Not talking about you using the wrong transistors in the "altered ab amp":
1) Do you understand that its first transistor was biased wrong causing the top of the waveform to be severely clipped.
2) Do you understand that the resistor that turns on the NPN output transistor had such a high value that the output could not go above 5V even though the supply was 9V?
3) Do you understand that the output with bootstrapping goes higher than any resistor can do it by itself?
4) Do you understand that the emitter resistor on the first transistor reduces amplifier voltage gain so if the input signal level is not very high then the output level is very low and faint?
5) Do you understand that the signal source (phone or MP3 player) output impedance is part of the calculation of this very simple amplifier's voltage gain?

Then of course, do you understand that a power transistor has a low current gain so it needs a very high AC and DC base current compared to a little low current transistor that has a very high current gain when it is not overloaded?

Some of that I did understand and some I did not. However I was using 12 volts and my phones output is comparably high for most output capable devices. I did change resistors to lower values, that's what made it work to begin with. I can assure you I didn't use the diagram as shown. I changed around all of the cap and resistor values. Increased the voltage from 6,9,12, and even to 40 volts. Changing components each time. High and low values. I did get a very clear approximate 1-2 watt output. Again I'm using older components and their tolerances are greater than newer ones. Most don't even have tolerance bands so I'm assuming around +-20%? My goal is to make something using "old school" components and it sound as good as it did back then. I did find several different schematics that seem much more applicable to my components so I plan on trying them out. I believe the diagram I posted was meant entirely for proof of concept and not a truly useful version.

 

My primary ones are TIP41C/TIP42C. However I scrap nearly all of my components from old monitors, tvs, radios, computers and monitors, and essentially any device that doesn't use surface mount components. If it has through board pinouts, I salvage it. Transistors? Probably every commonly used one to exist. Seeing as I've never encountered a tip or a 2n2222 before so I'd say they aren't really common. Easy to buy yes but to salvage no. So many circuit's recommend using components I've never seen. Took me 3 hours to find 2 1ohm resistors earlier.

 

The sim program did not produce the expected smoke and didn't even give a warning when those weak low current transistors were very overloaded.
The sim program uses "typical" transistor spec's but it is a pain to change the spec's to minimum or maximum which is what you buy.
I don't think a sim program knows that a reverse-biased emitter-base junction has avalanche breakdown like a zener diode if it gets more than 5V to 8V.

That's probably what's going on with me. Diagrams are diagrams but it's impossible to be exactly sure what someone else us using is what it's supposed to. My TIPs are labeled but that doesn't mean s.h.i.t in the real world. My resistors or caps could have suffered degradation over the years. Who knows. So to me saying my components are likely at fault it's probably the case. Most are much older than me(30).

 

Sure I agree! The TS posted the original circuit, I was just curious if it would actually work.
SG

The altered on worked for me but only around 1 to 2 watts. Which I don't believe it's meant to do more. Just to be a proof of concept or a learning tool.

 

Transistors? Probably every commonly used one to exist.

So do you have any 2N3904 and 2N3906 transistors? Can you give us some specific numbers besides the TIPs.
SG

 

So do you have any 2N3904 and 2N3906 transistors? Can you give us some specific numbers besides the TIPs.
SG

I'll need to be home for that. But salvaged off top of my head i have c1815, a933. I guess common small signal transistors. Things commonly found in electronics. I have a few large pnp and npn but I don't think I'll be able to push those. Without using about 10 batteries.

 

I'll need to be home for that. But salvaged off top of my head i have c1815, a933. I guess common small signal transistors. Things commonly found in electronics. I have a few large pnp and npn but I don't think I'll be able to push those. Without using about 10 batteries.

Any that you recommend? If they aren't to crazy on pricing I'll buy them.

 

Any that you recommend? If they aren't to crazy on pricing I'll buy them.

The 2N3904 and 2N3906 will work, 19 cents apiece from Digikey. Select First Class Mail as your lowest cost shipping option.
SG

 

The 2N3904 and 2N3906 will work, 19 cents apiece from Digikey. Select First Class Mail as your lowest cost shipping option.
SG

Thank you much. I shall buy some!

 

When you get the parts try the circuit below. Breadboarded and verified.
SG

 

2N3904 and 2N3906 have a max allowed current of only 200mA and work poorly above 50mA.
2N4401 and 2N4403 have a max allowed current of 600mA work well below 200mA and cost the same as the weak ones.

