ON/ON Switch -> Impulsion Switch - HOWTO? - Page 1
Forum section: electronics / beginners

author: sebi
author_rank: Newbie
timestamp: January 05, 2021, 03:55:32 pm
content: My goal is to integrate a zigbee switch inside a standard wall switch mount to make it look standard.- My zigbee switch is a one button impulsion switch that can be bind to a light bulb.- The wall switch is a standard 2 position SPDT ON/ON switch (Single Pole, Double Throw).Thus, what I would like to build is a simple electronics circuit that can generate a pulse every time the wall switch moves from one position to the other.I would like this circuit to use energy only during the transitions (not energizing logical gates all the time for instance).I have something simple in mind made out of a capacitor, a resistor and a mosfet (x2). But as a noobs, it is not mature yet, and I am unfamiliar with the notions of quiescent or leakage current.Any hint? Thanks

author: Terry Bites
author_rank: Super Contributor
timestamp: January 08, 2021, 01:38:21 pm
content: I wouldn't do it unless you can properly assess all the risks.You may see cheap (and fatal) circuits shown on the web.Do not use any form of direct coupling from mains to you project. Use magnetic or optical isolation rated for mains use.Here is a low power solution, it to generates a pulse train at twice the line frequency while the AC is on.https://www.radiolocman.com/shem/schematics.html?di=337399The input capacitor must be class Y rated!I have not tested these circuits- Do these things at your own risk.

author: Syntax Error
author_rank: Frequent Contributor
timestamp: January 08, 2021, 02:18:53 pm
content: Have you investigated capacitive touch switches?From my DIY store, a touch panel light switch, with the electronics safe behind a layer of glass, costs around $10

author: Terry Bites
author_rank: Super Contributor
timestamp: January 08, 2021, 05:48:17 pm
content: Not too shabby and no magic smoke.Do not alter R1 or C1 types. Works on 240/110. Fuse is a must. A suitable MOV is always good idea.My understanding is that the worst case pull-up on a Zigbee module is 30k- I used 20k and it was ok, rising edge a bit slow.But then that's Darlington OptoCouplers for you. Are Zigbee inputs Schmitt?I wont show the photo of the lash up in-case you think this is how to build stuff that'll get you killed.AS EVER, DO IT AT YOUR OWN RISK!!!Anyone understand how to put my images into body without linking out to a url? Which I aint doing.. ever.

author: sebi
author_rank: Newbie
timestamp: January 15, 2021, 06:20:34 pm
content: Thanks to all of you for willing to help!I was not clear: I don't want to use mains.I just want to use a standard wall switch (as it is already there), unplug it from mains, and wire it instead to a zigbee switch that I will hide inside.The zigbee switch will then be binded to a light bulb.My issue is that the wall switch provides permanent on/off states whereas the zigbee switch requires impulsions.Thus I would like to place in between the on/off wall switch and the impulsion zigbee switch some electronics powered by the zigbee switch to generate impulsions out from the permanent states of the wall switch, to trigger the zigbee switch properly.I hope I was more clear this time...Sorry for not answering earlier: for any reason, I didn't get any notification emails when you guys answered me on the forum.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 17, 2021, 07:50:38 pm
content: Quote from: Terry Bites on January 08, 2021, 05:48:17 pmAfter publishing, open the attached image so that it is complete, click the right button and copy the URL - you will get the URL of the image on the eevblog site, then edit meggage and paste this link as [ img ]<URL on eevblog>[ /img ]

author: Simon
author_rank: Unknown
timestamp: January 17, 2021, 08:00:33 pm
content: I am a bit confused as to what is required. If you want to toggle and and of when pressing a button you could look at latch relays. I am not sure though if they do mains voltage coils, 5 and 12V for sure.

author: Brumby
author_rank: Unknown
timestamp: January 18, 2021, 01:36:52 am
content: Requirements (as I understand them)1. Input device = standard wall switch (SPST/SPDT?)2. Output = pulse (Characteristics of which are not specified)3. Conditions for output = one pulse for each change of state of input device (Specifically, one pulse for switch moved down and one for switch moved up - that is, two pulses per cycle.)Environment:NONmains.