Noiseless Contactors and Relays

Solid state relays are the way to go as suggested by Mr. Doorman..

Solid-state switches have some of the lowest noise, but they are not noiseless. Reducing analog noise in a circuit is a complex task that most underestimate. I expect the rest of the OP's circuit contributes more noise than any of the switches associated with the circuit.

The OP does not specify whether he is referring to audible noise or electronic noise. I presume you are referring to electronic noise.

If Solid State Relays create audible noise, it's well below my poor threshold of hearing.

Also, when he says "...noiseless brand...", I presume that he means "...noiseless type...". I'm not aware of a Noiseless brand.

Yes! I was considering the electronic noise of any relay. With no moving mechanical parts to make the "click," a solid-state relay will not be heard outside the circuit it controls.

It also matters if one is switching an AC or DC signal. Some soli-state relays will lock ON with a DC signal.

But what controls the relay coil that switches it?

Fuji, ABB, Phoenix Contact, Crydom, Siemens, and Omron have them.

If you want truly silent operation, I’d look at solid-state relays/contactors rather than mechanical ones. Brands like Carlo Gavazzi, Crydom, and Schneider Electric have solid-state options worth checking out.