When you buy transistors do you ask them to test thousands and give you only ones with "typical" spec's? They will laugh at you because some have maximum specs and others have minimum specs and you get whatever is there.
That is why you should design with minimum spec's so that every circuit you make works perfectly.

Here is my analysis of the last amplifier that was tested (transistor spec's unknown but probably not minimum):

 

When you get the parts try the circuit below. Breadboarded and verified.
SG
View attachment 158050

Thank you! That's what I've been needing this whole time! Something to use with what I got. I will build it. I found a large batch of 200. 50 of 2n3904 and 2n3906 with a lot of other types for around 12$. I still plan on using opamps but this will help me learn by giving me something to study the components and figure out the math in a way I understand.

 

I found a large batch of 200. 50 of 2n3904 and 2n3906 with a lot of other types for around 12$.

Be careful where you order from. If you are getting Chinese knockoffs it might not be such a good deal.
SG

 

Be careful where you order from. If you are getting Chinese knockoffs it might not be such a good deal.
SG

Can't guarantee that from anywhere. Seriously not much made in the USA anymore. But it is a USA company so there's a 50/50 chance they will be ok. The ics I planned on buying are USA made. Some may not work because they were scrapped but it's no different than buying knockoffs. I have 5 lm386 prebuilt pcbs that work great from china. Granted wayyy smaller than I expected, but that aside I think everything is a gamble when it comes to quality. Even my oscilloscope had about a 20% chance of working because it was from colleges(kids break shit) in the US. It does. I got lucky. Very few others got such luck.

 

(transistor spec's unknown but probably not minimum):

Exactly which is why the circuit works just fine.
SG

 

an't guarantee that from anywhere. Seriously not much made in the USA anymore

It's more about buying from reputable suppliers.
SG

 

It's more about buying from reputable suppliers.
SG

True. I generally read all the negative reviews to see exactly what problems were. Usually slow shipping or it didn't look like the pictures(different color) but if the reviews consistently say it didn't work then I don't buy no matter the rating.

 

2N3904 and 2N3906 have a max allowed current of only 200mA and work poorly above 50mA.
2N4401 and 2N4403 have a max allowed current of 600mA work well below 200mA and cost the same as the weak ones.

When you buy transistors do you ask them to test thousands and give you only ones with "typical" spec's? They will laugh at you because some have maximum specs and others have minimum specs and you get whatever is there.
That is why you should design with minimum spec's so that every circuit you make works perfectly.

Here is my analysis of the last amplifier that was tested (transistor spec's unknown but probably not minimum):

Thanks for the insight. I do generally question the quality of everything I have along with my salvaged parts. I try to be gentle removing but human error is fairly common. I have attempted to build circuit's using less than suggested voltages and only upping it to norm to double check. I'm fairly confident I'll get the hang of it soon. Unfortunately I don't have as much free time as I'd prefer. Definitely not giving up on this new hobby!

 

I was out of the loop for a while but now, seeing where this thread has wondered, why not just use one of the circuits that work that are found on RELIABLE websites? Certainly there is a whole lot of useless error filled stuff that will not work and can't be made to work, but there are other sites that everything they show works as promised as soon as it is wired according to their published circuit.
Unfortunately my computer with cad software and my technical files suffered lightning hit last Friday and so I am stuck on one laptop with only win7 and WP and FireFox. Sorry about that, folks.

 

I was out of the loop for a while but now, seeing where this thread has wondered, why not just use one of the circuits that work that are found on RELIABLE websites? Certainly there is a whole lot of useless error filled stuff that will not work and can't be made to work, but there are other sites that everything they show works as promised as soon as it is wired according to their published circuit.
Unfortunately my computer with cad software and my technical files suffered lightning hit last Friday and so I am stuck on one laptop with only win7 and WP and FireFox. Sorry about that, folks.

While I haven't given up on transistor amp circuits I decided to buy TDA2030/TDA2050's for a more direct approach for what I'm wanting. I've found many transistor circuit's I plan on trying but I haven't got to them yet. I did have an issue with the 2050 though. The TI schematic won't work for me. I changed nearly all the values of all the components then it did. Very well. But only through a 4ohm 10watt computer speaker. Confusing but I'm sure I'll figure it out.