[sdiy] Relays or reed switches for routing?

Gordonjcp gordonjcp at gjcp.net
Tue Jun 1 12:26:06 CEST 2021


On Tue, Jun 01, 2021 at 02:08:11AM +0200, cheater cheater wrote:
> On Mon, May 31, 2021 at 9:56 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
> >
> > > The fine layer of oxide on the contact that never gets wiped away and never gets "burnt through" because the current is too low.
> >
> > The highest quality relays can't have a layer of oxide as gold plating on silver nickel simply cannot oxidise - it's chemically impossible.   The thickness of the gold plating determines the lifetime of the relay, with ones available for over a million operations if you want.  But a typical 100,000 operation one will be more than good enough for any audio application I can think of.
> >
> > Or if you want something a little cheaper the hermetically sealed but unplated or rhodium plated silver nickel contact ones likewise won't oxidise as there is no oxygen in the sealed contact area.
> >
> > It's only the vented ones with pure silver contacts that do what you suggest as those have the lowest resistance and are designed for switching power lines or high current signals, not low level audio signals.
> 
> Given the "good" relays are so insanely expensive, would it make sense
> to take vented relays, put them in a form / cast, flush them out with
> something like argon, and pot them?

Or, use analogue switches.  They will track far more accurately that you can measure, and far more accurately than some random bunch of resistors and relays.

-- 
Gordonjcp


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