First project | Automating an old washing machine

[Jordy207]

Hi everyone,

I was attempting to automate my old washing machine so I could trigger it to start after x hours through an ESP32. This is my first electronics project.

I figured out all the control for the ESP32 just fine, but then it came to wiring the trigger to the PCB of the machine. This turned out to be a spring capacitive touch sensor (I don't know the official term), and I found someone else with the exact machine and idea; however, they were using a Shelly 1 and not an ESP32.

I started with wrapping a wiring around some coils of the spring but it wouldn't trigger with just signal from the esp32(I tested the workings of my code outside of the machine and it did what it was supposed to), but it would still trigger using my finger either on the button or somewhere on the wire from the ESP32.
It was then suggested to add a 10-47nF capacitor in between, so I got a 10nF capacitor and still no luck. The last tip was to use aluminium foil around the spring for better contact and connect the GPIO wire of the ESP32 to that foil.
Once I tried this, I wanted to verify the button still worked without the ESP32 even connected to the wire, and that's when my PCB shorted the moment I removed my finger from the button..

My question is, I don't see what I did wrong, and was wondering if any more experienced people could tell if what I did is even a good way of going about it, and if so, what could've caused the short?

I've attached a picture of how I attached the wire without the foil(this didn't trigger the button) and with the foil and wire to the spring. And for fun, a picture of the ruined PCB haha

Thanks in advance,
Jordy

[ledtester]

... and I found someone else with the exact machine and idea; however, they were using a Shelly 1 and not an ESP32. ...

A Shelly 1 is a Wifi relay switch. I would implement what they did using a relay controlled by the ESP32. The difference is you avoid any potential interaction between the power supplies of the washing machine and the ESP32.

Update: Are these the pages describing the Shelly approach?

https://community.home-assistant.io/t/siemens-washing-machine-pushing-start-button-with-shelly-shelly-1/573595/2

https://www.mikrocontroller.net/topic/554673

[Jordy207]

Those are indeed the pages I meant, I should have linked them in my original post, my bad!
How is it different using a relay to send power over a wire compared to using the GPIO of the ESP32 and switching the output value to 0 to simulate the touch? Are you not practically doing the same, but with a relay?

[m k]

Galvanic isolation.

[RJSV]

   Jordy:
   My sister's project was / is to establish a practical wash machine for a large household,  in a settlement w no electric service, or water or sewer.   We helped her obtain the washer, in a waste dump STORE that recycles large discarded appliances.
   She also bought a water pump, as we have no water head pressure.
One unexpected turn of events, is that she now states that an 'older' machine would be a lot easier to work with, doing manual adjustments as the wash cycle progresses.   Automatic, smart machine often just sits there, flashing a stupid 'code', like LL 43.

   I hadn't anticipated that would be the case, with newer machines.  Now, she states that an old wash machine would let her do the customized wash cycle that she wants,  sitting there as the machine does it's thing.  (I taught her to not run the water pump,  unless it has water going through it,  due to OVERHEAT...naturally).

   I'm always observing discarded old wash machines, along the roadside,  and have thoughts of conversions, to a rock sorting machine, DIY.   Sister wants to use an older clothes dryer, as a center for a backyard Fire Pit !
   Artists,  these days...huh ?  But the projects are enjoyable, and help the recycle efforts.

[tooki]

Hi everyone,

I was attempting to automate my old washing machine so I could trigger it to start after x hours through an ESP32. This is my first electronics project.

I figured out all the control for the ESP32 just fine, but then it came to wiring the trigger to the PCB of the machine. This turned out to be a spring capacitive touch sensor (I don't know the official term), and I found someone else with the exact machine and idea; however, they were using a Shelly 1 and not an ESP32.

I started with wrapping a wiring around some coils of the spring but it wouldn't trigger with just signal from the esp32(I tested the workings of my code outside of the machine and it did what it was supposed to), but it would still trigger using my finger either on the button or somewhere on the wire from the ESP32.
It was then suggested to add a 10-47nF capacitor in between, so I got a 10nF capacitor and still no luck. The last tip was to use aluminium foil around the spring for better contact and connect the GPIO wire of the ESP32 to that foil.
Once I tried this, I wanted to verify the button still worked without the ESP32 even connected to the wire, and that's when my PCB shorted the moment I removed my finger from the button..

My question is, I don't see what I did wrong, and was wondering if any more experienced people could tell if what I did is even a good way of going about it, and if so, what could've caused the short?

I've attached a picture of how I attached the wire without the foil(this didn't trigger the button) and with the foil and wire to the spring. And for fun, a picture of the ruined PCB haha

Thanks in advance,
Jordy

You made the same mistake as the person in the mikrokontroller.net thread: you electrically connected the MCU wire directly to the spring, when you were meant to wrap the insulated wire around the capacitive touch spring.

[Jordy207]

Hi, thanks for the reply! After looking a bit further indeed I also noticed this very silly mistake!

I have since received a new pcb and am gonna go the route of a relay triggered by my esp32 with the wire spooled within the spring with NO contact...
Silly mistake like i mentioned but we learn