• Simplest Relay low-freq oscillator

    01/07/2021 at 23:28 0 comments

    We often want to interface a new alarm system with an old siren and the most common request is to get a flashing light ...
    You will say what's the problem ... just a NE555 in astable configuration! Or others will say there are finished modules where you just need to adjust the timer!

    My gripe was to create something sooooo much more ignorant and OLD style (forgive me the older ones here, maybe it will make them smile ...)
    recovering material from an old disused UPS:

    in all I used 2 relays, 1 capacitor, 1 resistor and an optocoupler ...
    Don't believe it?

    obviously the frequency depends entirely on the value of the capacitor, and the duty cycle on the resistance.
    with these values and the 12V relays I had I got about a 1HZ oscillator ... I didn't measure it with the stopwatch but I didn't have big claims!
    The important thing was that it was as minimal as possible, personally I had also made a card with NE555 but after a few months, being out on the outside it went crazy, I had to change the integrated circuit because it no longer wobbled to stay out in the cold. hope this goes better for EXTREME conditions!