Your tutorials seem to come at just the right time..five minutes ago I gave up on my amp circuit...couldn't get it right....this circuit looks way better than what I had...trying to get a 9.5 mm mic amped up to drive an 8 ohm speaker...
Ok I can see that the compensating diodes are required for a smooth transition. But WHY and how do they fix the problem? Best Wishes n Blessings. Keith
Here is a way to look at it. Note: that both the transistors have what look like diodes inside. Well in effect they act just like diodes as the transistors will not conduct until input voltage reaches at least 0.6/0.7 volts. That is why we get little kinks shown on scope. So adding in those two extra diodes means that they also will not conduct until the voltage rises across them to be 0.6/0.7. This means the input voltage is then always held just at this level of threshold voltage. Now since there are two transistors between + and ground you need two of those diodes to match the same voltage as the transistors. Hence you then get a smooth output.
Best teacher on the net! Thanks for sharing this! I think this is the problems i have at my poweramps, I have looked and measured, But I dident think about this!
I have once watched an audio circuit that uses magnetic type (center tapped trans) as push-pull's load. Static type has actually cross over as this video, courtesy of you.
As long as the diodes are forward bias, either side or between the diodes will work. I think this video will answer your question. How can a DIODE pass an AUDIO SIGNAL UNDISTORTED ruclips.net/video/ddfrkGkAvZY/видео.html
This video I used FreeHand 11, but I have recently started using CorelDraw Essentials. I also use PhotoshopElements and PremiereElements. This video is and example of CorelDraw. Triode Tube Amplification Visual Demo ruclips.net/video/4FkD0LRiu7A/видео.html
thank you very much. One question/remark : When the top transistor is conducting more, the "resistance" of the bottom one is kind of increasing (as it is actually kind of "blocking"), this mean that the extra current that Top transistor generates is actually "directed" to the load as it cannot go down ? Is that correct ? Thx
Thanks for this video. I tried building this but my results were barely audible. The transistors used were not exactly matching. They were 230 and 240 respectively. When I built the schematic on breadboard I used my phone as a sound source and a mono 8ohm speaker as the listening device.The circuit barely produced any sound being driven by my phone with the volume maxed out. Also, I removed the 100k resistor before the output and tried replacing with a potentiometer. It did nothing at all. The sound through the circuit was the same with the resistor to ground, without the resistor, and also the same with the pot. It didn't make any difference. Do you have any idea what I'm doing wrong? Thanks for your time.
Ohms Law. You start by working backwards. What is it that you going to drive with your amplifier? What is its impedance, this determines, in this amp, the Emitter voltage. Then with the specifications from the manufacturer of the transistors you can determine what the Base voltage should be to forward bias the E B junction. Now you need to known the impedance of the input signal to determine the two voltage bridge resistors that will supply the Base bias voltage. This two resistors impedance should match the input signal impedance for the most signal transfer to the base of the transistors. The best way to learn how to build amplifiers is to build some.
Hi! I have some questions. Audio source has a + and a -. It sends signal from + to -. It's push type? And at audio amplifiers it's the same. It pushes the speaker. Push pull it's when + and - switch to - and + signal and back? To push and pull the speaker?
This setup has two 12VDC supplies. They are connect together in series so if you measured from + to - you would read 24VDC. The ground is in the middle of the two power supplies. If you put a meter, the black lead on the ground and the other lead on +, it will read +12VDC. If you put the black lead on the ground and the other on -' the meter will read -12VDC.
@@AllAmericanFiveRadio I was writing about the output signal. On + it goes from 0 to + and back to 0 and to + and back to 0. Or it goes from 0 to + to 0 to - to 0? The speaker is just pushed or it's pulled too?
@@Enigma758 I know it does not seem right, but that's what makes it so interesting. Those diodes compensates for the EB junctions of both transistors. Each are about 0.7VDC. The best way to understand this circuit is to build it and experiment. I did a video on Crossover Biasing Compensating Diodes, here's the link. ruclips.net/video/v2mITbaCHUE/видео.html
Hi, I have a jukebox that uses a tube amp. For the life of me I can't get it to work. I am considering either sending it out for repair (EXPENSIVE) or replacing it with a mosfet amp. Just curious if you have an opinion of the pros and cons of doing this. Thanks, and as always love your vids.
