Thanks for watching, your interest, insightful comments & feedback. Please NEGLECT 11-15v assumption for input supply range. DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as Darlington Transistor power consumption is below the maximum allowed. The current foldback feature kicks in otherwise to limit the output current. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Temperature-Independent Current Circuit Design with Op Amp, BJT, Zener, Schottky Diodes ua-cam.com/video/hFbnjbddUvs/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html How to find Bode Plot, Freq Response, Transfer Function of Analog Filters ua-cam.com/video/vZFkPeDa1H8/v-deo.html Universal Analog Filter Design ua-cam.com/video/2J-0msXZE2o/v-deo.html Laplace Transform Example and S-domain circuit analysis: ua-cam.com/video/ps8N5TPM_qU/v-deo.html Op Amp circuit Bode Frequency plot ua-cam.com/video/BLVzuuqAlZs/v-deo.html Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html Analog Computer to Raise Signal to power n ua-cam.com/video/IUTlBH1UraE/v-deo.html Triangle Oscillator Op Amp circuit ua-cam.com/video/JF5Up_cuL9k/v-deo.html Differential Equation Solver Analog Circuit ua-cam.com/video/R3X5AYNZGEI/v-deo.html Complex Sinusoid Oscillator ua-cam.com/video/GXRhmwmS5Zk/v-deo.html Sawtooth Oscillator Design ua-cam.com/video/2eUsGPfqbW4/v-deo.html Full-Wave Rectifier circuit example ua-cam.com/video/DJJMNU-CYcg/v-deo.html Sawtooth Waveform Generator design with OpAmp, JFET, BJT ua-cam.com/video/5zHXTx-Vl20/v-deo.html op amps Circuit with feedback loops to design an analog computer that solves a second order differential equation ua-cam.com/video/HeZRtnRXpEI/v-deo.html For more analog circuits and signal processing examples see: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these Circuit design and analysis videos are helpful. 🙋♂
Thank you. Glad that you liked this video. For more examples please see: Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html Voltage regulator design without Op Amp ua-cam.com/video/ArisQp7V0Ac/v-deo.html Voltage Regulator design with Op Amp BJT JFET and Zener Diodes ua-cam.com/video/CJl-urzeiTo/v-deo.html I hope these additional examples are interesting. 🙋♂️
Love your videos. Correct me if I’m wrong but when you are supplying the positive rail of the operational amplifier 11V you can’t regulate Vout because you need 2VBE + Vout > 11V at the output of the op-amp.
Thanks Marcos for watching, your encouraging comment and good question. Glad that you like my videos 🙂 It is always important to double-check BJT Collector-Emitter voltage requirements. Please NEGLECT 11-15v assumption for input supply range. Our DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For another example please see Voltage Regulator Design with Op Amp and BJT ua-cam.com/video/rI9f6-DyXxQ/v-deo.html . I hope this is helpful. Thanks again for your interest & follow-up comment. 🙋♂️
@@STEMprof I'm sorry, but you're wrong. At the max current (1 A) and nominal Vout (10 V), the VCE of the MJE will be over 3 V, while the VBE of the same transistor will be over 2 V (page 2 of the component datasheet). Then you have to add even the drop on sensing resistor that is over 2 V too. So, the minimum supply voltage has to be the greater than (10 + 2 + 3) V = 15 V. Another flaw is when you say that the power dissipated by the sensing resistor is negligible in the calculation of the power dissipated by T1: it is not. At 1 A of load current, the transistor dissipates 1 A x (15 - 10 - 2) V = 3 W, while the sensing resistor dissipates 1 A x 2 V = 2 W: they are almost the same. A revision is needed.
@@giorgiocanal1659Thanks Giorgio for watching, your detailed attention & insightful feedback. You have a good point. Pls NEGLECT 11-15v assumption for input supply range. DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html AbdcAnalog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html Thanks again. I appreciate your attention and feedback. 🙋♂
@marcos010697 Thanks again Marcos for your detailed attention & insightful feedback. You have a good point. Please NEGLECT the 11-15v assumption for input supply range. Our DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html Thank you again. I appreciate your attention and feedback. 🙏👍
I think you need a resistor at the output of your opamp. Opamps are voltage devices and their output have ideally zero resistance. You cannot pull down the current through T3. However, real opams have about 100 ohm output resistance.
