I am still going to mess with a 741 at some point, i make make a tiny amp just to make any sounds the controller makes (like door left open alarm) a little bit louder (no need to be deafening! just a bit louder than the pic can do on its own)
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In North America the sirens on ambulances, fire trucks and police cars sweep the frequencies, the sound does not just jump between two frequencies like in Europe. The sweeping sound can be heard well during background noises and echoes.
I know what. A big dog. Train the dog to bark when the light burns out.
There is a big dog living pretty far from me. It hears a siren long before we hear it and it "copies" the sweeping of the frequencies.
Do any European dogs go, "doo, dee, doo, dee" like your sirens?
We had a old velleman thermostat kit, i took the thermistor out and added a LDR, so when light goes out, the relay on the board triggers, this is now wired to mums radio turned up full blast . It will do for a couple of days while i work on the whole thing, and get the new heaters in