Yes and this circuit is not designed to pass high frequencies so it's not a surprise that the square wave has overshoot. He should also do a bode plot of the frequency response.
Really cool project ... I would have never imagined ... clever HP-ish technique. Would love to see a sine wave and some frequency testing; but I can do that when I build one myself :-)
Some time ago, I took over a modular battery management system that used 4 optocouples to charge a capacitor from a Li Ion battery and then connect it to an isolated microcontroller to measure. It didn't work great, and I'm amazed it worked as well as it did.
I forgot to mention, that the spikes you are unable to compensate in the case of the square wave may be due to the bandwidth limitation of the opamp. I think of this because the LED will turn on fast, and so will the phototransistor, but I have doubts about the slewrate of the OPAMP
sunfire used a optocoupler to isolated the analog audio signal from the input board to the preamp as the whole internal circuitry was live to get rid of the big heavy transformer and just run the power amp straight from 110v mains. but still had the rca inputs galvanically isolated. he didnt use a dual optocoupler but one that has its Base pin broken out to set some sort of pre-bias. well yea it only needed to go up to 150..200hz anyways. they put like 15mA onto the led and modulated the signal +-5mA onto it or something
It would be very cool to have a stereo version🧐. Will be great alternative to the audio transformers I'm currently using to get rid of ground loop hum on long cable runs
Cool project. I found that a couple years back when trying to answer a "how illI do this". iirc it was called servoing a optiocoupler. I also made the assumption that digitizing it and shipping it over fiber would be the correct answer, but I had lots of problems finding the parts ( TX, RX, fiber) I finally thought maybe it would be done with signal transformers for the data. But I dislike that idea for a few reasons. This is for a DC load project I'm halfway through the mental process designing. It's still suffering feature creep like building as modules that could be put in series or parallel keeps coming up, but needs to do 500W and 1000V. I already got 4 mosfets for the job IXFK52N100X. If you have any fiber optic link insights, I would love to hear them.
RY2 potentiometer doesn't set LED Current ! Current must satisfy feedback loop. It regulates opamp output voltage, and indeed - may influence overshoot. And input voltage range.
On the contrary, it looks as it has too little phase margin, which will usually cause peaking. I hope IMSAIGuy reads this, because I believe that the peaking can be reduced by increasing the capacitor across the op amp feedback. The peaking is most likely cause by phase delay through the two optos due to there somewhat slow response, resulting in an overshoot from the opamp "being too fast" ( in reality having gain where there is little phase margin left)
Thanks for this project, it might help out with some stuff I've been tinkering with. The response look linear, but it is still inverted or does the opamp on the input invert the input signal so that it comes out correctly? Would love to see if this can handle an NTSC video signal.
Really enjoy this linearity demonstration. Perhaps, I don't remember, you covered this, but as I am tinkering a bit with audio stuff, did you measure below 10% of the bandwith of the opamps? It seems to b e a general rule to pick an opamp that has a bandwith of at least ten times the desired bandwith, in order to keep distortion away. But it's quite a science, those opamps ;)
Would your try a audio "AGR", Automatic Gain Reduction with that optocoupler PC817 or H11 opto Fet? To see what it takes to achieve something like: Teletronix LA-A2 Opto Compressor accept the 290 Volts.
I wonder what will happen if the second opto (U4) was also straddling the gap but the other way round (LED to the right) and the feed back was gathered from the output of U3A and fed across the gap to the first opamp U1A. Then you would have a composite setup where the feedback was global from the very last output back to the first input. In this first form anything the happens in the HV side does not get reported back or I should say 'Fed' back. Any noise created in the HV side does not get treated in the LV side. This is purely a thought and probably of no interest to anyone so please 'Commentators' don't get on my case :)......cheers.
Thanks for sharing your work can you help me to make circuit schematics and code I want to read voltage with an isolated ground Mine setup is 4x 12v battery and 4x simple solar controllers Aliexpress Every battery have the own Solar controller I use the Esp32 and 1x ADS1115 ADS1115 is a 16-bit, 860-SPS, 4-channel, delta-sigma ADC with PGA, oscillator, VREF, comparator and I2C. I use voltage divider 4x 6.44K 1% and 30K 1% The Solar controllers have switched ground if i connect the ground together i get errors The controllers are good it is charging the Batterys good.
OH NO! He did it again! The rubbish circuit with two optocouplers! WHY? This is pointless in 2024! Use the standard IL300 circuit and be good! And a reflow over for a handfull of SMT components? C'mon! Heat your circuit with hot air to maybe 60-70°C an see it drift!
Haha, yes. But for an educational circuit, you can't beat its universality: almost everyone has at least a couple of PC817 optocouplers salvaged from SMPS's!.
This is an educational channel and not an engineering challenge game show. You realy do seem to have missed the point of this circuit and it's purpose :)
Looks great. It might be interesting to pass a sine wave and measure THD at the output and compare it with THD at the input.
Yes and this circuit is not designed to pass high frequencies so it's not a surprise that the square wave has overshoot.
He should also do a bode plot of the frequency response.
@@cmuller1441 I'd think we should see Gibb's phenomena then, which this doesn't look like.
That is a neat circuit. Using a second optocoupler and the feedback of the op amp to correct the signal. Really neat.
Really cool project ... I would have never imagined ... clever HP-ish technique. Would love to see a sine wave and some frequency testing; but I can do that when I build one myself :-)
Some time ago, I took over a modular battery management system that used 4 optocouples to charge a capacitor from a Li Ion battery and then connect it to an isolated microcontroller to measure. It didn't work great, and I'm amazed it worked as well as it did.
