Does a relay add noise or interference to its inputs?

[little_carlos]

Hi, i was wondering about that yesterday and i hope you can answer this
since the relay inputs are activated with an electromagnetic field, does that magnetic field causes any noise or interference to any signal that goes through ?

[technix]

There can be some spikes if you are using stable DC to drive the solenoid but like a transformer with a thousand-turn primary and a one-turn secondary the noise is minimal.

However the real concern here is contact bounce which can be significant if you bought one with unsatisfying quality.

[retrolefty]

If you are asking if there is any coupling of 'noise' from coil/magnetic field to the output contacts, then no, there is no realistic concern there.

[tggzzz]

Hi, i was wondering about that yesterday and i hope you can answer this
since the relay inputs are activated with an electromagnetic field, does that magnetic field causes any noise or interference to any signal that goes through ?

Yes, repeat no.

In other words it depends on the type of relay, the operational environment, and the signal.

[albert22]

In this very sensitive application, some precautions in the relay were taken to prevent noise :
http://electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow
- shielding between coil and contacts
- reduced voltage range on the coil.