Low Voltage Regulator Circuit Design with Op Amp, Zener Diode, JFET, BJT Transistors 

My pleasure. Glad that you liked this voltage regulator video. Here are a few more related circuit examples: Voltage Regulator Circuit Design with Op Amp and BJT Transistor ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rI9f6-DyXxQ.html Voltage Regulator designed with MOSFET, JFET transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NdfyHoxjKrY.html Current Foldback Regulator Design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RFfRrbqM_-s.html

You're welcome. Glad that you enjoyed this Voltage Regulator circuit video. Thanks also for sharing your observations. To watch an alternative design of voltage regulator please see ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RFfRrbqM_-s.html which is a Current Foldback Voltage Regulator Design with Op Amp and Darlington Transistors. I hope you enjoy this video as well.🙂

You are welcome! Glad that this video is interesting. The Push-Pull Amplifier stage that you mentioned is discussed in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8BFzsi7-Vbs.html which is the video of Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors. I hope it is interesting as well. 🙂

@@STEMprof 👍

You are welcome. Glad that you liked this video.

Thanks for the video, it is an interesting circuit

Sure, this technique is similar to the Push-Pull design in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8BFzsi7-Vbs.html. As I mentioned in the video around minute 3:50, the internal output stage inside the op amp looks similar to the NPN-PNP output stage of a power amplifier circuit (albeit with orders of magnitude less current). When voltage at inverting terminal of Op Amp is higher than the non inverting terminal, Op Amp immediately attempts to reduce its output voltage toward the negative supply voltage (in this case ground). This is achieved by reducing sourcing current from Vdd (hence reduced current through 680 ohms resistor) so that less current is provided to op amp output (resulting in reducing output voltage). This reduction of current through the 680 ohms translates to reduced voltage drop across 680 ohms resistor which means reduced voltage across the emitter-base PN junction of the main PNP BJT transistor. That translates to exponential reduction of the collector current of the main PNP transistor. which results in reduction of the voltage across the series of feedback resistors R3+R4 and hence reduced emitter voltage of the small NPN BJT transistor (which is effectively a Diode). The reduction of emitter voltage results in reduction of the voltage at the inverting terminal (counteracting the initial voltage increase) indicating a negative feedback. I hope this explanation is helpful

@@anuragmahajan5919 You are welcome. Thank you. Glad that this analog circuit video is interesting. To watch an alternative design of temperature compensated regulator circuit please see ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NdfyHoxjKrY.html which is Voltage Regulator designed with MOSFET, JFET transistors.

Good day to you as well. Thanks for sharing your thoughts. The Operational Amplifier in this circuit is wired in an overall closed loop negative feedback circuit scheme as explained in the video starting at 3:50. Nonetheless, to your point, depending on the selected Op Amp extra care is needed regarding any extra stablizing capacitors (say 10pF to 100pF) required between terminals of the selected op amp (as described in op amp datasheet).

Aside from temperature compensation, this circuit has a negative feedback loop that keeps the output voltage fixed at desired voltage while also providibg high current to the output load via PMOS transistor.