Hi Danko,
I've got a Hantek 5202B. (200MHz BW 1GSA/s) Had planned to to some 100-200MHz design work but it never materialized. I like the scope except it's only 2 channels.
When I was working, my lab scope was a Keysight MSO7104B Mixed Signal Oscilloscope; big difference from the Hantek. Well, it is what it is, right? So, as I said earlier, I will build up the PWM circuit and post results. BTW, suggestions on connecting the line powered circuit to the scope? In the past, I've used an isolation transformer to do this. I know that this can be a dangerous connection arraignment. Any thoughts? I don't have a differential probe.
Thanks,
Neko

Helo, nkojita... I'm *not* Danko...

The reason I ask is because I too own a Hantek scope, but mine is PC-based. It just so happens that every time Win 10 does an update, I have to reinstall its software using a special permission. Otherwise the scope won't work. But yours is of the stand alone type, so my predicament doesn't apply.

I hope you can get your scope fixed soon, or get a hold of another one. Otherwise working in this type of projects is going to be more difficult.

 

Helo, nkojita... I'm *not* Danko...

The reason I ask is because I too own a Hantek scope, but mine is PC-based. It just so happens that every time Win 10 does an update, I have to reinstall its software using a special permission. Otherwise the scope won't work. But yours is of the stand alone type, so my predicament doesn't apply.

I hope you can get your scope fixed soon, or get a hold of another one. Otherwise working in this type of projects is going to be more difficult.

Hi Report,
Thanks for your response and previous responses that I may not have acknowledged. Sorry, my apologies. For me, Hantek sent me to a download link for a firmware update. Bottom line, if the scope won't even boot, it can't download and load a firmware update.

There was no real help from Hantek that helped me resolve the boot problem. I did find however, that the scope would but after sequencing the On/Off switch up to 100 times.

This probably doesn't help you but it got the scope booted to make a few measurements. Still couldn't apply undates. Also had a Win 10 issue with a Signal Hound Spectrum Analyzer PC based.

Neko
.

 

The reason I ask is because I too own a Hantek scope, but mine is PC-based. It just so happens that every time Win 10 does an update, I have to reinstall its software using a special permission. Otherwise the scope won't work.

Also had a Win 10 issue with a Signal Hound Spectrum Analyzer PC based.

It was for me too in Win10 with Hantek DSO-2250 and Owon VDS3102L oscilloscopes,
but last 3 years they work just fine under Win10 Enterprise LTSC.

 

Went down this path some years ago to control a small lathe speed without stopping to change belts.
I would suggest you look at a .pdf from Freescale DRM039 SPIM Control.pdf if you have not already found it.
It has 2 alternate methods with circuits

 

Hi Danko,

I received my new scope today- already have the PWM module that you recommended.

There was a question that I had regarding AC neutral and the LTSPICE ground.

In the the first image, is your latest (I think) complete schematic. Of course for LTSPICE, the voltage source has a return generally called signal ground.



However, in constructing a proto board, there would be no connection between AC neutral and signal ground, right?

I modified your schematic as shown in the second image to include AC neutral. Does this look correct? Also, is there a way in LTSPICE to show an AC neutral connection that is independent of signal ground?



Thanks,

Neko

 

Also, is there a way in LTSPICE to show an AC neutral connection that is independent of signal ground?

N and Gnd must be kept separate in the real world. In Spiceland you can link N to Gnd via a very high value resistor (say 100Meg) to keep Spice happy.

 

Hi Neko,

Also, is there a way in LTSPICE to show an AC neutral connection that is independent of signal ground?

@crutschow already answered your similar question:

You can simulate isolated grounds in LTspice by connecting one ground with the ground symbol, and them connecting a large resistance (say 10meg) from that to the other ground.
That should satisfy LTspice but keep any currents between the grounds to a negligible value.

In LTspice it may looks like as:

But, in this circuit, -5V ("Gnd") need to be directly connected to "Neutral",
because R1, D3, D4, U4, U5, should provide pulses for M3, M4,
synchronized with polarity changes in "Line", without any delays.

