Ok, I have several SIMPLE circuits using transistors. They just use a couple PNP transistors and an NPN. SO, I hook everything up like it shows, and power it with my bench supply (9W, +/-12V power supply) and I get absolutely nothing. No sound or anything. Why might this be? I hook everything up to the right things on the transistor based upon diagrams I see... but it never works. Quite discouraging.
hey, don´t give up so fast!
post schematic and get out your meter and see what´s going on...
Jens
post schematic and get out your meter and see what´s going on...
Jens
If you've played with valves /tubes....
trespasser_guy,
I know you understand valve / tube things to an extent, from our dialogues on the Tubes forum. We determine how things are by measuring voltages with that technology, and don't (usually) have to think any farther.
With bipolar SS stuff you have to imagine the currents. Voltage measurements only tell part of the story. It's a slightly different mind-set.
As Jens said: don't give up, and post what you've tried.
But what I will add, is that you might be happier trying FET's first.
Cheers,
trespasser_guy,
I know you understand valve / tube things to an extent, from our dialogues on the Tubes forum. We determine how things are by measuring voltages with that technology, and don't (usually) have to think any farther.
With bipolar SS stuff you have to imagine the currents. Voltage measurements only tell part of the story. It's a slightly different mind-set.
As Jens said: don't give up, and post what you've tried.
But what I will add, is that you might be happier trying FET's first.
Cheers,
Post the schematic and we'll see what we can do for you...
Best regards,
HB.
BTW, my first amps didn't work either!!!
Best regards,
HB.
BTW, my first amps didn't work either!!!
I was attempting the discrete opamp shown on ESP. Using that circuit, I DID get sound... but no adjustments to the resistor values really made that sound very clear or nice. It would get louder, but not better. I also tried using an opamp and adding a Class A follower with bipolars as shown on the opamp discussion page at HeadWize. That produced no sound at all.
I was wanting to build a discrete headphone amp, or a 300W amp like the one on ESP. I am in the process of building my first sub and only have a 125W PA amp to power it, and think I might need more.
dhaen: I know a ltitle about tubes, yes... and, I should have a tube amp in my possession soon for testing purposes. It is a push-pull using 6L6's, and is rated at 60WPC. We will see. It is an old power amp, so it may need a bit of work, which is what makes this fun. 🙂
EDIT: Here is the page about the discrete opamp... as simple as it looks, I cannot get a lot out of it. Granted I don't have exactly the same transistors, either... But I went through all my resistors and it didn't improve much, and had so much DC at the output that the speaker wouldn't even play. Added a 470uF cap, and got sound... just not great sound.
I was wanting to build a discrete headphone amp, or a 300W amp like the one on ESP. I am in the process of building my first sub and only have a 125W PA amp to power it, and think I might need more.
dhaen: I know a ltitle about tubes, yes... and, I should have a tube amp in my possession soon for testing purposes. It is a push-pull using 6L6's, and is rated at 60WPC. We will see. It is an old power amp, so it may need a bit of work, which is what makes this fun. 🙂
EDIT: Here is the page about the discrete opamp... as simple as it looks, I cannot get a lot out of it. Granted I don't have exactly the same transistors, either... But I went through all my resistors and it didn't improve much, and had so much DC at the output that the speaker wouldn't even play. Added a 470uF cap, and got sound... just not great sound.
I don't believe the ESP discrete Op amp will drive low impedance loads. What were you using to not get "sound very clear or nice"?
I was using a 22-ohm speaker... and 2N3904/6 transistors... I just figured I'd throw it together and see if I could get decent sound.
The follower after the opamp, I just don't understand why it wouldn't work.
The follower after the opamp, I just don't understand why it wouldn't work.
One thing I would look at is if the output (of the D. OP Amp) is at 0.00 Volts DC.
(or add a coupling Cap)
(or add a coupling Cap)
that circuit is for a preamp. as biased, it really is not suitable for driving power into a 22ohm speaker.
you did close the feedback loop around it, right?
mlloyd1
you did close the feedback loop around it, right?
mlloyd1
trespasser_guy said:
trespasser_guy said:
Quote from the webpage: "It has not been built but should work...". Yeah, sure. Bet that that BC556 has died, what with no current limiting in its E-B path and that speaker load.
