Push-Pull Power Amplifier with Darlington and Sziklai Transistor pairs

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A Push-Pull power amplifier designed with Op Amp, Darlington and Sziklai BJT transistor pairs are analyzed in this power amplifier example video. How does this circuit achieve both substantial voltage and power gains? For more examples including regulator circuits please see • Electrical Engineering...
In this circuit the operational amplifier is operating as noninverting amplifier t provide the voltage gain while the NPN BJT Darlington pair and PNP Sziklai pair provides the current and hence power gain needed to provide 10 watts of power to a few-ohm high-drive load (for example speaker). The very small output resistors are to limit the quiescent current and power when output is near zero or shorted.The chain of three diodes are mainly to minimize any residual output dead zones during output zero crossing due to limited slew rate of the op amp.

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12 ноя 2023

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Комментарии : 49

@shirazsohail 7 месяцев назад

Push push amplifier explained in such a detailed, first time I came across

@STEMprof 7 месяцев назад

Thanks Shiraz for watching. Glad that this Power Amplifier video is useful, glad you liked it. For more OpAmp Examples please see: PID Servomotor controller ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Capacitor to Inductor Converter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6IYz4iaa05c.html Gyrator impedance converter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-weIHG45G6Pg.html Analog Computer Differential Equation solver ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Bandgap Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Full-Wave Rectifier: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html I hope these Op Amp and Analog Circuit Examples are useful and interesting.

@DS-vu5yo 3 месяца назад

Excellent content. Thank you for putting this out.

@STEMprof 3 месяца назад

My pleasure! Glas that you liked this Push-Pull Power Amplifier video.

@wickedprotos1937 7 месяцев назад

I've been doing analog design for a long time and the PNP Sziklai pair was new to me. Thanks!!!! I had seen quasi quasi-complementary design with all N channel devices. but this was new.

@STEMprof 7 месяцев назад

Thanks Lee for watching and your comment. Glad that you like this circuit example and the Sziklai transistor pair side by side Darlington transistors. For more examples involving Darlington/Sziklai transistors please see Voltage Regulator Example ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rI9f6-DyXxQ.html Voltage Regulator Design with BJT Darlington Transistors and Zener Diodes ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ArisQp7V0Ac.html I hope these videos are useful and interesting as well 🙋‍♂️

@voice4voicelessKrzysiek 7 месяцев назад

Thank you for posting this video. I enjoyed it greatly. I would also be interested in learning more about PID controllers, as one of the commentators suggested. Again, thank you a lot.

@STEMprof 7 месяцев назад

Thanks for watching and for your comment. Please submit your topic of interest in www.youtube.com/@STEMprof/community . I am glad that this Push-Pull power amplifier circuit video is useful. Thanks also for sharing your interest in PID controllers. Sure, I will prepare a PID circuit example and will post it in my circuit video collection ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HeZRtnRXpEI.html

@STEMprof 7 месяцев назад

An example of PID controller Circuit for Servo motor: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html as requested. I hope that this circuit example video is useful. 🙂

@dnkreative 7 месяцев назад

First time I see circuit math is not boring and I didn't fall asleep

@STEMprof 7 месяцев назад

Thanks for watching. Glad that you liked this Push-Pull Amplifier video. For more Op Amp Examples please see: PID Servomotor controller ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Capacitor to Inductor Converters ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6IYz4iaa05c.html And ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-weIHG45G6Pg.html Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Analog Differential Equation solver ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Bandgap Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Full-Wave Rectifier: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html I hope these Analog Circuit Examples are interesting.

@STEMprof 6 месяцев назад

Thanks again Dmitri, I hope you also enjoy the new Push-Pull Power Amplifier video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html

@all.n.1 6 месяцев назад

Very well done💯.

@STEMprof 6 месяцев назад

You are welcome. Thanks for watching and your comment. For more Amplifier and Op Amp Examples please see: Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html , Push-Pull Power Amplifier design (High Voltage) with Op Amp and Darlington Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html PID Servomotor controller ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Capacitor to Inductor Converter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6IYz4iaa05c.html Gyrator impedance converter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-weIHG45G6Pg.html Analog Computer Differential Equation solver ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Bandgap Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Full-Wave Rectifier: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html I hope these Op Amp and Analog Circuit Examples are interesting as well.

