We have electric 3 mattress heaters at home. Each is turned on/off by a momentary push button. It takes ~30 min to warm up and we always forget to turn them on in time. Timed electrical outlet doesn’t work, only pushing the button turns a heater on or off.

I came up with the following design to allow both automatic switching at desired times and manual override. In general this system can be used for remote control of various home devices turned on/off by toggle or momentary switches. User interface is implemented as a simplistic web server. It’s certainly a reinvention of the wheel, but I just used this as an excuse to tinker with RaspberryPi, Arduino and wireless communication modules :)

Step 1: Parts for Control Hub

you might be able to connect the bed heater's pushbutton to the arduino instead of the internal circuit this way, it might be rather easy to implement the push button functionality. great project!
<p>Thanks!</p><p>Are you talking about the ability to detect an event when heater push button is manually pressed? </p>
My formulation might've been a bit bad, i wrote that first comment while i was getting out of my train...<br>what i wanted to say is: <br><br>In order to use the original button as it was used without your mod, <br>you could cut the traces that go to the pushbutton on the heater mattress controller, connect the pushbutton to the arduino and route the optocoupler to where the pushbutton was connected before. then you'd need some simple code in order to turn the mattress on when you press the button.<br><br>my english is not really good as im austrian and 15 jears old... i still hope you understood what i tried to say
<p>I actually think it's possible to detect the manual press of a heater push button. We can measure the voltage between output terminals of the optocoupler, which is connected in parallel to the external switch. When this voltage drops to 0 when there is no signal from Raspberry to do that, it means that external button was pressed. <br>Two nuances here: <br> a. polarity becomes important, we need to find which of the two wires is a (-) and connect it to Arduino's ground.<br>b. If heater circuitry operates at much higher voltage than 5v it can fry Arduino when directly connected to its input data pin. <br>Probably this can be resolved with a clamping diode or another optocoupler. I'll try to do something like this, but won't have time in the next few weeks :)</p>

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