But I won't waste any more words on it. If someone is so eager to make money that he will publish untried circuits, he's not a friend of me. Should be ashamed.
Jan Didden
Says a lot, an experimental schematic that's certainly not suitable for driving loudpeakers. I think accusing Rod being so eager to make money that he will publish untried circuits is very premature. Nearly all projects are tested and built by a lot of people. He replies mail concerning projects always within a very short time. I don't think he is that eager to make money because I ordered a PCB for the P3A some time ago and IIRC it hit the bank for 25 Euro included shipping from Australia !
Transistor amp not working (PICNIC)
Very "nice" response from someone who obviously has little understanding of electronics or the philosophy of my Web site! How exactly do you think I make money from that project?
It does work, and actually has been built, and I don't charge anything for that - I don't know what medication you have stopped taking, but I suggest that you get back on it immediately.
PICNIC - Problem In Chair Not In Circuit!
The circuit described is an OPAMP! It is not (and never was) intended to drive a speaker, any more than any other opamp. Speaker drive requires a power amp (still an opamp in configuration, but with an output stage - i.e. power transistors!) The output current in the Project 07 opamp is around 11mA - that is clearly stated in the article, and it is (or should be) obvious that it cannot drive a speaker.
The circuit was published as experimental, so people could learn how to make an opamp, and understand how they work - if you fail to appreciate that, then that is your problem, not mine. It does work (quite well actually), and if used as intended you may actually learn something in the process.
Cheers, Rod
Very "nice" response from someone who obviously has little understanding of electronics or the philosophy of my Web site! How exactly do you think I make money from that project?
It does work, and actually has been built, and I don't charge anything for that - I don't know what medication you have stopped taking, but I suggest that you get back on it immediately.
PICNIC - Problem In Chair Not In Circuit!
The circuit described is an OPAMP! It is not (and never was) intended to drive a speaker, any more than any other opamp. Speaker drive requires a power amp (still an opamp in configuration, but with an output stage - i.e. power transistors!) The output current in the Project 07 opamp is around 11mA - that is clearly stated in the article, and it is (or should be) obvious that it cannot drive a speaker.
The circuit was published as experimental, so people could learn how to make an opamp, and understand how they work - if you fail to appreciate that, then that is your problem, not mine. It does work (quite well actually), and if used as intended you may actually learn something in the process.
Cheers, Rod
The speaker was a headphone speaker... I generally build headphoen amps. This is why I used it. Opamps CAN drive headphones.
No, some opamps can drive some headphones - but by no means all. Some do it vey poorly indeed. A 22 ohm headphone speaker may require up to 100mA or more peak current (depending on level). Most standard opamps can deliver +/-20mA (an average maximum power of 4.4mW), and there was a warning in the article that the discrete opamp has even less current that that.
Very few opamps will give a satisfactory level into low impedance 'phones unless a power follower is used to boost the available current.
There are several different "real" headphone amps described on the ESP site, and they will drive your 'phones with no trouble at all.
Cheers, Rod
If you look at an Aleph by Nelson Pass you will see that it is the same circuit as Rod's, just done with FETs.
If you selected the right BJTs you could drive headphones, easy.
"and had so much DC at the output that the speaker wouldn't even play"
The + and - inputs of an opamp must have a DC return path for the base currents of the diff pair. The resistor that sets the gain in a non-inverting design takes care of the - input. You probably don't have a resistor from the + input to ground. Without this the opamp will generally latch up to the supply rail.
If you selected the right BJTs you could drive headphones, easy.
"and had so much DC at the output that the speaker wouldn't even play"
The + and - inputs of an opamp must have a DC return path for the base currents of the diff pair. The resistor that sets the gain in a non-inverting design takes care of the - input. You probably don't have a resistor from the + input to ground. Without this the opamp will generally latch up to the supply rail.
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