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🧺 Washing-machine-done alert, without touching mains
“How do I get a phone alert when my washing machine finishes, without touching mains power?”
Two safe ways, and neither opens the machine: feel the vibration with a sensor stuck on top, or measure the power with a ready-made, certified smart plug. Both tell you when the wash stops.
What to buy
| Part | Why this one | Rough cost |
|---|---|---|
| ESP32 board | WiFi to send the alert. | $4–8 |
| Accelerometer board (e.g. LIS3DH or MPU-6050) | Measures shaking in three directions. Far more reliable than the cheap on/off “vibration switch” boards. | $2–6 |
| USB power supply and a long cable | Plugged into a normal socket; only low voltage reaches the sensor. | you likely have one |
| Strong double-sided tape or a small box | Fixes it firmly to the top of the machine. | $2 |
Prices are rough ranges, not quotes. Check the current price and stock before you order.
What to install
A short Arduino sketch, or ESPHome: read the accelerometer a few times a second, decide “running” or “still”, and alert when it has been still for a few minutes after running for a while. Send it with ntfy or Home Assistant.
Build it in three steps
- Watch the numbers. Stick the sensor on the machine and log the readings through one full wash. You'll see filling, washing, pauses and the spin.
- Set two rules. “Running” means shaking above a threshold for more than a minute. “Done” means no shaking for 3–5 minutes after running.
- Alert once. Then reset, ready for the next wash.
What catches people out
- Pauses look like “done”. Machines stop to soak or drain. That's why “done” needs minutes of stillness, not seconds.
- Other vibrations. A dryer on top, or footsteps on a wooden floor, can trigger it. Set the threshold from your own logs.
- No current clamps inside the plug. Clamp sensors need one wire separated out of the mains cable, and that is mains work. Use the certified smart plug instead.
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