Thanks for watching and sharing your thoughts and practical suggestions. This example relies on the fact that a reasonably selected Op Amp has few hundred ohm output resistance and say 10-20 mA max output Op Amp current that is usually specified in Op Amp datasheet. In such case BJT transistor T3 is able to redirect current to limit the output current. Nonetheless, it is a good practice to have a reasonable resistor (say few hundred ohm to 1 kilo ohm) in series at the output of operational amplifier. (Side note: there are different types of operational amplifiers including transconductance op amps that deliver currents at the output). For more op amp circuits please see ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope this clarification and further examples are helpful. Thanks again 🙏
You are welcome. Thanks for watching. Glad that this video is helpful. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these circuit videos are interesting as well.
Awesome as always. I am trying to describe how T3 works. T3 normally in many designs just senses the voltage drop in the shunt resistor (r in this case) until this reaches 0.6v, but now the base is tied to a node (between R1 and R2) and is not sensing the current proportional any more. T3 now has information from Imax and Vo at the same time(eq.1)? maybe that is why is called "current foldback"?. Thank you a lot, my friend!
You're welcome. Thanks for watching and your good questions. BJT Transistor T3 is off during nominal operation of this foldback regulator. As soon as the output current reaches the max allowed one Amp the voltage at the T1 Darlington transistor emitter (Ve1) reaches nearly 10+2.05*1 = 12.05 volts. Then the T3 Base voltage becomes R2/(R1+R2)*12.05v = 0.88 *12.05 = 10.6 volt =Vb3 while Ve3 = Vout = 10 volt. Therefore Base-Emitter voltage of BJT Transistor T3 is Vbe3 = Vb3 - Ve3 = 10.6 -10 = 0.6 volt which is the onset threshold to turn on the T3 transistor that then draws current from the base of Darlington pair and hence limits the output current. For more Op Amp Circuits please see: Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope this explanation and these circuit videos are helpful. 🙏
Again, I greatly enjoyed your analysis, since this is new to me. In the past, I could do a simple analysis of transistor-based circuits without feedback. With the feedback, it is a little more involved. It would be helpful if you could explain how the circuit would respond along the whole range of loads, not just two boundary cases. Also, I am confused about your usage of the "power" of the regulator (power supply). I would expect that we are talking about max power that could be delivered to the load, not dissipated in some internal circuitry, such as a pass transistor. Could you elaborate on that? Thank you very much for this one.
You are welcome. Thank you for watching and your good follow-up questions. Sure, The foldback feature I-V plot is shown starting at minute 25:46 . In summary BJT Transistor T3 is off during nominal operation of this foldback regulator. As soon as the output current reaches the max allowed one Amp the voltage at the T1 Darlington transistor emitter (Ve1) reaches nearly 10+2.05*1 = 12.05 volts. Then the T3 Base voltage becomes R2/(R1+R2)*12.05v = 0.88 *12.05 = 10.6 volt =Vb3 while Ve3 = Vout = 10 volt. Therefore Base-Emitter voltage of BJT Transistor T3 is Vbe3 = Vb3 - Ve3 = 10.6 -10 = 0.6 volt which is the onset threshold to turn on the T3 transistor that then draws current from the base of Darlington pair and hence limits the output current. If Resistor Load RL is further reduced, the foldback feature would not allow more output current (beyond max 1 Amp) and hence the output voltage starts dropping because Vout = RL * Iout and hence as RL is further reduced beyond this point, the Vout is linearly reduced as well and ultimately when RL=0 (shorting the output to ground), the output current is limited to 1/3 Amp (as designed and discussed in the video) so that Darlington BJT power consumption is limited to VCE*Icollector = 15v*1/3A = 5 Watts (which is the design target in this voltage regulator design example). This foldback feature is plotted near the end of the video. For more examples please see: Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html Voltage regulator design without Op Amp ua-cam.com/video/ArisQp7V0Ac/v-deo.html Voltage Regulator design with Op Amp BJT JFET and Zener Diodes ua-cam.com/video/CJl-urzeiTo/v-deo.html I hope this explanation and these further examples are helpful. 🙂
You are welcome. Glad to hear the explanation is helpful. The reason, as a design target. We are concerned about Darlington BJT power consumption is because we don't want to burn that transistor (and hence the regulator) due to applying too small load at the output of the circuit. The main job of the voltage regulator is providing a constant stable 10 volt at the output as long as the drawn current is less than the level that is not safe for the main power transistor (which is the Darlington Bipolar Junction Transistir Pair). I hope this is helpful regarding your question about power consumption. 🙋♂️
Thanks for watching and comment. Glad that you liked this video and it is useful. For more Op Amp Circuits and Regulator examples please see: Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these circuit videos are useful as well. 🙏
Thanks for your interest in my channel and for your follow-up question. I'd love to simulate if I get the chance (which I rarely do). Please surely share your observations if you get the chance to simulate the circuit. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html Universal Analog Filter Design ua-cam.com/video/2J-0msXZE2o/v-deo.html Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html Analog Computer to Raise Signal to power n ua-cam.com/video/IUTlBH1UraE/v-deo.html And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these circuit videos are interesting as well.
