To make a peak detector, feed the input sine wave into an integrator or differentiator with an RC network and a 741 op amp. The integral or derivative of a sine wave is a 90-deg shifted sine wave. Then the zero-crossings and peaks are interchanged. Feed that sine wave into an optocoupler. The zero-crossing detection becomes peak detection of the original waveform.
Hi Lewis, thank you for sharing this! Is there a way to detect current angle with similar circuit? I am trying a way to calculate the difference between voltage angle and current angle. Thanks!
Good video one question, in the H11AA1 opto {start of video} why are the back to back leds only producing light on the ‘ac’ side when the polarity crosses zero to swap polarity? Should they not be producing light and thus switching the base in the other side continually?
Instead of adjusting AC power by phase angle, since you have a programmable microcontroller, why not just switch on integral cycles? EG for 33percent power, turn on the triac for one complete cycle and skip the next two. This in gentler on the load and I expect less transients and EMI. For something like 73percent, a hardcoded sequence to distribute the offs and ons evenly will be required but surely no big deal to code. You can do away with the pot and just have two buttons to increment or decrement the power from 0,1,2 until 99,100 percent.
If i am firing an independent led optoisolator, it counts the cycles from the main supply going to the SCR's by a separate wire I would connect to the arduino?
Lewis Loflin It took a minute, but I understand now. You explain it perfectly. I was still wrapping my head around the schematic and it clicked finally. Thank you for the videos and great website. Now I need to research how the code works to manipulate it for my application. Andrew
Great video. Thanks. It was very helpful (like all your others). Do you have any thoughts on the following… Soon I will need a system that will detect 10^6 blue photons from a 10 usec pulse of light. I was planning to use a Silicon Photo Multiplier (SiPM), perhaps SensL’s C-30035. Any thoughts, suggestions or insights would be helpful?
Hi Lewis, will the H1AA1 circuit for ZCD work with 220VAC ? Also, can we call this circuit "isolated" from controls circuit given the isolation is only the optocoupler and not a transformers which is the stardard practice ?
i want speed control not on the resistor on arduino R3 .... but i have written an app to import PWM on it and then send it down to esp8266 .. can i connect esp8266 to arduino via uart .... I'm afraid the UART code is delayed
I assume the dual reverse alignment is to compensate for both polarity in the ‘ac’ but why are they only in a light functional state at the swap of polarity?
Yes obviously. The input is a pwm which is modulated over an ac signal i think. I want to know how the MPDMv4 universal dimmer works. It uses just a pwm input and no zero cross input which is processed internally.
This circuit doesn't work because the LED only turns on when about 10mA flows and this is when 24x1.41 sin(wt) =22 and this is for wt around 40 degrees which is well above zero detects. Did you test this circuit?
24VAC has a peak voltage of 1.41 X 24 =~ 36V. - 36 / 2200 = 16mA. Put an oscilloscope on the optocoupler transistor collector and see if you have a pulse then get back to me. The optocoupler is more sensitive than you think. If you have substituted the optocoupler then simply lower the 2.2k to say 1.5k or even 1k. Look at the spec sheet and you will find some can take up to 60mA.
Hello. With zero cross detection AC regulator I would like to control welding transformer, but I saw at the scope that for example at 50% switch the transformer always will get the maximum voltage at turning on. It would be better to turn on at 0V and turn off at some point not vice versa. Can you please help how could I do that?
You are not dealing with DC. An AC voltage is often an average known as RMS - DC equivalent. The longer the voltage is turned on the more power delivered to the load.
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It was awesome Mr.Lewis Loflin thank you for such a brief explanation.
This is the best video I've found on the subject. Just subscribed. Thanks!
Awesome circuit and explanation. Good Job
More than what i was looking for. Very simplified circuit of the ZCD
Thanks!
Thank you Lewis. I enjoyed watching.
Main webpage:
www.bristolwatch.com/ele2/zero_crossing.htm
thank you for the use case applications! very useful information
To make a peak detector, feed the input sine wave into an integrator or differentiator with an RC network and a 741 op amp. The integral or derivative of a sine wave is a 90-deg shifted sine wave. Then the zero-crossings and peaks are interchanged. Feed that sine wave into an optocoupler. The zero-crossing detection becomes peak detection of the original waveform.
This works just fine and construction is easier.
Congratulation Sir. Your hardware it's really good. Thank you. Best regards
Hi Lewis, thank you for sharing this!
Is there a way to detect current angle with similar circuit? I am trying a way to calculate the difference between voltage angle and current angle. Thanks!
THANK YOU ! YOU ARE AWESOME
do you have a diagram to show how the probes of the Oscilloscope are connected to display what you have.
Good video one question, in the H11AA1 opto {start of video} why are the back to back leds only producing light on the ‘ac’ side when the polarity crosses zero to swap polarity? Should they not be producing light and thus switching the base in the other side continually?
Thank you,well explained
Great video
Hi, congratulation nice video, question how you are connecting the oscilloscope
awesome! thanks a lot!!
