ESP8266 Community Forum

Our tumble dryer is in our cellar. The only way we can tell whether it has finished its cycle is going is to go downstairs.

I would like to make a little ESP8266 based sensor that publishes an MQTT message when the dryer starts and finishes its cycle. If this works, I'll do the same for the washing machine.

I have a variety of sensors (I bought the 37 sensors kit but I have other sensors and could buy something else if necessary) but I'm not sure what the best type of sensor would be. The obvious options are one of the sound sensors or some sort of movement or vibration sensor.

Does anyone have any suggestions for the most appropriate type of sensor to use for this sort of application?

I think you've hit both the ones I would use, but the movement sensor is probably the simplest. Just look at it every minute and see if it's got a zero or small value.

Sound will always pick up something, often the self noise of the unit itself. Movement can be made less sensitive

An accelerometer module seems to be a popular choice for sensitively detecting the vibration from active tumble dryers or washing machines.

Check out https://www.instructables.com/id/Clothe ... 66-Accele/

That uses a fairly expensive accelerometer module. I suspect one of the much cheaper ones would work OK in this type of application.

I did it by measuring the current consumed. When it's (almost) zero, it's done.

I didn't want to tamper with high voltage, so I bought a very simple power usage meter, containing a red led that flashes for each Wh consumed and glued an LDR on top of it. The LDR (or phototransistor, both can be used) I connected to a comparison circuit and when it flips, it triggers an ESP8266 I/O pin with pin change interrupt. Although essentially not required for a contact-less circuit, you could also add a debouncing circuit.