Two negative points of this circuit. 1. Very high voltage drop. Total V drop = V drop Darlington pair + V drop Op-Amp + V drop R current sense which can easily exceed 2V. 2. Not sure it even works as all extra current will flow thru the Op-Amp and T3 at the point of burning the Op-Amp. There will be no real limiting factor as The Op-amp will try to compensate for voltage drop.
Thanks for watching & sharing your thoughts. Please see Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html as a better example. 1) The circuit is designed to generate stable output 10 volt for the resistor load RL . Input supply voltage is unregulated and varies in a wide range (for example 14-20 volt range). So we need to consider the lowest and highest values of unregulated input supply to make sure design works for both. 2) OpAmp Output current is minimal. It's on the order of 1mA during nominal operation when T3 is off. When regulator output current reaches max allowed value of 1 Amp then T3 turns on and starts drawing minimal current from op Amp output so that the current going to the base of Darlington transistor will always remain less than 1 mA. For more Regulators & Op Amp Circuit examples please see ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope this is helpful. Thanks for watching 🙋♂
Thanks Steven for watching, your interest and your feedback. Glad that you like my channel. Sure, I will improve audio in next videos posted in ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html Thanks again.
Thanks for watching, your interest, insightful comments & feedback. Please NEGLECT 11-15v assumption for input supply range. DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as Darlington Transistor power consumption is below the maximum allowed. The current foldback feature kicks in otherwise to limit the output current. For more Op Amp Circuits and Regulator examples please see: Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Temperature-Independent Current Circuit Design with Op Amp, BJT, Zener, Schottky Diodes ua-cam.com/video/hFbnjbddUvs/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
How to find Bode Plot, Freq Response, Transfer Function of Analog Filters ua-cam.com/video/vZFkPeDa1H8/v-deo.html
Universal Analog Filter Design ua-cam.com/video/2J-0msXZE2o/v-deo.html
Laplace Transform Example and S-domain circuit analysis: ua-cam.com/video/ps8N5TPM_qU/v-deo.html
Op Amp circuit Bode Frequency plot ua-cam.com/video/BLVzuuqAlZs/v-deo.html
Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html
Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html
Analog Computer to Raise Signal to power n ua-cam.com/video/IUTlBH1UraE/v-deo.html
Triangle Oscillator Op Amp circuit ua-cam.com/video/JF5Up_cuL9k/v-deo.html
Differential Equation Solver Analog Circuit ua-cam.com/video/R3X5AYNZGEI/v-deo.html
Complex Sinusoid Oscillator ua-cam.com/video/GXRhmwmS5Zk/v-deo.html
Sawtooth Oscillator Design ua-cam.com/video/2eUsGPfqbW4/v-deo.html
Full-Wave Rectifier circuit example ua-cam.com/video/DJJMNU-CYcg/v-deo.html
Sawtooth Waveform Generator design with OpAmp, JFET, BJT ua-cam.com/video/5zHXTx-Vl20/v-deo.html
op amps Circuit with feedback loops to design an analog computer that solves a second order differential equation ua-cam.com/video/HeZRtnRXpEI/v-deo.html
For more analog circuits and signal processing examples see: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these Circuit design and analysis videos are helpful. 🙋♂
Very good. A simulation in LTSPICE Would be nice
Thank you. Glad that you liked this video. For more examples please see:
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
Voltage regulator design without Op Amp ua-cam.com/video/ArisQp7V0Ac/v-deo.html
Voltage Regulator design with Op Amp BJT JFET and Zener Diodes ua-cam.com/video/CJl-urzeiTo/v-deo.html
I hope these additional examples are interesting. 🙋♂️
Love your videos. Correct me if I’m wrong but when you are supplying the positive rail of the operational amplifier 11V you can’t regulate Vout because you need 2VBE + Vout > 11V at the output of the op-amp.