Instead of adjusting AC power by phase angle, since you have a programmable microcontroller, why not just switch on integral cycles? EG for 33percent power, turn on the triac for one complete cycle and skip the next two. This in gentler on the load and I expect less transients and EMI. For something like 73percent, a hardcoded sequence to distribute the offs and ons evenly will be required but surely no big deal to code. You can do away with the pot and just have two buttons to increment or decrement the power from 0,1,2 until 99,100 percent.
Because that is more complex and the control is poor. Thanks.
THANKS!
If i am firing an independent led optoisolator, it counts the cycles from the main supply going to the SCR's by a separate wire I would connect to the arduino?
Don't know what you mean. Arduino gets the pulses and it fires the SCR.
Lewis Loflin It took a minute, but I understand now. You explain it perfectly. I was still wrapping my head around the schematic and it clicked finally. Thank you for the videos and great website. Now I need to research how the code works to manipulate it for my application.
Andrew
Good luck.
Great video. Thanks. It was very helpful (like all your others).
Do you have any thoughts on the following…
Soon I will need a system that will detect 10^6 blue photons from a 10 usec pulse of light.
I was planning to use a Silicon Photo Multiplier (SiPM), perhaps SensL’s C-30035.
Any thoughts, suggestions or insights would be helpful?
Hi Lewis, will the H1AA1 circuit for ZCD work with 220VAC ? Also, can we call this circuit "isolated" from controls circuit given the isolation is only the optocoupler and not a transformers which is the stardard practice ?
Use a larger input resistor.
Hello, Would you have the arduino code for this? Thanks.
i want speed control not on the resistor on arduino R3 .... but i have written an app to import PWM on it and then send it down to esp8266 .. can i connect esp8266 to arduino via uart .... I'm afraid the UART code is delayed
Is there any advantage in using a rectifier with single LED optocoupler, compared to the double LED AC optocoupler.
I assume the dual reverse alignment is to compensate for both polarity in the ‘ac’ but why are they only in a light functional state at the swap of polarity?
thankyou !
Thq soomuch ❤
How to 220v led switch off with use of ac dimmer controller
What about if you do not use the zero-crossing detector, will it randomly trigger the phase angle control?
Yes that is the problem.
Sir can u teach how to build an zero crossing detector circuit using arduino and its coding too
Go here: www.bristolwatch.com/ele2/zero_crossing.htm
This is related to Arduino power control here is a video:
th-cam.com/video/gnlcS_xOp9k/w-d-xo.html
AC Power Control with Arduino
Merci.
please after rectifying the 12v can the optocoupler sees zero volt?
Yes, it is pulsating DC, don't use a filter cap.
Hey there! Can you somehow detect the zerocross and process it on board so that the arduino has to just send the pwm nothing more?
You don't use PWM with AC you use phase modulation. I think the answer is not you need the pulse detector circuit.
Yes obviously. The input is a pwm which is modulated over an ac signal i think. I want to know how the MPDMv4 universal dimmer works. It uses just a pwm input and no zero cross input which is processed internally.
And sorry if I am wrong. I am fairly new to this.
No problem. Please ask if not sure.
So my question is how can I apply pwm on an moc302x relative to a zerocross with is detected internally?
This circuit doesn't work because the LED only turns on when about 10mA flows and this is when 24x1.41 sin(wt) =22 and this is for wt around 40 degrees which is well above zero detects. Did you test this circuit?
I built and it works as I made it.
@@LewisLoflin how about the fact that it needs about 10mA to flow for the opto coupler to turn on. Maybe am doing something wrong-- not sure now.
24VAC has a peak voltage of 1.41 X 24 =~ 36V. - 36 / 2200 = 16mA. Put an oscilloscope on the optocoupler transistor collector and see if you have a pulse then get back to me. The optocoupler is more sensitive than you think. If you have substituted the optocoupler then simply lower the 2.2k to say 1.5k or even 1k. Look at the spec sheet and you will find some can take up to 60mA.
The circuit does work as I illustrated with the oscilloscope.
I agree I will get a pulse but this won't correspond to the zero crossing time. It will be well after.
my blb is not dimming properly. the minimum brightness is about 30-40%. can you help???
Change the time delay. If you are using 220V 50Hz the period is 10mSec. Don't delay past 10mSec.
still not working properly...
Is it a led bulb? They are known not to work well with triacs.
interrupt required?
Yes
Code is at the website.
www.bristolwatch.com/ele2/zero_crossing.htm
Hello.
With zero cross detection AC regulator I would like to control welding transformer, but I saw at the scope that for example at 50% switch the transformer always will get the maximum voltage at turning on.
It would be better to turn on at 0V and turn off at some point not vice versa.
Can you please help how could I do that?
You are not dealing with DC. An AC voltage is often an average known as RMS - DC equivalent. The longer the voltage is turned on the more power delivered to the load.
@@LewisLoflinWhat are you talking about?
I did not mention DC voltage.
@@szabojozsef7873 Do you know what RMS is as it relates to AC?
I am not talking about RMS voltage neither DC voltage or PWM.
Vrms=Vpeak/sqrt(2)
Da geht was
Sir,can i get your email id please.i have some issues related to my project and i want some solutions from you.
lewis@bvu.net