A very interesting circuit configuration. I have a couple of questions about it. But fist: I appreciate the kind of music you have used for sound testing. 1. A recommendation: it is better to use an input capacitor, because also your source can have a dc contribution. 2. Why do you use the inverting amplifier configuration? The booster transistors also work in non-inverting configuration. In non-inverting configuration you can also use an electrolytic capasitor to ground in the feedback voltage divider to set the offset amplification to 1. 3. Why are R8 and R9 in this circuit position? In the "classic" emitter follower configuration they are used to stabilize the bias current in the output stage. If you intend to do the same in your circuit they should be placed between the emitter and the voltage rails of the output transistors. I think in this circuit they are not necessary because the boosters are off at zero input signal. 4. In order to get more output power you can use a Sziklai-configuration in the output stage instead of a Darlington-configuration. Probably you can also use only power BJTs if you use the combination of D44VH10 / D45VH10. These BJTs have a current gain of 200 at 1 A and 100 at 4 A. I think this could be enough with an adaption of R3, R6 and R7. 5. I think you can eliminate R3 and C2 and connect the output of the opamp directly to the collectors of the output transistors. So the speaker is directly driven by the output current of the op amp until a certain value (20 to 40 mA) is reached. You can use the LM4562 (one channel as amplifier the second channel as voltage follower in parallel, outputs separated by 1 Ohm resistors) to drive up to 50 mA. At this output current the booster stage sets gradually in and contributes to higher currents. The LM4562 is also fast enough (20 V/µs) to suppress crossover distortions. It has also low noise, low offset and a very high open loop gain for low THD+N. I can send you (or other interested people) a circuit suggestion by e-mail if you don't mind.
I am using Tektronix TDS 524 Oscilloscope which has a VGA output to a monitor. You should consult your USB scope manual. Sorry I couldn't be more of a help!
You definitely can use it! But you might want to use a pre-amp to drive the power amplifier shown in the video because your guitar pickup might not put out strong enough signal to drive the power amplifier directly. To give you an idea on the sensitivity of the power amplifier: for a 36Watt output power in to 4Ω speaker, the amplifier would need at least 155mVp-p signal amplitude at the input.
Yes that will work. To get a good performance, the first stage should be a circuit with good signal to noise ratio. Instead of using op-amp for the first stage you should use a JFET or BJT single transistor amplifier. Take a look how to design such an amplifier in my latest videos on common emitter amplifier design using BJT.
Not really. The operational amplifier is used as voltage amplification stage of the power amplifier which has non traditional common emitter based output transistors.
The 'LM' indicates the 741 opamp is made by National Semiconductors (datasheet: pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS009341.PDF ). National Semiconductors have been bought out by Texas Instruments I think 3 years ago.
Sure for most people it means National Semiconductors. But to dig deeper. LM means Linear Monolithic LH means Linear Hybrid LMH means Linear Monolithic High-Speed
![Quando Rondo - Life Goes On [Official Music Video]](http://i.ytimg.com/vi/eIf3fhMXAow/mqdefault.jpg)
A very interesting circuit configuration. I have a couple of questions about it. But fist: I appreciate the kind of music you have used for sound testing.
1. A recommendation: it is better to use an input capacitor, because also your source can have a dc contribution.
2. Why do you use the inverting amplifier configuration? The booster transistors also work in non-inverting configuration. In non-inverting configuration you can also use an electrolytic capasitor to ground in the feedback voltage divider to set the offset amplification to 1.
3. Why are R8 and R9 in this circuit position? In the "classic" emitter follower configuration they are used to stabilize the bias current in the output stage. If you intend to do the same in your circuit they should be placed between the emitter and the voltage rails of the output transistors. I think in this circuit they are not necessary because the boosters are off at zero input signal.
4. In order to get more output power you can use a Sziklai-configuration in the output stage instead of a Darlington-configuration. Probably you can also use only power BJTs if you use the combination of D44VH10 / D45VH10. These BJTs have a current gain of 200 at 1 A and 100 at 4 A. I think this could be enough with an adaption of R3, R6 and R7.
5. I think you can eliminate R3 and C2 and connect the output of the opamp directly to the collectors of the output transistors. So the speaker is directly driven by the output current of the op amp until a certain value (20 to 40 mA) is reached. You can use the LM4562 (one channel as amplifier the second channel as voltage follower in parallel, outputs separated by 1 Ohm resistors) to drive up to 50 mA. At this output current the booster stage sets gradually in and contributes to higher currents. The LM4562 is also fast enough (20 V/µs) to suppress crossover distortions. It has also low noise, low offset and a very high open loop gain for low THD+N.
I can send you (or other interested people) a circuit suggestion by e-mail if you don't mind.
Great! How did you home in to the driver transistors to be the cause of the higher frequency harmonic distortion and not any other components?
Sir, i tried ur schematic on multism, the output is smaller than the input. May u give me some advice? what i did wrong?
Great work.
Super
Ummm ... How to put sine wave + harmonic graphics in one screen together? I use USB scope, can I do that?
I am using Tektronix TDS 524 Oscilloscope which has a VGA output to a monitor. You should consult your USB scope manual. Sorry I couldn't be more of a help!
sir how to choose good impedance for amplifier
pls explain type of op amp for example invertin amplifier
Can i use it for guitar amp please reply
You definitely can use it! But you might want to use a pre-amp to drive the power amplifier shown in the video because your guitar pickup might not put out strong enough signal to drive the power amplifier directly. To give you an idea on the sensitivity of the power amplifier: for a 36Watt output power in to 4Ω speaker, the amplifier would need at least 155mVp-p signal amplitude at the input.
Smith Kerona what if i make two stages of op amps 1st to amplify guitar pickup sound & other to amplify the total sound
Yes that will work. To get a good performance, the first stage should be a circuit with good signal to noise ratio. Instead of using op-amp for the first stage you should use a JFET or BJT single transistor amplifier. Take a look how to design such an amplifier in my latest videos on common emitter amplifier design using BJT.
Smith Kerona thanks for helping me
Anytime!
so basically this is the preamp operational amplifier?
Not really. The operational amplifier is used as voltage amplification stage of the power amplifier which has non traditional common emitter based output transistors.
Please explain LM380 Audio power amplifier
What does LM indicates?
The 'LM' indicates the 741 opamp is made by National Semiconductors (datasheet: pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/DS009341.PDF ). National Semiconductors have been bought out by Texas Instruments I think 3 years ago.
Sure for most people it means National Semiconductors. But to dig deeper.
LM means Linear Monolithic
LH means Linear Hybrid
LMH means Linear Monolithic High-Speed
sir how to calculate indictor