These two videos may help. Crossover Biasing Compensating Diodes ruclips.net/video/v2mITbaCHUE/видео.html How can a DIODE pass an AUDIO SIGNAL UNDISTORTED ruclips.net/video/ddfrkGkAvZY/видео.html
It does not matter if the input is between the diodes or on one side. These two videos should help you understand this circuit. How can a DIODE pass an AUDIO SIGNAL UNDISTORTED ruclips.net/video/ddfrkGkAvZY/видео.html Crossover Biasing Compensating Diodes ruclips.net/video/v2mITbaCHUE/видео.html
It does not matter if the input is between the diodes or on one side. These two videos should help you understand this circuit. How can a DIODE pass an AUDIO SIGNAL UNDISTORTED ruclips.net/video/ddfrkGkAvZY/видео.html Crossover Biasing Compensating Diodes ruclips.net/video/v2mITbaCHUE/видео.html
@4.32 ..can anyone pls explain me in that diagram....from which point we collected the output from that npn transistor ?is it not that we collect the out always from the collector ...be it npn or pnp?...pls guide...thank you
@@phillipneal8194 You will need at least one RF choke coil. This is to keep the RF from getting into (shorted out by) the power supply. What frequencies are you interested in using?
I know it is an old video... very well done, but I have a question, if you can reply will be very appreciated... Which is the purpose of the two 470ohm resistors on the emitters? Are they used to "control" the differences in any way ? Thank you
Thanks for your response. I tried only in LTSpice and nothing sensible happened. For this reason I suspected it was for thermal runavay compensation. Is it right ?
The output impedance of the driving stage should mach the input impedance of the next stage. This transfers the most signal possible. Look up the input impedance of the transistor or MOSFET your using.
I just got so confused, I can barely stand up. I need a shower for this. There were no diodes to begin with and therefore there were 2 bumps showing in the sine wave. Unless I did not hear that nor saw that correctly. Then to clear that bumps you showed 2 diodes to be installed in series along between the bases. I don't know if I saw and heard that right either. Then you showed in your bread board mentioning that you actually installed the diodes but shorted out... whatever that means. Why did you install it shorted out. Unless installing it in series means shorted out in the first place... but that is....confusing regardless... I don't know what to even say... here. So you end up showing that you are removing the diodes that you wanted to be there in the first place to remove the bumps. But only by removing it you smoothed out the sine wave. End up with no diode that you started in the first place that caused the bumps to be there. I AM LOST. AM I SO GONE IN THE HEAD OR WHAT THAT I SEE AND HEAR THINGS THAT DON'T EXIST. I DON'T SEE ANYBODY ELSE COMPLAINING HERE.
this doesn't make sense... you would think the bias input had to be located between the diodes as opposed to two diodes in line on one bias blocking negative input voltage swing
I made this purposely this way. When the diodes are forward bias they are pretty much just a wire. So it does not matter as long as the two diodes are series biased together.
Your tutorials seem to come at just the right time..five minutes ago I gave up on my amp circuit...couldn't get it right....this circuit looks way better than what I had...trying to get a 9.5 mm mic amped up to drive an 8 ohm speaker...
This video explains the push pull configuration of amplifiers the best way it can be explained. The experiment is terrific !
Thank you, and your welcome.
You may like this video also.
MOSFET Push Pull Amplifier Visual Demo
ruclips.net/video/-6N7l1dnk6s/видео.html
Great teaching and I could barely wait till you pulled the jumpers!
THANKS!!
Really well put together.....easy to follow, nice visuals and slow clear concise voice...thank you very much.
Take a look at this video
MOSFET Push Pull Amplifier Visual Demo
ruclips.net/video/-6N7l1dnk6s/видео.html
Thank you for this video, the compensating diods are very well explained in your comments as well. Best regards.
Thank you!
Ok I can see that the compensating diodes are required for a smooth transition. But WHY and how do they fix the problem? Best Wishes n Blessings. Keith
Here is a way to look at it. Note: that both the transistors have what look like diodes inside. Well in effect they act just like diodes as the transistors will not conduct until input voltage reaches at least 0.6/0.7 volts. That is why we get little kinks shown on scope. So adding in those two extra diodes means that they also will not conduct until the voltage rises across them to be 0.6/0.7. This means the input voltage is then always held just at this level of threshold voltage. Now since there are two transistors between + and ground you need two of those diodes to match the same voltage as the transistors. Hence you then get a smooth output.
