DIY Dumb Alarm clock to ST (door sensor)

So I wanted to take an old AC (digital) clock radio from the 90’s and connect it to ST. Due to there being no really good way to automatically trigger wake up routines with an alarm (for those of us who don’t get up st the same time every day).

Basically, all you do is set the time for the morning wake up, and when it goes off, it opens a door contact which triggers your Smart routine.

I thought of wiring a door contact sensor to the speaker with a dry contact reed switch. it the speaker is Obviously puts out variable output so it may not always close the relay.
At the suggestion below, I used a sound/light activated relay. It cost $7 on eBay. I wired up contacts off the speaker terminals to the microphone input on the relay module. If you don’t want the alarm clock to make noise, but simply trigger the door sensor, just clip the speaker contacts and solder them directly to jumpers to relay board. I chose to solve the jumpers right onto the speaker contacts and keep the speaker.

It took a bit of calibrating the potentiometers on the relay module:
Turn up sensitivity of audio input, turn down light sensor input, and shorten delay on contact (time it takes to shutoff after input stops). I set my delay around 7 sec.

So when the alarm goes off, it triggers the audio input of the relay which opens the door contact, (normally “door sensor = closed”)

So all you have to do is head down to goodwill and pickup any alarm clock. New or old, AC or D.C. Powered. Grab anything you like for $5-8.

Pickup one of these:

Pickup any ST compatible door/window reed sensor.

Power the relay with a USB cable, just chop the end off. Solder jumpers onto speaker positive and negative, and run to relay module input.

Wire NC relay to a door contact sensor, use one with external screw terminal contacts, or solder fine wife to ends of reed switch.

All less than $25 including a cheap door sensor like Xiaomi zigbee sensors.

1 Like

The speaker wire carries alternating current to produce sound. You’d have to build a rectifier and a filter to convert it to DC and then feed it to a relay connected to dry contacts (e.g. door/window sensor).

1 Like

Project finished, see write up in post 1.

1 Like