Sony had a TV monitor that used an optocoupler for video and another one for audio, back in the day.
Add a small amount of dc offset to your square wave and you should remove the undershoot.
I forgot to mention, that the spikes you are unable to compensate in the case of the square wave may be due to the bandwidth limitation of the opamp. I think of this because the LED will turn on fast, and so will the phototransistor, but I have doubts about the slewrate of the OPAMP
Wow you are amazing! Hopefuly this channel can develop my passion for electrical engineering
sunfire used a optocoupler to isolated the analog audio signal from the input board to the preamp as the whole internal circuitry was live to get rid of the big heavy transformer and just run the power amp straight from 110v mains. but still had the rca inputs galvanically isolated.
he didnt use a dual optocoupler but one that has its Base pin broken out to set some sort of pre-bias. well yea it only needed to go up to 150..200hz anyways.
they put like 15mA onto the led and modulated the signal +-5mA onto it or something
It would be very cool to have a stereo version🧐. Will be great alternative to the audio transformers I'm currently using to get rid of ground loop hum on long cable runs
just use two
Cool project. I found that a couple years back when trying to answer a "how illI do this". iirc it was called servoing a optiocoupler. I also made the assumption that digitizing it and shipping it over fiber would be the correct answer, but I had lots of problems finding the parts ( TX, RX, fiber) I finally thought maybe it would be done with signal transformers for the data. But I dislike that idea for a few reasons. This is for a DC load project I'm halfway through the mental process designing. It's still suffering feature creep like building as modules that could be put in series or parallel keeps coming up, but needs to do 500W and 1000V. I already got 4 mosfets for the job IXFK52N100X. If you have any fiber optic link insights, I would love to hear them.
Why triangular only? Can you show us DC accuracy?
It will be useful for sensor and analog signal isolation.
RY2 potentiometer doesn't set LED Current ! Current must satisfy feedback loop.
It regulates opamp output voltage, and indeed - may influence overshoot.
And input voltage range.
Would it be practical to reduce the feedback decoupling capacitor? That might be the cause of the undershoot.
On the contrary, it looks as it has too little phase margin, which will usually cause peaking.
I hope IMSAIGuy reads this, because I believe that the peaking can be reduced by increasing the capacitor across the op amp feedback.
The peaking is most likely cause by phase delay through the two optos due to there somewhat slow response, resulting in an overshoot from the opamp "being too fast" ( in reality having gain where there is little phase margin left)
Thanks for this project, it might help out with some stuff I've been tinkering with. The response look linear, but it is still inverted or does the opamp on the input invert the input signal so that it comes out correctly? Would love to see if this can handle an NTSC video signal.
I like your IR reflow oven !!
The IL-300 / IL300 is better (than two PC817s), and is much higher bandwidth (at least 10x).
Really enjoy this linearity demonstration. Perhaps, I don't remember, you covered this, but as I am tinkering a bit with audio stuff, did you measure below 10% of the bandwith of the opamps? It seems to b e a general rule to pick an opamp that has a bandwith of at least ten times the desired bandwith, in order to keep distortion away. But it's quite a science, those opamps ;)
Would your try a audio "AGR", Automatic Gain Reduction with that optocoupler PC817 or H11 opto Fet?
To see what it takes to achieve something like: Teletronix LA-A2 Opto Compressor accept the 290 Volts.
Would something like this work with a composite video signal?
I wonder what will happen if the second opto (U4) was also straddling the gap but the other way round (LED to the right) and the feed back was gathered from the output of U3A and fed across the gap to the first opamp U1A. Then you would have a composite setup where the feedback was global from the very last output back to the first input. In this first form anything the happens in the HV side does not get reported back or I should say 'Fed' back. Any noise created in the HV side does not get treated in the LV side. This is purely a thought and probably of no interest to anyone so please 'Commentators' don't get on my case :)......cheers.
that would be great but you are using a non-linear device to feed back from a non-linear device.
a composite setup comes to mind
@@IMSAIGuy Thanks, nearly bedtime for me but I will give it some thought, thanks again for replying :)
I had this thought also but assumed there was a good reason it wasn’t done that way.
@@mikebond6328 Yes I'm struggling to understand but Very Kind IMSAI Guy gave me a thought to think about tommorow ! thanks for your comment :)
Thanks for sharing your work
can you help me to make circuit schematics and code
I want to read voltage with an isolated ground
Mine setup is 4x 12v battery and 4x simple solar controllers Aliexpress
Every battery have the own Solar controller
I use the Esp32 and 1x ADS1115
ADS1115 is a 16-bit, 860-SPS, 4-channel, delta-sigma ADC with PGA, oscillator, VREF, comparator and I2C.
I use voltage divider 4x 6.44K 1% and 30K 1%
The Solar controllers have switched ground if i connect the ground together i get errors
The controllers are good it is charging the Batterys good.
Found it!!!
Nice! How about trying PCBway assembly service? It's very cheap and will save you a lot of time.
OH NO! He did it again! The rubbish circuit with two optocouplers! WHY? This is pointless in 2024! Use the standard IL300 circuit and be good! And a reflow over for a handfull of SMT components? C'mon! Heat your circuit with hot air to maybe 60-70°C an see it drift!
Haha, yes. But for an educational circuit, you can't beat its universality: almost everyone has at least a couple of PC817 optocouplers salvaged from SMPS's!.
This is an educational channel and not an engineering challenge game show. You realy do seem to have missed the point of this circuit and it's purpose :)
@@andymouse Nobody is useless. He can still be a bad example.
thanks for the part number, i will get some to test.
Congratulations.
It works... !!!