Bored...2n3055e amp?

[ThSpeakerDude88]

Hey I'm a little bored and got two of these lieing around, a couple of 4558's and 741's too. Would like to know if theres a simple amp I could build out of them.


Doesn't need to be powerful, a watt or more would be nice

 

[Netlist]

Have a look at Rod Elliott's site.
You will find many simple projects to make good use of these parts.

/Hugo

 

[ThSpeakerDude88]

alright, well I was hoping for something that ony used one transistor and an opamp, I could use a voltage regulator for bias. Any curcuits that could use this?

 

[jaycee]

If you have two 2n3055's then you could build something with a quasi-complementary output. You would need two medium power transistors such as MJE340/350 as drivers though.

 

[darkfenriz]

Any curcuits that could use this?

White noise generator.

 

[ThSpeakerDude88]

hah nice... I kinda meant amplifier circuits though

 

[darkfenriz]

These parts are obsolete and it may turn out to be waste of time to build up something from these. For also very low price you will get tl07x or NE5532 op-amps, which are way better. Modern power trasistors will be probably something like 2$.
No need to use your old dirt whereas silicon costs nothing nowadays, main expense is transformer, heatsink and PCB.

 

[forr]

Try something original. What about this one, dating from 1973 and due to P.L. Taylor ?

 

[davidallancole]

Is this more what you are looking for? You could replace the darlingtons with what you have for transistors. It won't produce much power, but you said you wern't looking for much in the first place.

 

[ThSpeakerDude88]

nice, I think that will work. If I set it up in multisim and test it will it give me close to accurate results? By the way... multisim looks very close to p-spice.. I downlaoded p-spice one time but I couldn't get it to work.

what voltage do the diodes need to be ( or are they not zeners?)

 

[ThSpeakerDude88]

umm... by the way.. I assume the output is bwteen the emitter on the top one and collector on the bottom, coupled with a 2200 uf cap or so , and to ground?

 

[davidallancole]

Yes, the output is from the top transistors emitter/bottom transistors collector. An output capacitor is not required. The reason is that it has a plus/minus supply and the op-amp compensates through the feedback loop to keep the output the same as the input. When the input is 0 volts, the output is 0 volts with respect to ground. So the top transistors Vce will be 15, as well as the bottom transistors when the input is 0 volts. The output from the op-amp will have a dc offset of 2Vbe or ~1.2-1.4 volts. The dc offset of the power amp over all will be 0 volts.

 

[davidallancole]

Oh. This works fine in the simulator. It takes a 1V input and turns it into a 13V output. When I built it in the shop, I added a 10 ohm resistor and 100nF capacitor in series from the output to ground and a 100pF capacitor from the output of the op-amp to the inverting input of the op-amp. This kept it from oscillating at all. It sounded very good. I used Tip 125 darlingtons and LM741. It still sounded good with this stuff. The cymbals sounded like ****, but I had 180pF from the output of the op-amp to the inverting input, which limited the high-end response. I didn't have anything else. The bass sounded very good though. Better then my 50W/channel amp that I had built out of LM12CL power op-amps.

 

[latala]

build a texan
this was a very simple amplifier that used a 741/748 opamp and 2 small npn bc212 1 x pnp bc212 a tp32 and a tp 32
results were very good about 15-20 watts many thousands were made i will try to get a schematic on when i get my scanner to work

 

[edl]

build a texan
this was a very simple amplifier that used a 741/748 opamp and 2 small npn bc212 1 x pnp bc212 a tp32 and a tp 32
results were very good about 15-20 watts many thousands were made i will try to get a schematic on when i get my scanner to work

Hi Latala,

No need for scanning, here it is: (the first schema)
http://skory.gylcomp.hu/25wamp/25wamp.html
The text is in hungarian...

On the margin I really agree with Darkferniz!

These parts are obsolete and it may turn out to be waste of time to build up something from these. For also very low price you will get tl07x or NE5532 op-amps, which are way better. Modern power trasistors will be probably something like 2$.

Best R.

 

[ThSpeakerDude88]

well shoot... I don't have a dual supply. I have 7812 and 7912 regulators, but that would only give me +/- 12v... I do have a 32v power supply, any way to adapt one of these to that?

also, Is there any way to do this with only 1 output transistor? what about using a power amp IC to drive the transistor.. I have a couple 25 watt ones and some 15 watt ones, as well as one TDA2050 which will do about 30 on the power supply I have. I saw somewhere on ST's website one time they had a 60 watt driver, it was just a 14 pin ic and all you needed to add was your choice of power transistors.

 

[infinia]

How about a simple op-amp driving a push pull quasi output stage. Single PS would most probably need a DC block cap on the output. I think i've seen designs like this in an older RCA app note. Up to 12-20Watts output but could be upgraded with more parts for higher power.
Signetics used to make a high voltage audio driver IC for full compl output stage NE540 I think.

 

[ThSpeakerDude88]

would it be possible to use a lower powered chipamp to drive hgher powered transistors?

 

[infinia]

I don't see why not. If used in place of a simple op amp may reduce the need for some components but you still may need a pnp driver anyway for quasi outputs. See if you can locate any designs using op-amps and take a closer look. RCA transistor manual circa 1974 is what I have. But just going on the 2 brain cells I have right now.

 

[PeteM]

Maybe this is simple enough

An externally hosted image should be here but it was not working when we last tested it.

http://www.geocities.com/leobodnar/audio_amplifiers.html