Been doing electronics for over 30 years and never know that. You explained it very well and simply for me, thanks. Best Wishes n Blessings. Keith
Your welcome!
How does diode speed effect this? Diodes are not instantaneous.
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
Brilliant! I've been looking for this schematic for weeks. Many thanks!
Thanks
Thank you. Helps to understand the way you presented it.
Thank you and you're very welcome.
Sir, You make very good videos and incredible good descripions too.Thank You
Superb, you made it very clear, and the presentation was excellent, as always, much appreciated, thank you.
Very good explanation sir. Thanks.👍👍
Thanks and your welcome.
Nagyon ügyes , értelmes és érthető videó ez tetszik! Greeting from Hungary ;)
Thanks
Very well-detailed and Merry Christmas!
And a very Merry Christmas to you Miguel
Many thanks for your video. What sort of transistor part numbers are normally suitable for such an amplifier circuit?
Very well explained as usual.
Thanks
Sir, no one could have explained it any better than you. my respect to you. I thouroughly enjoy your videos. thank you.
wow, very informative and great as always!
The ground is symbol on the negative lead is confusing to me. Is this a split-rail DC design or not?
At 6:10 you can see the power setup on the trainer. Just positive and negative ground.
Best teacher on the net! Thanks for sharing this! I think this is the problems i have at my poweramps, I have looked and measured, But I dident think about this!
Thanks
Class AB amplifier, the best transistors is using npn 2n3055 & pnp MJ2955 😊 can power 50 watt 👍😁🔊🎶🎶🎶 hahaha
I have once watched an audio circuit that uses magnetic type (center tapped trans) as push-pull's load. Static type has actually cross over as this video, courtesy of you.
Thank you for explaining. But shouldn't that 470 Ohm resistor at PNP transistor be connected between GND and collector?
OK never mind I was missing the input cap and had no 6V offset. That's why it didn't work for me :)
Both half of the Push Pull are a mirror image of each-other
Good experiment
Great tutorial! Question: Isnt the input supposed to be between the diodes?
As long as the diodes are forward bias, either side or between the diodes will work. I think this video will answer your question.
How can a DIODE pass an AUDIO SIGNAL UNDISTORTED
ruclips.net/video/ddfrkGkAvZY/видео.html
What software are you using to display the schematic and components?
This video I used FreeHand 11, but I have recently started using CorelDraw Essentials. I also use PhotoshopElements and PremiereElements.
This video is and example of CorelDraw.
Triode Tube Amplification Visual Demo
ruclips.net/video/4FkD0LRiu7A/видео.html
thank you very much. One question/remark : When the top transistor is conducting more, the "resistance" of the bottom one is kind of increasing (as it is actually kind of "blocking"), this mean that the extra current that Top transistor generates is actually "directed" to the load as it cannot go down ? Is that correct ?
Thx
Wouldn't the final circuit have the signal input between the diodes?
Don't matter
Thanks for this video. I tried building this but my results were barely audible. The transistors used were not exactly matching. They were 230 and 240 respectively. When I built the schematic on breadboard I used my phone as a sound source and a mono 8ohm speaker as the listening device.The circuit barely produced any sound being driven by my phone with the volume maxed out. Also, I removed the 100k resistor before the output and tried replacing with a potentiometer. It did nothing at all. The sound through the circuit was the same with the resistor to ground, without the resistor, and also the same with the pot. It didn't make any difference. Do you have any idea what I'm doing wrong? Thanks for your time.
This circuit is more for a oscilloscope demonstration. The impedance of the speaker may be the problem.
awesome, learned about compensating diodes
Thank you. I have a video on compensating diodes.
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
Mr. McWhorter could you please tell me what the part numbers you used for the transistors and diodes. Thank You!
NPN 2N2222, PNP 2N2907, Diodes 1N4003
How are the resistors calculated for both the base biasing and emitter side?
Ohms Law. You start by working backwards. What is it that you going to drive with your amplifier? What is its impedance, this determines, in this amp, the Emitter voltage. Then with the specifications from the manufacturer of the transistors you can determine what the Base voltage should be to forward bias the E B junction. Now you need to known the impedance of the input signal to determine the two voltage bridge resistors that will supply the Base bias voltage. This two resistors impedance should match the input signal impedance for the most signal transfer to the base of the transistors.
