Push-Pull Power Amplifier design (High Voltage) with Op Amp and Darlington Transistors

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A high-voltage Push Pull power amplifier circuit with current limiter is analyzed in this video. This power amplifier is design with one Op Amp, NPN and PNP Darlington BJT Transistor pairs and Zener Diodes. How much this circuit amplify the input signal? What is the maximum output current of this power amplifier? How does this circuit achieve both substantial voltage and power gains? For more examples including regulator circuits see • Electrical Engineering...
The Zener Diodes in this circuit control the positive and negative supply voltages for the operational amplifier. The Op Amp stage is properly wired to have negative feedback. The overall input to output of this circuit has a negative gain to indicate a proper negative feedback in this circuit. There are two stages in this class AB amplifier by biasing both Darlington transistor pairs via chain of four diodes so they conduct when the signal is close to zero. This helps with avoiding voltage dead zones during zero crossing of the output voltage (to minimize distortion) due to limited slew rate of the op amp. The small output resistors define the maximum allowed output current of the power amplifier and also limit the quiescent current of Darlington Transistors when output is near zero or shorted. The input-output voltage transfer function of this high voltage Push-Pull Power Amplifier is derived and then analyzed to show the overall gain and also the frequency range of operation for this amplifier.

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21 окт 2024

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Комментарии : 30

@yasiruamarasinghe2285 10 месяцев назад

This is a Very Good Channel for people who are into electronic circuit design. looking forward more circuits which do interesting things. Thank you

@STEMprof 10 месяцев назад

Thank you for watching and your encouraging comment. Glad that you like this channel. For more electronic circuits, Op Amp, Diode and transistor examples pls see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these videos are useful and interesting. 🙏

@STEMprof 10 месяцев назад

Thanks for watching. For more Op Amp & Circuit Examples pls see: Push-Pull Power Amplifier Design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-866MYibo8yE.html Voltage Regulator Design with Op Amp BJT JFET ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Full-Wave Rectifier Circuit ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html Voltage Regulator design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rI9f6-DyXxQ.html Bandgap Circuit Design: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-esMlNx5w9Jw.html Analog Exponential (Anti-Log) computer ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kk2c7Gk3nW4.html PID Controller for Servo Motor explained: How does it work? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NATBlfABXrA.html Flex Voltage Regulator Example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CJl-urzeiTo.html Op Amp Analog Differential Equation solver ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.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 And my analog circuits playlist ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope the Analog Circuit Design and Analysis Examples are interesting and helpful. 🙏

@andreamarani2305 8 месяцев назад

Another great design, thank you 😀

@STEMprof 8 месяцев назад

You're welcome. Glad that this video is useful. For more analog circuits & amplifier examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt Thanks for watching 🙂

@andreamarani2305 8 месяцев назад

I'm wondering the reason for +/-125V. The circuit should be correctly polarized even with a much lower voltage just reducing the value of the two 50K resistors. Roughly, having +/-60V the circuit should work properly with two 25K resistors instead of 50K. Thanks for your opinion.

@STEMprof 8 месяцев назад

@andreamarani2305 Thanks for sharing your thoughts and your comment. There was a request to show an example of Push-Pull implementation using +/-125 volt supplies. Otherwise, I agree with you that with your suggested adjustment circuit should work with +/-60 V supplies. For more Push-pull power amplifier videos please see analog circuits playlist ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt. Thank you.

@RixtronixLAB 10 месяцев назад

Nice info, well done, thanks for sharing it with us :)

@STEMprof 10 месяцев назад

You're welcome. Thanks for watching. Glad that you like this video. For more electronic circuits, Op Amp, Diode and transistor examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these videos are useful and interesting. 🙏

@AnalogDude_ 8 месяцев назад

Cool, circuit, would this also work if you simply "rectify" 220V from a wall outlet? but is hard to divide and create a "virtual" ground, because you have no 200+V opamps. Special transformers are not easy to get.

@STEMprof 8 месяцев назад

@AnalogDude_ Glad that you liked this push pull power amplifier video. Please note that in the presented circuit op amp uses a much lower supply voltages 0f +/-15 Volt (Zener reverse breakdown voltage).

@AnalogDude_ 8 месяцев назад

@@STEMprof i meant to say an opamp to split a rectified voltage of 200V and create a virtual ground. Than it could be a transformerless amplifier.

@STEMprof 8 месяцев назад

@@AnalogDude_ Thanks for clarifying. I agree with you that Op Amp is not the best tool to split high voltage 220V DC to generate +/-110 DC supplies and virtual ground (without transformer). Because it requires hard-to find high voltage op amp like Analog Devices ADHV4702 www.analog.com/en/products/adhv4702-1.html that has supply operation range up to 220 V. Instead, I suggest supply rail splitter circuit that either directly generating both positive and negative DC voltage from the AC outlet or uses high voltage Diodes and BJT Transistors similar to the output stage of the push-pull amplifier circuit discussed in the following video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-866MYibo8yE.html. I will post a video hopefully soon. I hope this is helpful.🙏

@AnalogDude_ 8 месяцев назад

Like i said, i very much like both amplifier schematics your posted and would like to build, but one requires +/-125V and the other +/-35V and such transformers are hard to come by in a shop. i did get a +-/15 transformer a few days after your post, but these are somewhat standard. : ) @@STEMprof

@STEMprof 8 месяцев назад

@AnalogDude_ Glad that you like these Push-Pull circuit videos. I understand your point regarding the availability of 15V transformer vs higher voltage ones. In my previous message I mentioned that there are methods not requiring transformers for example using two bridges of high voltage Diodes to directly rectify AC outlet to +/-110 volt with a middle virtual ground node. I will try to post a related video in my Analog playlist. 🙋‍♂️

@paulgraf4140 6 месяцев назад

Great analysis! 👍👍👍

@STEMprof 6 месяцев назад

Thank you! Glad that you liked this Push-Pull video. More Power Amplifiers & Voltage Regulators Videos are posted in ru-vid.com/group/PLrwXF7N522y4vWr-8XRBqxpi5idFDE9BV video playlist. 🙋‍♂️

@paulgraf4140 6 месяцев назад

@@STEMprof Thank you so much! Couldn't you tell if it's possible to evaluate THD of this scheme?

@STEMprof 6 месяцев назад

@@paulgraf4140 You're welcome. THD simulation is the best way to obtain a practically meaningful & reasonably accurate Total Harmonics Distortation number. It should be a decent level though given that this design is avoiding dead zones at the output pretty well. 🙂

@paulgraf4140 6 месяцев назад

@@STEMprof Thanks!

@arashyusefi1889 3 месяца назад

Thanks 👍😊🙏💯

@STEMprof 3 месяца назад

You’re welcome 😊 Glad that you liked this Push-Pull video. More Power Amplifiers & Voltage Regulators Videos are in ru-vid.com/group/PLrwXF7N522y4vWr-8XRBqxpi5idFDE9BV video playlist.

@jackthaner4182 10 месяцев назад

How is the 1MΩ Register Works? Looks like this register is no need at all

@STEMprof 10 месяцев назад

Thanks for watching and your question. The 1Mohm resistor helps with keeping the active Diode on to minimize voltage dead zones at the output. For more examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt. I hope this clarification is helpful in answering your question.

@sc0or 9 месяцев назад

They help to short those two diodes to zero volts, not to depend on T1/2 stats. And this equalizes an idle point for the output transistors. Don’t forget that more than 120 volts are on T1/2 transistors bases. That’s pretty much for 1meg.