Thanks Marcos for watching, your encouraging comment and good question. Glad that you like my videos 🙂 It is always important to double-check BJT Collector-Emitter voltage requirements. Please NEGLECT 11-15v assumption for input supply range. Our DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For another example please see Voltage Regulator Design with Op Amp and BJT ua-cam.com/video/rI9f6-DyXxQ/v-deo.html . I hope this is helpful. Thanks again for your interest & follow-up comment. 🙋♂️
@@STEMprof I'm sorry, but you're wrong. At the max current (1 A) and nominal Vout (10 V), the VCE of the MJE will be over 3 V, while the VBE of the same transistor will be over 2 V (page 2 of the component datasheet). Then you have to add even the drop on sensing resistor that is over 2 V too. So, the minimum supply voltage has to be the greater than (10 + 2 + 3) V = 15 V. Another flaw is when you say that the power dissipated by the sensing resistor is negligible in the calculation of the power dissipated by T1: it is not. At 1 A of load current, the transistor dissipates 1 A x (15 - 10 - 2) V = 3 W, while the sensing resistor dissipates 1 A x 2 V = 2 W: they are almost the same. A revision is needed.
@@giorgiocanal1659Thanks Giorgio for watching, your detailed attention & insightful feedback. You have a good point. Pls NEGLECT 11-15v assumption for input supply range. DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For more Op Amp Circuits and Regulator examples please see:
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
AbdcAnalog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
Thanks again. I appreciate your attention and feedback. 🙋♂
@marcos010697 Thanks again Marcos for your detailed attention & insightful feedback. You have a good point. Please NEGLECT the 11-15v assumption for input supply range. Our DESIGN GOALs are: MAX Darlington POWER target is 5W, & Output regulated voltage is 10V as long as max Darlington Transistor power is sustained. The current foldback feature kicks in otherwise to limit the output current. I will post another example soon specifically for 11-15v input supply range. For more Op Amp Circuits and Regulator examples please see:
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
Thank you again. I appreciate your attention and feedback. 🙏👍
I think you need a resistor at the output of your opamp. Opamps are voltage devices and their output have ideally zero resistance. You cannot pull down the current through T3. However, real opams have about 100 ohm output resistance.
Thanks for watching and sharing your thoughts and practical suggestions. This example relies on the fact that a reasonably selected Op Amp has few hundred ohm output resistance and say 10-20 mA max output Op Amp current that is usually specified in Op Amp datasheet. In such case BJT transistor T3 is able to redirect current to limit the output current. Nonetheless, it is a good practice to have a reasonable resistor (say few hundred ohm to 1 kilo ohm) in series at the output of operational amplifier. (Side note: there are different types of operational amplifiers including transconductance op amps that deliver currents at the output). For more op amp circuits please see ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope this clarification and further examples are helpful. Thanks again 🙏
Thank you for video
You are welcome. Thanks for watching. Glad that this video is helpful. For more Op Amp Circuits and Regulator examples please see:
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these circuit videos are interesting as well.
Awesome as always. I am trying to describe how T3 works. T3 normally in many designs just senses the voltage drop in the shunt resistor (r in this case) until this reaches 0.6v, but now the base is tied to a node (between R1 and R2) and is not sensing the current proportional any more. T3 now has information from Imax and Vo at the same time(eq.1)? maybe that is why is called "current foldback"?. Thank you a lot, my friend!
You're welcome. Thanks for watching and your good questions. BJT Transistor T3 is off during nominal operation of this foldback regulator. As soon as the output current reaches the max allowed one Amp the voltage at the T1 Darlington transistor emitter (Ve1) reaches nearly 10+2.05*1 = 12.05 volts. Then the T3 Base voltage becomes R2/(R1+R2)*12.05v = 0.88 *12.05 = 10.6 volt =Vb3 while Ve3 = Vout = 10 volt. Therefore Base-Emitter voltage of BJT Transistor T3 is Vbe3 = Vb3 - Ve3 = 10.6 -10 = 0.6 volt which is the onset threshold to turn on the T3 transistor that then draws current from the base of Darlington pair and hence limits the output current. For more Op Amp Circuits please see:
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html
And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope this explanation and these circuit videos are helpful. 🙏
Again, I greatly enjoyed your analysis, since this is new to me. In the past, I could do a simple analysis of transistor-based circuits without feedback. With the feedback, it is a little more involved. It would be helpful if you could explain how the circuit would respond along the whole range of loads, not just two boundary cases. Also, I am confused about your usage of the "power" of the regulator (power supply). I would expect that we are talking about max power that could be delivered to the load, not dissipated in some internal circuitry, such as a pass transistor. Could you elaborate on that? Thank you very much for this one.
