Gold Plating

Black Hole

Black Hole

May contain traces of nut
Anybody know anything about it / can do it?

I have some rotary switches with silver contacts (can't get anything else in low quantity) and I want to increase their reliability. I've seen videos about how it can be done, but the chemicals are expensive for a tiny one-off job (and kits extortionate). If I knew somebody who already does it...
 
Rodders53 said:
Why do you think gold-plating a wiping contact will improve reliability?
Click to expand...
Silver tarnishes, gold doesn't. Plenty of connectors are easily available with gold plating, just not the kind of switch I need.

I agree it would be subject to wear with cycling, but this is not going to be cycled much. Far more important to have a non-tarnishing surface, as we always did for PCB edge connectors etc.
 
Solved (not in the way originally envisaged).

My need was for two 2P6T MBB* switches, and I could only find 2P6T BBM* switches with gold plating. However, by cannibalising another pair of BBM switches for their wipers, I modified BBM to MBB. This was only possible because of the exact construction of the (no longer in production) Italian switches I managed to source.

* MBB = make-before-break, AKA "shorting"; BBM = break-before-make, AKA "non-shorting".

These switches are being used to set the gain of an op-amp stage, including the resistance in the negative feedback loop, so if the contact breaks in transition and the negative feedback loop becomes open-circuit, the op-amp stage output becomes uncontrolled and glitches to the voltage rail. MBB is therefore vital (as is a reliable contact)!

Some kind of solid-state gain switching might have been better, but a lot more work and at risk of non-linearity.
 
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