I have a decade voltage divider used for range switching in my project. I need a way to switch the multiple different voltages that the divider creates into one output, sort of like a multiplexer shown in the diagram. The device also needs to be able to tolerate 500v on the input, but does not need to be able to switch it to the output.

I have tried mosfets in a simulation, but could never get them to work. If I can't find anything else, I could just use relays, but i'd rather not as they are expensive.

Any help would be great, thanks.

• Your not going to find a 500V multiplexer, they aren't on the market. Any other multiplexer would be fried instantly. Your going to have to use mosfets. – laptop2d Jul 26 '18 at 4:08

The device also needs to be able to tolerate 500v on the input, but does not need to be able to switch it to the output.

That's a bit of a puzzle, because you've shown the output able to receive 500V.

If we follow your diagram, and the output does get 500v, then we need something that will tolerate 500V, like a relay or a FET.

If we follow your text, then we have to guess what you're trying to do. Perhaps it's the input ranging on a meter. The standard way to range a high input voltage meter with low voltage switches is the following

simulate this circuit – Schematic created using CircuitLab

Obviously add more switches for more ranges, and pick exact resistor values (rather than my hand-wavy approximate decade ones)

Vacuum relays tend to be high power and expensive but mercury wetted reed relays are not expensive. \$5 2A 1kV

https://m.ebay.ca/itm/GI-Clare-Mercury-Wetted-Relay-type-CUP-P001A505-1-form-A-one-NO-2A-1000V-coil-5V/253552671880?hash=item3b08eabc88%3Ag%3APfcAAOSwY45UOw2G&_sop=15&_sacat=0&_nkw=mercury+wetted+relay&_from=R40&rt=nc

You may be able to use a dual SSR plus a conventional multiplexer. Let the SSR handle the 500V and 50V levels, and the 5 and lower you can use a normal analog mux.

Take care as to the maximum off-state leakage though- 1uA @ 25°C for the given part.

If that's not acceptable you're going to have to use something like a relay most likely.