• The forum software that supports hummy.tv has been upgraded to XenForo 2.3!

    Please bear with us as we continue to tweak things, and feel free to post any questions, issues or suggestions in the upgrade thread.

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.
 
You must log in or register to reply here.
Back
Top