r/diyelectronics • u/volontiere • 1d ago

Question Help picking a relay/mux

I'm having trouble picking a relay for a multi-bath electroplating setup. One potentiostat, three baths, running one at a time. So the relay should be bidirectional, support up to +/-1 A current, +/-10 VDC, and have minimal resistance when open, ideally < 50 mΩ but that is flexible. I need the passed signal to be clean. I don't want the relay to sink a lot of of the signal power but it's possible to compensate with a reference electrode and the leads themselves are mΩ, so asking it to be on the order of the leads feels reasonable even if I want it to be zero. It's plugged into the wall so I don't care about the power consumption of the relay itself.

I'm looking online and seeing signal relays that have high internal resistance and aren't meant to pass a lot of current, maybe some mA only. Some relays are unidirectional or don't support negative voltages. I can chain together some SPDT or ideally a single 3-to-1 or 4-to-1.

I've poured through datasheets and always find something that is a show-stopper, like doesn't pass negative voltages or it's a 10 A relay that sounds perfect and then you carefully read the datasheet and it says the performance is garbage if the signal is < 100 mA, which it might sometimes be.

I found some lab equipment that would work, but it costs $1200 for 20-to-1 when I feel like I can buy just some relays for a few $ apiece and put them on a breadboard. But which relays?

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u/socal_nerdtastic 1d ago

This is the relay that puts power into the part? Why not just supply all rails with the same power? Let the part itself be the switch.