Michel:

Check out the Microelectronic solid state relays available from International
Rectifier, particularly the PVAZ172. These optoisolated AC switching components
come in an 8 pin DIP and beat precision reed relays for thermoelectric contact
noise, speed, isolation, bounce, lifetime, and a few other ways (like power
dissipation).

These things are a very well kept secret, for some reason. I've been using them
for about 10 years or so.

Michel Van den Bergh wrote:

> Hi,
>
> What is the best way for switching components (mostly resistors or
> capacitors) with digital logic. I need this in order to be able to design
> an auto ranging instrument (based on a PIC of course). I know about the
> 4066 (CMOS switches), but the on restance of about a hundred ohms just
> seems too high for most applications.
>
> Regards, Michel