there is a transistor without that thing (i think it's called Vbe) the 0.7 v problem?

 

Blimey. !
What the heck is that ?
Just kidding....!

You laid it like tht. Still not bad I admit.

The 0.7V thing is the biasing. Proper biasing will minimize distortion and produce Quality Audio.

Please read that site. You will learn a lot about biasing, distortion and types of Amps , the pro's and con's.

Good luck with that amp by the way, you already are a Legend.

 

Blimey. !
What the heck is that ?
Just kidding....!

You laid it like tht. Still not bad I admit.

The 0.7V thing is the biasing. Proper biasing will minimize distortion and produce Quality Audio.

Please read that site. You will learn a lot about biasing, distortion and types of Amps , the pro's and con's.

Good luck with that amp by the way, you already are a Legend.

Yeah, the biasing is something that i hate, infact i've used an IC with the feedback so it does that job heheeh, CRY&PRAY the Legend ehhehehe

 

Biasing has nothing to do with feed back mate. ( well, almost )

Biasing helps to keep the output stage in linear region. Which helps to reduce cross over distortion.
Feed back sets the dynamic range and gain of the amp to keep it stable under different loads and signal levels

 

Blimey! We don't prototype circuits like that anymore, or never did, unless we were looking for 10GΩ isolation.

Get yourself some perf board for prototyping unless you don't mind replacing blown semiconductors every time there is a short circuit.

 

Chips, don't rush him.

He is a legend like me.
I started the same way u know

Wait ! I was worse. I remember using super glue to stick wires to solder pads. Never understood why the darn things did not work then.
I was like in 7th grade or so.

 

Biasing has nothing to do with feed back mate. ( well, almost )

Biasing helps to keep the output stage in linear region. Which helps to reduce cross over distortion.
Feed back sets the dynamic range and gain of the amp to keep it stable under different loads and signal levels

yeah, i know, but the amplifier is done this way: the IC, drives the transistors and it receives on the negative pin in the input the output of the transistors, so if you see the output of the IC you get something that corrects the non linearity of the transistors, it uses the feedback to "listen" when the trs. are not working, and corrects that, if you see the amp has only 9 components, 6 transistors, the IC, the feedback resistor and the pot. to set the right grounding on the same feedback. The IC does all the job no diodes or else to bias

 

You have the right idea in principle. In practice you should begin with a circuit diagram.
Biasing a class AB, B or any linear circuit for that matter, is not kid's play.
I suggest you start with a circuit diagram and work with a simulator.
You will immediately be able to see the cross-over distortion on the simulator when the transistors are not biased properly.

 

That's what i did, ltspice this amp every time i've changed something, but i don't have any perf board to work on, and i kinda like the aerial style, i'll take some cooper tube and build a cool style clean aerial amp and close it in a clear glass box. i know what crossover distortion is, and the IC with the feedback came to correct this non linearity form a class B amp without using diodes and make it simple, it's not the best, but everyone can build one, and IT SCALABLE, just increasing the power supply protecting the IC.

 

here are the 2 schematics, one was for the Germanium PNP, one is for silion pair.

R4, in both schematics is needed to stabilize the IC, that when the jack is unplugged makes a strong hum and pushes the speaker inside.

the big IC to the left it theorical, is needed only when you give the amp more power and the IC is not rated, so you have to reduce the voltage, a few resistor will work, but it was easier for me to do that in LTspice.

forgot to tell, there are 2 more transistors in both schematics, as a triple darlington pair, not the normal one seen in the schematics. The IC correct 2.1 V *2=4.2V of dead zone!! and works pretty well!.

 

I've build everything using a metal wire, it's beautiful

 

You mean when everything is lying on the table.

 

nope, i've put everything in air i'll try to send a picture

 

Caramba !

That is what we call DIY amp kit.

I got to hand it over to ya, Kid.

You did the unthinkable.

Keep it up.

PS...There no way the tracks can be too thin. Eh!

 

Caramba !

That is what we call DIY amp kit.

I got to hand it over to ya, Kid.

You did the unthinkable.

Keep it up.

PS...There no way the tracks can be too thin. Eh!

This thing handles a lot of epicness in those "thin" wires , i've added a resistor between the output and the bases of the first transistors, to give a second feedback that reduced that bit of hum and distorction at low levels, i'll post the final schematic here. It can handle as much current you want, just make sure your transistors are rated for, and the IC is protected if you go over the +-18v in this case is the max for the LM358N, i found that using a 741 was giving me a DC ofset of 6 v!!! when i was giving the negative feedback to the IC. as far as i know then LM358N is pretty good, there are better for sure.

If the power transistors gets too hot put a 0.5 Ohm 5W resistors on both emitters