@ivolol 7 месяцев назад

Nice practical example and derivation of values to use

@STEMprof 7 месяцев назад

Thank you for watching. Glad that this power amplifier video is useful. Here are more Op Amp circuit examples: Full-Wave Rectifier: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html Voltage Regulator: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rI9f6-DyXxQ.html Bandgap circuit Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Flex Voltage Regulator: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Op Amp Analog Computer circuit that solves Differential Equation: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Thank you 🙏

@bodzio_stawski187 5 месяцев назад

Hello, we are very grateful for the huge portion of academic knowledge in your videos about operational amplifiers! I wonder if it is possible to use two Sziklai pairs in this circuit instead of the Sziklai+Darlington variant? What consequences could this have in practice? Shouldn't this allow you to eliminate one of the three diodes (the highest on the diagram) in the diagram?

@STEMprof 5 месяцев назад

My pleasure! and you're welcome. Glad that my videos are useful. Regarding your question: Yes, it is possible as discussed in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8BFzsi7-Vbs.html which is Push-Pull Power Amplifier Design with Op Amp and Two Sziklai Darlington Transistors. And for a pure Darlington pair design please see Push-Pull Power Amplifier design (High Voltage) with Op Amp and Darlington Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html . I hope this is helpful.

@STEMprof 7 месяцев назад

Thanks for watching. For more Amplifier Circuits and Op Amp Examples please see: Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8BFzsi7-Vbs.html Push-Pull Power Amplifier design (High Voltage) with Op Amp and Darlington Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html PID Controller Circuit for Servo motor ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Bandgap Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Op Amp Analog Computer circuit that solves Differential Equation: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Full-Wave Rectifier: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html And my analog playlist ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these Analog Circuit Design and Analysis Examples are interesting and helpful. 🙏

@ivolol 7 месяцев назад

I wonder if you'd be interested in showing implementation of a design for a [simple as possible] PI loop (say, or any combination of PID you like) that could drive a simple example like powering a resistive heater so that a thermistor, or temperature chip like LM34 settles on, say, 100 F after some minutes.

@STEMprof 7 месяцев назад

Thanks for watching and your comments & suggestion. Sure, What other circuits are you interested in? I will prepare a PID controller example that shows proportional, integral, and derivative adjustment and control components for automatic compensation. I will post it in my Analog circuits videos collection ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt

@STEMprof 7 месяцев назад

PID controller Op Amp Circuit for Servo motor example video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html as I promised 🙂. I hope it is useful and interesting.

@johndavis1465 7 месяцев назад

Both R1 bias resistors and diodes not needed. Both output transistor bases are connected together then connected to opamp output.

@STEMprof 7 месяцев назад

Thanks John for watching, your interest and your comment. Diodes and R1 resistors are practically needed depending on the application (frequency, etc.) and sensitivity of that application to nonidealities. For instance Diodes help with minimizing any residual effect of the voltage dead zones during zero crossings when limited or finite slew rate of op amp has limited catch up speed to turn on Darlington or Sziklai transistors causing non-negligible zero voltage zones (dead zones) at the output. The R1 resistors also help with removing any dependency on assumptions or requirements for internal output stage of the operational amplifier. I hope this explanation is helpful. For more examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt

@michaellundsrensen2292 7 месяцев назад

I don't understand why there is one pnp and one npn transistor in the negative darlington? The Sziklai transistor. Why not use a pnp darlington? But anyway a very good educational video! But you should draw diodes smaller to give some free space - you need it!

@STEMprof 7 месяцев назад

Thanks Michael for watching and sharing your thoughts and feedback. While in a variant of this circuit it is possible to replace the Sziklai transistor pairs with a PNP Darlington BJT pair, the drawback is it equires two Vbe voltage drop (2*0.7v) as turn-on voltage instead of just 0.7v drop that Sziklair pair needs. For more circuit examples please see Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html PID Op Amp controller Circuit for Servo motor video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Bandgap Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Sawtooth Oscillator with Op Amp, JFET and BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5zHXTx-Vl20.html Op Amp Analog circuit that solves Differential Equation: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html I hope these Analog Circuit Design and Analysis Examples are interesting and useful. 🙏

@michaellundsrensen2292 7 месяцев назад

@@STEMprof I just think that the output resistance for the positive and the negative half period will be different (seen without feedback) and that the benefit of the feedback will be different for the positive and the negative half period.

@STEMprof 7 месяцев назад

@@michaellundsrensen2292 thanks Michael for thinking about it and sharing your thoughts. While, as you noted, there is asymmetry in output resistance, it doesn't seem to be at a scale to be a major practical concern. Nonetheless thank you for your detailed attention and good practical consideration.

