Yann Guidon / YGDESI noticed only now some details I didn't see before: these 3V relays are rated for 150V 100mA max. (under which conditions ?)
Given that it takes 60mA to energise one coil, the amplification coefficient is barely 2 and the design expects more.
It was a good idea to connect coils in series wherever possible. Control signals still require a large fanout and I'll probably have to implement a 2-levels signal tree (with repeaters for each nibble or two).
Given the current handling, it would have been wiser to opt for a higher coil voltage, which reduces the required current, thus a better amplification factor.
That, and DPDT, will be considerations for a next version, if any !
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I guess that a 24 or 48 volt AC relay would be better choice for getting a large fan-out. But the AC relays might be slower due to the shading coil so in a high speed situation DC relays would be better and then accept the lower switching ratings.
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For now, speed is not an issue : I just completed a ring oscillator at about 1.6Hz. I'm not sure I can make a difference between AC and DC relays, i've never heard about a "shading coil".
The relays I use are DC-compatible anyway :-) They can switch pretty fast but it's only the beginning of the story...
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The shading coil is basically just an short circuited internal extra coil on the core that holds the flux alive a bit longer so the relays doesn't hum (or even chatter is fast enough) when run on AC.
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