The best way to learn how to build amplifiers is to build some.
A big question can push pull use to make a ac signal to drive mosfet
MOSFET Push Pull Amplifier Visual Demo
ruclips.net/video/-6N7l1dnk6s/видео.html
Hi! I have some questions.
Audio source has a + and a -. It sends signal from + to -. It's push type? And at audio amplifiers it's the same. It pushes the speaker.
Push pull it's when + and - switch to - and + signal and back? To push and pull the speaker?
This setup has two 12VDC supplies. They are connect together in series so if you measured from + to - you would read 24VDC. The ground is in the middle of the two power supplies. If you put a meter, the black lead on the ground and the other lead on +, it will read +12VDC. If you put the black lead on the ground and the other on -' the meter will read -12VDC.
@@AllAmericanFiveRadio I was writing about the output signal. On + it goes from 0 to + and back to 0 and to + and back to 0. Or it goes from 0 to + to 0 to - to 0? The speaker is just pushed or it's pulled too?
@@VisnitchiRaul Oh OK.
This video may help.
MOSFET Push Pull Amplifier Visual Demo
ruclips.net/video/-6N7l1dnk6s/видео.html
Shouldn't the input be between the two diodes?
You can put the input in the middle. Both diodes are biased on, so both are like a wire.
@@AllAmericanFiveRadio Yes, but keeping it to one side, wouldn't there be an offset due to the diode drops?
@@Enigma758 I know it does not seem right, but that's what makes it so interesting. Those diodes compensates for the EB junctions of both transistors. Each are about 0.7VDC. The best way to understand this circuit is to build it and experiment. I did a video on Crossover Biasing Compensating Diodes, here's the link.
ruclips.net/video/v2mITbaCHUE/видео.html
What if the wave is a square wave, will adding the diodes be necessary??
Yes, and here is why.
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
Great you video I like thank you
Thank you!!!
Very well explain. Thunks
Thanks
Hi,
I have a jukebox that uses a tube amp. For the life of me I can't get it to work. I am considering either sending it out for repair (EXPENSIVE) or replacing it with a mosfet amp.
Just curious if you have an opinion of the pros and cons of doing this. Thanks, and as always love your vids.
Would it be possible to send me the schematic of the amplifier? If so we could check a few things in the circuit.
allamericanfiveradio@yahoo.com
awsome....but what is forward bias?
There are two 100K resistors in a bridge which makes the base of both transistors at 6VDC.
how did compensating diodes work?
These two videos may help.
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
How can a DIODE pass an AUDIO SIGNAL UNDISTORTED
ruclips.net/video/ddfrkGkAvZY/видео.html
Thanks for this video! I needed this circuit.
BTW: The powered breadboard brought back memories. Is it, by any chance, the old Heathkit model?
Thanks.
Yes it is a Zenith / Heathkit Laboratory Breadboard ET-3300
shouldn't the input be plugged between the two DIOD's ?
It does not matter if the input is between the diodes or on one side. These two videos should help you understand this circuit.
How can a DIODE pass an AUDIO SIGNAL UNDISTORTED
ruclips.net/video/ddfrkGkAvZY/видео.html
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
what is that software you are using for an oscilloscope??????
Hantek 6022BE PC Based USB Digital Oscilloscope
ruclips.net/video/nQ0-rD39yvU/видео.html
purpose of 470 ohm resistors ?
Current limiting
@@AllAmericanFiveRadio ok, but why is that required ? speaker is already limiting enough current.
@@iceberg789 Do some experimenting, take them out of the circuit and see what happens.
what would happen if the capacitor is placed between the two diodes
Little to nothing. I think this video may help.
How can a DIODE pass an AUDIO SIGNAL UNDISTORTED
ruclips.net/video/ddfrkGkAvZY/видео.html
Nicely done!
Thank you, and your welcome.
Does the gain of the transistors need to be the same?
Matched betas would be best. But if the betas are close it will still work.
I don't understand why 2 x serial Diods with same direction?
It does not matter if the input is between the diodes or on one side. These two videos should help you understand this circuit.
How can a DIODE pass an AUDIO SIGNAL UNDISTORTED
ruclips.net/video/ddfrkGkAvZY/видео.html
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
How are the values of the R and C are chosen?
