Thanks for watching. For more examples please see: Op Amp Amplifier with Electronic Gain Control: How does it work? kzitem.info/news/bejne/r6WEzYWmm5xoao4 Instrumentation Amplifier with Electronic Gain Control kzitem.info/news/bejne/pGqqzZyQZqNnjag Power Amplifier Design (Class A) with Transformer kzitem.info/news/bejne/yIGisKangKOWdn4 VCA Electronic Gain Control (Part 1): Voltage-Controlled Attenuator Overview kzitem.info/news/bejne/xHywv46piXelg2U Analog Multiplier Circuit kzitem.info/news/bejne/t4ZrmXVos6KHgIY Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors kzitem.info/news/bejne/mXh84KefcF-Hlag Thermometer Circuit Design with Op Amp & BJT transistor kzitem.info/news/bejne/lmuP2aaXf3dhpZw Analog Vector Summer Circuit Design with Op Amp and BJT Transistors kzitem.info/news/bejne/sX932ZVmioCHoag Op Amp Analog Computer Differential Equation Solver kzitem.info/news/bejne/poSnmW17nqWXg6w Push-Pull Power Amplifier with Darlington Transistors kzitem.info/news/bejne/mWxss42fm6FprHo Sallen-Key Analog Filter Design Tutorial kzitem.info/news/bejne/rK2L1IWOm51omoI For more analog circuits and signal processing examples see the Analog Circuits Video playlist: kzitem.info/door/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these Circuit design and analysis videos are interesting and useful. 🙋♂
@sc0or
8 ай бұрын
A greatness of this schematic is that you can use a linear potentiometer and get a log scale attenuation. A very demanded feature for an audio amp
@STEMprof
8 ай бұрын
Thanks for highlighting the log scale attenuation using single linear Potentiometer and single op amp. To your good point, Another example of adjustable Attenuator circuit for audio signal processing applications is the VCA voltage-controlled Attenuator discussed in kzitem.info/news/bejne/xHywv46piXelg2U
@hintoninstruments2369
6 ай бұрын
You don't get a log scale attenuation, just a wide range. The logs are in the dB calculation, not the circuit. Nobody said anything about the distribution of the gain with pot position or the noise gain. Similar circuits are use for audio trimming by connecting the pot wiper to the inverting input which gives symmetrical gain/attenuation with 0dB in the centre and only noise gain with signal gain.
@STEMprof
5 ай бұрын
@@hintoninstruments2369 Thanks for watching and sharing your thoughts. As you noted, this circuit is presented as an interesting minimal design example to achieve a very wide gain/attenuation range using just one op amp, one Potentiometer & few resistors. The Gain has a nonlinear relationship with the wiper position.
@Chupacabras222
8 ай бұрын
These are very valuable videos here on youtube.
@STEMprof
8 ай бұрын
Thank you for encouraging comment. Glad that my videos are useful. Btw, given that there are nearly 200 videos in my Analog & electronic circuits playlist, is it easy to search for specific topic among those 200 videos?
@samamani5423
4 ай бұрын
hi really appreciate your videos helped me learn a lot . i'm in a predicament designing a similar circuit . my specification : Input +-10Vac or +-5Vac or 3.3Vac / 50Mhz . Output:+-.5Vac / 50Mhz , which equals to , respectively to 1/20 gain = 0.05 = -26.02dB for +-10Vac and 1/10 gain = .1 = -20dB for +-5Vac and 1/6.6 gain = .1515 = -16.39 for +-3.3Vac input signal . i really prefer to achieve this with FDA configuration but single-ended I/O op amp would suffice . i have many issues finding a circuit capable of this requirements . 1- your design for achieving -25dB inputs 1/101 of the input signal into op-amp . 2- i cannot find a find an op-amp with a reliable spice model to simulate this setup before designing and every simulation attempt is failed so far 3- output noise on the opamps is very reliant on the Rf value , extracting this value from datasheet and employing it in simulation software produces a very different output than expected .. 4- i'm having a hard time finding suitable op amp for this task i would really appreciate if you could help me to find solution for these problems , btw i'm designing this as an ADC Driver and also i'm using proteus for simulation .
@STEMprof
4 ай бұрын
You're welcome Sam. Glad that my channel is useful. Regarding the choice of Op Amp, as discussed in minute 18:00 in this video, I suggest CMOS low-noise op amps from Texas Instruments of Analog Devices with zero or near zero offsets and very low drift. I also suggest a decent slew rate which of course depends on the maximum input frequency in your applications. Also see the Texas Instruments Op Amp used in kzitem.info/news/bejne/qY-nsYVjp4eXaKQ video. Alternatively, you might consider TI FET-input TLV9301 Op Amp or more expensive TI LMH6714 for higher frequency (say video applications). I hope this is helpful.
@samamani5423
4 ай бұрын
@@STEMprof thanks for your help .
@zaikindenis1775
8 ай бұрын
Thank you for video. Seems like input impedance will vary with the gain.
@STEMprof
8 ай бұрын
You are welcome. Thanks for sharing your thoughts. While you are right that input impedance changes as we adjust the Potentiometer, the input impedance has the minimum of R1 (4.7kOhm in this example) and the maximum of R1+10 kOhm (14.7 kOhm ) meaning the change is not substantial (not orders of magnitude). If need be, We can also further decrease dynamic range of input impedance by increasing the value of R1. An alternative method is discussed in Another technique is discussed in Op Amp Amplifier with high input impedance and large voltage gain kzitem.info/news/bejne/y6ifwKhniIRmgqA . I hope this is helpful. For more examples please see my Analog & Op Amp Circuit Videos playlist kzitem.info/door/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt
@Parirash123
8 ай бұрын
Input impedance variation is inevitable. May be you can cascade a Commom-collector stage on 'Vin' to have almost constant input impedance.
@STEMprof
8 ай бұрын
@@Parirash123 thanks for sharing your thoughts and your design suggestion. Another technique is discussed in Op Amp Amplifier with high input impedance and large voltage gain kzitem.info/news/bejne/y6ifwKhniIRmgqA Ultimately, if constant and very large input impedance is required in a given design, Maybe just adding a buffer stage op amp at input is the safest way to satisfy such absolute requirement. This is illustrated in the video of Instrumentation Amplifier with Electronic Gain Control kzitem.info/news/bejne/pGqqzZyQZqNnjag . I hope this is helpful.
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