 

Hi Neko,

@crutschow already answered your similar question:

In LTspice it may looks like as:
View attachment 216619
But, in this circuit, -5V ("Gnd") need to be directly connected to "Neutral",
because R1, D3, D4, U4, U5, should provide pulses for M3, M4,
synchronized with polarity changes in "Line", without any delays.

 

Thanks for your comments. Is this what you had in mind?

 

So here's a line driven circuit that will produce a sync signal with minimal delay directly from the AC line:


The full article is at this link:

https://www.edn.com/isolated-circuit-monitors-ac-line/

Bottom line is I really don't want to connect the 5V gnd to AC neutral - doesn't seem safe to me.

Neko

 

90 posts and a lot of thought into this, quieting a fan. Must be some loud fan. How about a short video of the fan running so we can see how loud it actually is?

 

Hi Neko,

I really don't want to connect the 5V gnd to AC neutral - doesn't seem safe to me.

It is safe for me, because I will deal with knob of potentiometer U1 only.
Of course you can do any changes in circuit, if you think they are needed.

So here's a line driven circuit that will produce a sync signal with minimal delay directly from the AC line:

Sounds good, but...

 

Hi Neko,

It is safe for me, because I will deal with knob of potentiometer U1 only.
Of course you can do any changes in circuit, if you think they are needed.

Sounds good, but...
View attachment 216738View attachment 216739

Hi Danko,

Thanks for the post. Definitely too much latency to work properly. I found an On Semi app note where they made speed improvements to some basic circuits. The circuit below looked the best in terms of delay (double digit uS):


The app note can be found at: https://www.onsemi.com/pub/Collateral/AND9282-D.PDF

Neko

 

BTW, I should have mentioned that the Bill of Materials is in the appendix of the app note.

 

Attached is a sim of the circuit that just posted. I tried all the optocouplers in the library but didn't see a huge improvement relative to the zero cross time. It's pretty close to 400us, don't know if that's a problem. Screen cap below shows this:



Any comments?

Neko

 

Attached is a sim of the circuit that just posted. I tried all the optocouplers in the library but didn't see a huge improvement relative to the zero cross time. It's pretty close to 400us, don't know if that's a problem. Screen cap below shows this:

View attachment 216784

Any comments?

Neko

By changing the value of C2 to 1n, I shaved off 100us in the delay time:

 

By changing the value of C2 to 1n, I shaved off 100us in the delay time:

View attachment 216785

Hi,

I still like the idea of transformer isolation. Looking on Amazon, I found some very small audio transformers: 1:1, 500V isolation, 20- 20,000 Hz response.

The inductance was specified at 290mH. If they can't handle the full line voltage, I'll knock it down with a voltage divider.

They actual delay can't really be zero as the cursors imply, but it's low. Attached is the circuit and the link to to transformers.

https://www.amazon.com/gp/product/B07HTBQ7FY/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I bought the last lot at this site but there's plenty more similar items.



Thoughts, comments.

Neko

 

I suggest you take a look at the 6N137 opto-coupler. It's got much better speed characteristics than the 4N25 you've been considering.

And for complete and perfect isolation, I've successfully used the CME0512S3C DC-DC converter for many projects in the past. I suggest you give it some serious consideration.

 

Hi Neko,

I guess this solution will make you happy: (You can tune zero crossing by value of capacitor C1)

 

I suggest you take a look at the 6N137 opto-coupler. It's got much better speed characteristics than the 4N25 you've been considering.

And for complete and perfect isolation, I've successfully used the CME0512S3C DC-DC converter for many projects in the past. I suggest you give it some serious consideration.

Hi cmartinez,

Those isolated modules on Digikey are great! Thanks! For the POC prototype, I want to go modular wherever I can. Wanted to try the 6n137 option but couldn't get a LTSPICE model to work. Tried https://groups.io/g/LTspice/filessearch?q=6n137 Do you have a .asy and and/or .sub or .lib file that work?

Thanks!

Neko