Homey Community Forum

Sensing ON/OFF status for a bargain

Hi there,

I want to sense if a device is ON/OFF. An oven, the washing machine etc.
Since the oven is directly wired and the washing machine does loose its programming when power gets cut, smart sockets are of no use for me.
So I though, why waste 50-60€ for something I will not use to its potential.

I was thinking about homeduino and some kind of current sensor, but struggle to find the right sensor.
I looked at the YHDC SCT-013-000 but found is analog. Since I want to use some esp8266s that I already and these are ESP-01 it has to be a digital solution. Or I have to buy an adc, which adds komplexity and cost.

But I only have to sense the on/off state, so maybe there is a way to “hack” something together that just flips an input? Like, winding a coil around the wire or something?
Or maybe there is a sensor I am not aware of that is digital?

Any Ideas?

Thanks a lot
Juri

Oh wait, will this work?

A power socket can messure the power difference when its on or off. So you can use it to detect it.

The plug it self you can always keep on

I’m fairly certain that clamp-type current sensors are always analogue, and digital solutions typically require that you connect the wire under test to the PCB of the sensor board.

But the ESP8266 does have an ADC pin on board and you can hook up an SCT-013-000 (relatively) easily to it (it’ll need a voltage divider and a cap). See this page for example.

As @RoyWissenburg stated. The powerplug for the washing machine can stay on. @Rocodamelshe made a great flow for this. Ofcourse these powerplugs make your mesh also a bit better.

If its Zwave we are talking about, i would just go with a plug in socket and/or a flush mounted switch (depending on the electrical connection) that has current measurement.
I’ve done it like that, its around 30-45 euros for each, hazzle free direct from the box. (Telldus/fibaro/aeotec and others)

And it will not get as cheap as one might hope, making a own current meas board with sensor (wemos/ESP8266 based etc), not worth the hazzle in my world.

@Marcel_Ubels @RoyWissenburg
Sure I cloud do that, but it won’t be cheap. Also it won’t work for the oven, which ist connected directly to a heavy duty wall terminal (it’s called herdanschlussdose in Germany) which is three phase AC. I’m pretty sure that won’t work with a typical in-wall switch. Not even sure if the aeotec heavy duty switch will work with three phases, nevertheless will it be much to expensive.
@Westerlind.r Oh, tinkering with electronics is what I’m really getting into nowadays, so that’s fun for me. I love DIY.
@robertklep Yes, that’s a good start, thanks. The esp-01 type esp8266 that I have here lack the analog pinout, only two GPIOs. So I could get an esp-12 or something, but have you (or anyone else) worked with hall sensors before? In my understanding they sense magnetic fields and work digital, so something like the KY-003 could work. Ideas? :smiley:

It’s a PITA, but you can break out the ADC of the ESP8266 on ESP-01 boards, but it’s probably easier to use an ESP-12 or (my preference) a Wemos D1 Mini clone (not much more expensive and have built-in USB-to-serial).

I can’t remember ever having used digital hall effect sensors; the ones that I know (especially for power measurement, like the ACS712) output an analogue value (and also require splicing it into the live feed).

ah okey! ye back in the days i though same, before life came in between;)
Just saying it can cost the same or even more depending on how much stuf u already have:)

Like an ESP based (cheap micro controller) as i allready mentioned. If its not the cost/effort value…i would go with an ESP8266 board or similar (wemos/ESP12/ESP01 what ever, same basics) + current shield/board+ non-invasive AC current sensor.
Thats like 20 euros + shipping. If u have all the other stuff (resistors/connectors/box/PSU and more).
Guessing it must be a bunch of examples and codes on all those electronic forums about this…if you wanna be lazy;)

Thats the best way to go, all other are just ppl being complicated and doing complicating stuff for no reason :sweat_smile:

Have fun!