Biasing an Audio Transistor
ruclips.net/video/KtXE7s5DlcI/видео.html
Biasing Basics, Class A
ruclips.net/video/Mah6TXRBXHs/видео.html
MOSFET Biasing Experiment
ruclips.net/video/nA9BBv4tPc8/видео.html
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
@4.32 ..can anyone pls explain me in that diagram....from which point we collected the output from that npn transistor ?is it not that we collect the out always from the collector ...be it npn or pnp?...pls guide...thank you
If it is not Push Pull.
MOSFET Push Pull Amplifier Visual Demo
ruclips.net/video/-6N7l1dnk6s/видео.html
@@AllAmericanFiveRadio thank you for your response...I think I need to revisit the topic
are these different with class b and ab?
That maybe a problem with B or AB. The diodes must be biased on all the time.
Can you explain how can the pnp conduct if both the load and the pnp collector are grounded ? If there's no voltage drop how can there be current ?
There are two 12VDC power supplies in series, and the ground is in the center between the two power supplies.
AllAmericanFiveRadio thank you sire
Your welcome.
Will this work at hf frequencies ?
This is an audio amplifier. Are you wanting to build a HF amplifier?
@@AllAmericanFiveRadio Yes. But I would like to build it without coils.
@@phillipneal8194 You will need at least one RF choke coil. This is to keep the RF from getting into (shorted out by) the power supply. What frequencies are you interested in using?
20 meter WSPR frequency band , 14.0970-14.0972 Mhz
@@phillipneal8194 Here is an item that you maybe interested in.
RF Broadband Power Amplifier 25 W 1.0 to 200 MHz 50V
www.ebay.com/itm/135125392109
Are the inputs and outputs referenced with respect to ground ( - )
Yes
YESS. Tank you for video. 👏👏👏
Your welcome and thanks
I see AA5 in my search results, I click.
Thank you.
Thanks. its very usefull
Thank you, and your welcome.
I know it is an old video... very well done, but I have a question, if you can reply will be very appreciated...
Which is the purpose of the two 470ohm resistors on the emitters? Are they used to "control" the differences in any way ?
Thank you
Emitter Base Bias
Take out the resistors and see what happens.
Thanks for your response. I tried only in LTSpice and nothing sensible happened. For this reason I suspected it was for thermal runavay compensation. Is it right ?
@@MrZiolelle There's no substitute for a real circuit.
@@AllAmericanFiveRadio I totally agree with you
thank you so much for your help
Thanks
please we need to find driving for rules of power amplifier
The output impedance of the driving stage should mach the input impedance of the next stage. This transfers the most signal possible. Look up the input impedance of the transistor or MOSFET your using.
But Why do it that way??Why Push Pull Method??
Bigger swing in current.
I just got so confused, I can barely stand up. I need a shower for this.
There were no diodes to begin with and therefore there were 2 bumps showing in the sine wave. Unless I did not hear that nor saw that correctly.
Then to clear that bumps you showed 2 diodes to be installed in series along between the bases. I don't know if I saw and heard that right either.
Then you showed in your bread board mentioning that you actually installed the diodes but shorted out... whatever that means. Why did you install it shorted out. Unless installing it in series means shorted out in the first place... but that is....confusing regardless... I don't know what to even say... here.
So you end up showing that you are removing the diodes that you wanted to be there in the first place to remove the bumps. But only by removing it you smoothed out the sine wave. End up with no diode that you started in the first place that caused the bumps to be there.
I AM LOST.
AM I SO GONE IN THE HEAD OR WHAT THAT I SEE AND HEAR THINGS THAT DON'T EXIST. I DON'T SEE ANYBODY ELSE COMPLAINING HERE.
Crossover Biasing Compensating Diodes
ruclips.net/video/v2mITbaCHUE/видео.html
Brilliant!!!
Thanks
this doesn't make sense... you would think the bias input had to be located between the diodes as opposed to two diodes in line on one bias blocking negative input voltage swing
I made this purposely this way. When the diodes are forward bias they are pretty much just a wire. So it does not matter as long as the two diodes are series biased together.
🙏
Thank you, and your welcome.
Thanks.
Thank you.
thanks a lot ...
Thank you, and your welcome.