This thread is a perfect example of the XY PROBLEM:

The XY problem is a communication issue that occurs when someone asks for help with a solution (X) instead of the actual problem (Y). The XY problem can cause wasted time, miscommunication, and ineffective solutions.

And I would add, a very poorly described solution.

 

No.

Since you don’t like what I propose, I am done. Have fun.

I didn't say I don't like it.
Just can't find such a prebuild module?

No idea why you are saying that current breaker is way to no.

 

@BobTPH
https://www.ifm.com/at/en/product/C...0FWiW4z660kTjGyWnqcjDGukSN1PEufwaAkL7EALw_wcB

 

@schmitt trigger yes, agree.

 

No idea why you are saying that current breaker is way to no.

Because the current changes from 0 to 100% 100s of times per second. Sensing the current does not do what you want.

The monostable gets around this by extending the pulses so that they are continuous when the PWM is operating. This is what you need to drive a relay.

Likewise, converting the PWM to an analog voltage does not do what you want. It could almost work, but would fail for very low duty cycles. You cannot set the threshold to zero because there is always noise and inaccuracy in the system. And even if that was not the case, a comparator can only have a threshold of zero when it has a bipolar supply.

The solution I proposed will work in all cases with only the 12V supply you are already using. You will not find a a prebuilt module that does exactly what you want.

 

Read this. This is the type of circuit I am proposing.

Missing pulse detector

 

Because the current changes from 0 to 100% 100s of times per second. Sensing the current does not do what you want.

but how can current chance or be higher than 0 in case stripe is off?
did you mean even the the strip is OFF: both current and voltage changes oscillating between 0 to 100%?

The solution I proposed will work in all cases with only the 12V supply you are already using. You will not find a a prebuilt module that does exactly what you want.

okay makes sense, but someone has to design it, correct?


thanks!

 

Read this. This is the type of circuit I am proposing.

Missing pulse detector

i went thru that but its about "missing pulses" ... do i need to detect missing pulses? I think i need to somehow
"scan the state of the led strip" ie is on -> Send signal +12v, is off do not send signal (+12v)

 

current and voltage changes oscillating between 0 to 100%?

Yes! That is what I have said twice now. That is what PWM means.

And the problem is not that that is current when it is off, bit that the is no current part of the tine when it is on.

A missing pulse detector works by changing state when it does not see a pulse within a specific time period. When the PWM stops it will change state after a little more than one period later. That means, probably a few milliseconds at most.

 

It's like you have junior computer engineer and you force him to understand complex algorithm where knowledge of multiple prerequisites is required....

For me it's enough if someone says use that module connect it as that and thats it... Instead of addressing I have to understand ohm law... Pwm... Etc etc..

You've been told what circuit to use, and now you are debating it's correctness.

The 'missing pulse detector' is the conceptual solution to detecting the light 'on', turning the varying PWM signal into a binary on-off.

You are forcing yourself to try to understand it! It's a shame there doesn't seem to be a prebuilt module for that purpose, but keep looking.

 

There is another conceptually simpler circuit that would probably work well. If you charge a capacitor though a diode, with resistor to discharge it over a period or two, it will perform pretty much the same function. But will need a transistor to drive the relay and will not switch sharply like my original idea. It will end up with about the same number of parts and is not quite as good. That is called a peak detector. It is complicated in this case because of the ground line being switched, making it “upside down” from a circuit you are likely to find.

You need to get over the fact that there is no trivial solution and not likely a module that does exactly what you need.

 

Ok, after wasting too much time on the web, I have only found two modular solutions: the RC community has lots of PWM detector modules but designed for RC servo pwm, and it seems the perfect module functionally but for industrial applications.

I think you are going to have to roll your own. Personally I'd reach for a 555 as a missing-pulse detector, with an inverted output turning it into a pulse-present detector. Easy as, bro.

 

You've been told what circuit to use, and now you are debating it's correctness.

yeah... sometimes curiosity... and if its not to complex to get proper understanding why not to get it.

 

You need to get over the fact that there is no trivial solution and not likely a module that does exactly what you need.

understand, i think now i do understand that missing pulse detector and its usage for my case...

I am its fine ... but isn't that https://circuitdigest.com/electronic-circuits/missing-pulse-detector-circuit-diagram
providing the Solution for that? I mean if its schematically (circuit design ) is correct, its not problem to get it "created" and to install it?

 

I think you are going to have to roll your own. Personally I'd reach for a 555 as a missing-pulse detector, with an inverted output turning it into a pulse-present detector. Easy as, bro.

by roll out you mean also design circuit? Who is 555?
and whats the reason behind if u stated that this module is fine https://rct-global.com/part/pwm-sense-switch-controller/ ?
thanks

 

Who is 555?

Are you just playing games here? Way back in post #30 Bob suggested an LM555 as a missing pulse detector can be configured as a PWM detector. There are numerous examples of this on the web, such as the one YOU discuss in your post #54 - that is all about a missing pulse detector using a 555. Did you even read it?

The module I linked to is an PWM detector, an industrial version of what you need. The ONLY modular solution I could find, and no doubt extremely expensive and possibly not exactly appropriate to your requirements, but I haven't bothered to look into it.

 

Are you just playing games here? Way back in post #30 Bob suggested an LM555 as a missing pulse detector can be configured as a PWM detector. There are numerous examples of this on the web, such as the one YOU discuss in your post #54 - that is all about a missing pulse detector using a 555. Did you even read it?

yes i got it afterwards... that you are referring to LM555. but i also believe in case i contact them they dont care

 

E555 application for a missing pulse detector: ti.com/lit/ds/symlink/ne555.pdf (9.2, Figure 16)

the last post 74HCT123 https://electronics.stackexchange.com/questions/296670/detecting-pwm-signal-is-present-on-the-line

or
https://electronics.stackexchange.c...m-signal-in-the-smallest-possible-board-space

 

I was told
that it might work with that module? https://dratek.cz/arduino/51530-modul-rele-dc-12v-1-kanal-s-urovnovym-spinacem.html (this module has to be switch to LOW)

Any idea here?

 

I was told
that it might work with that module? https://dratek.cz/arduino/51530-modul-rele-dc-12v-1-kanal-s-urovnovym-spinacem.html (this module has to be switch to LOW)

Any idea here?

Having a bit of difficulty evaluating that one. Not only do I not speak Czech, but Google doesn’t either.