@Chupacabras222 7 месяцев назад

How to get the value 0.3 ohms of those resistors between transistors? How to determine it?

@STEMprof 7 месяцев назад

Thanks for watching and your good question. The value of these current limiting resistors (protecting expensive high power transistors) depends on specific application, target efficiency, maximum planned current and planned quiescent (standby) current when output voltage is near zero. Ideally we want to have zero current & power consumption in standby mode. The larger this protective resistor is the less standby current we have but then the larger resistor will burn more AC power during actual operation that translates to less efficient design. In this Power amplifier example, peak transistor and load current is +/-2A which results in peak 0.6v drop across the resistor given the 0.3 ohm value. That means 0.6 Watt power is wasted as heat dissipation by the combination of two 0.3 ohm resistors. Considering that circuit is designed to deliver 10 Watts average power to then load, we are wasting 6% of power in these protective resistors. I hope this explanation is helpful.

@Chupacabras222 7 месяцев назад

@@STEMprof So, the bigger they are the better protection for transistors it is. And the smaller they are, the better efficiency there is. Correct? I thought it has something to do with feedback and minimizing cross-over distorsion. But I'm not sure.

@STEMprof 7 месяцев назад

You summarized it well. And yes, that resistor placed in the emitter in series with Vbe provides a negative voltage feedback that helps with linearizing the response of BJT transistors resulting in reduced distortion.

@everTriumph 7 месяцев назад

Now do it from 50V rails!

@STEMprof 6 месяцев назад

High Voltage Push-Pull Power Amplifier with 125V supply rails ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html Thanks for watching and your follow-up comment.

@allwaizeright9705 7 месяцев назад

I think you are missing a few DC Isolating capacitors...

@STEMprof 7 месяцев назад

Thanks @allwaizeright9705 for watching and for your comment. You have a valid point that any practical implementation of a power amplifier surely requires Bypass caps and DC isolating caps. There are many other practical aspects like BW, stability, noise, efficiency & power consumption, and heat dissipation that are required to be considered for a functional implementation of a Power amplifier. For more examples please see ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HeZRtnRXpEI.html Thanks for watching.

@STEMprof 6 месяцев назад

Thanks again, I tried not to miss them in the new PushPull Amplifier example ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C9Hse91r5sA.html

@4Nanook 7 месяцев назад

You can get 20 watts from a pair of LM383's, no extra transistors, much cheaper and simpler.

@STEMprof 7 месяцев назад

Thanks for watching and sharing your thoughts. The National Semiconductor LM383 IC is an implementation of Power Operational Amplifier with two PNP-type Sziklai transistor pairs as its output stages. It does not have internal gain control. You need to properly wire it in a similar noninverting topology or two of them in a Bridge Amplifier scheme to get the desired voltage and power gains. I will post more examples in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HeZRtnRXpEI.html Thanks again.

@brucemblue 7 месяцев назад

I find it interesting just to see how some of the calculations are made in the analog world. However, I think this amp will eventually encounter thermal runaway of the diodes are not connected to the heatsink (so in that sense this is an academic discussion and not a practical one) and an explanation of why that happens and how to prevent it would also be interesting to me.

@brucemblue 7 месяцев назад

There are much much better amplifiers than the LM383 out there for similar power levels (e.g. the TDA series and class D amps for battery powered circuits.) Conversely, most amplifiers in AV receivers use discreet transistor circuits like this one. If one were wanting to repair that sort of equipment this knowledge would be helpful.

@STEMprof 7 месяцев назад

@@brucemblue Thanks Bruce for watching and your comments. You are right that further practical considerations need to be taken into account for real-world implementation of push-pull power amplifiers. For instance bandwidth and slew rate, noise, THD, possible zero crossing and dead zone issues, etc. Having said that, Diode thermal issue is not a major concern at least in this example because even at maximum power delivery to the load, the current through each 0.7v Diode just varries between 1mA and ~25mA (roughly a 13mA DC component and +/-12mA peak AC component). So thermal wise it should be alright.

@STEMprof 7 месяцев назад

@@brucemblue Thank you for sharing your thoughts and for highlighting the availability of better power amplifiers like the Philips' TDA series audio amplifier ICs including the TDA2003/5 and TDA2030/50 and the higher power TDA7294 Power Amplifier IC. I will post more examples in the circuit video collection ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HeZRtnRXpEI.html Thanks again.