You are welcome. Thank you for watching and your good follow-up questions. Sure, The foldback feature I-V plot is shown starting at minute 25:46 . In summary BJT Transistor T3 is off during nominal operation of this foldback regulator. As soon as the output current reaches the max allowed one Amp the voltage at the T1 Darlington transistor emitter (Ve1) reaches nearly 10+2.05*1 = 12.05 volts. Then the T3 Base voltage becomes R2/(R1+R2)*12.05v = 0.88 *12.05 = 10.6 volt =Vb3 while Ve3 = Vout = 10 volt. Therefore Base-Emitter voltage of BJT Transistor T3 is Vbe3 = Vb3 - Ve3 = 10.6 -10 = 0.6 volt which is the onset threshold to turn on the T3 transistor that then draws current from the base of Darlington pair and hence limits the output current. If Resistor Load RL is further reduced, the foldback feature would not allow more output current (beyond max 1 Amp) and hence the output voltage starts dropping because Vout = RL * Iout and hence as RL is further reduced beyond this point, the Vout is linearly reduced as well and ultimately when RL=0 (shorting the output to ground), the output current is limited to 1/3 Amp (as designed and discussed in the video) so that Darlington BJT power consumption is limited to VCE*Icollector = 15v*1/3A = 5 Watts (which is the design target in this voltage regulator design example). This foldback feature is plotted near the end of the video. For more examples please see:
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
Voltage regulator design without Op Amp ua-cam.com/video/ArisQp7V0Ac/v-deo.html
Voltage Regulator design with Op Amp BJT JFET and Zener Diodes ua-cam.com/video/CJl-urzeiTo/v-deo.html
I hope this explanation and these further examples are helpful. 🙂
@@STEMprof Thank you very much, that is helpful, indeed.
You are welcome. Glad to hear the explanation is helpful. The reason, as a design target. We are concerned about Darlington BJT power consumption is because we don't want to burn that transistor (and hence the regulator) due to applying too small load at the output of the circuit. The main job of the voltage regulator is providing a constant stable 10 volt at the output as long as the drawn current is less than the level that is not safe for the main power transistor (which is the Darlington Bipolar Junction Transistir Pair). I hope this is helpful regarding your question about power consumption. 🙋♂️
great video, can built the circuit and show us how it works
Thanks for watching and comment. Glad that you liked this video and it is useful. For more Op Amp Circuits and Regulator examples please see:
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html
And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these circuit videos are useful as well. 🙏
Good morning...
Is it possible to simulate your design in TINA T software from texas instruments ?
Thanks for your interest in my channel and for your follow-up question. I'd love to simulate if I get the chance (which I rarely do). Please surely share your observations if you get the chance to simulate the circuit. For more Op Amp Circuits and Regulator examples please see:
Op Amp Amplifier with Electronic Gain Control ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html
Universal Analog Filter Design ua-cam.com/video/2J-0msXZE2o/v-deo.html
Analog Logarithm Computer ua-cam.com/video/RpKEq5WyoLg/v-deo.html
Lowpass Butterworth Filter: ua-cam.com/video/UzCjkwqy-9w/v-deo.html
Analog Computer to Raise Signal to power n ua-cam.com/video/IUTlBH1UraE/v-deo.html
And Analog circuits and signal processing playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these circuit videos are interesting as well.
Two negative points of this circuit.
1. Very high voltage drop. Total V drop = V drop Darlington pair + V drop Op-Amp + V drop R current sense which can easily exceed 2V.
2. Not sure it even works as all extra current will flow thru the Op-Amp and T3 at the point of burning the Op-Amp. There will be no real limiting factor as The Op-amp will try to compensate for voltage drop.
Thanks for watching & sharing your thoughts. Please see Voltage Regulator Design with Op Amp and BJT Transistor ua-cam.com/video/rI9f6-DyXxQ/v-deo.html as a better example.
1) The circuit is designed to generate stable output 10 volt for the resistor load RL . Input supply voltage is unregulated and varies in a wide range (for example 14-20 volt range). So we need to consider the lowest and highest values of unregulated input supply to make sure design works for both.
2) OpAmp Output current is minimal. It's on the order of 1mA during nominal operation when T3 is off. When regulator output current reaches max allowed value of 1 Amp then T3 turns on and starts drawing minimal current from op Amp output so that the current going to the base of Darlington transistor will always remain less than 1 mA. For more Regulators & Op Amp Circuit examples please see ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope this is helpful. Thanks for watching 🙋♂
I love your channel, but please please get a better microphone it has very high and painful "S" problem.
Thanks Steven for watching, your interest and your feedback. Glad that you like my channel. Sure, I will improve audio in next videos posted in ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
Thanks again.