[sdiy] Two unrelated questions: Switch loads, debouncing

[George Hearn]

On the flip side, don't forget that some switches will have a minimum
voltage!  Mains Rated momentary switches are a good example, used in low
voltage circuits they will work unreliably, they rely on the arc formed when
switching to break through the layer of oxidization and carbonate the
contacts to make a good connection.. I've had to recall a product for this
reason.. just worth a mention!  G 

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Richard Wentk
Sent: 08 January 2009 15:17
To: flightofharmony
Cc: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Two unrelated questions: Switch loads, debouncing


On 8 Jan 2009, at 14:35, flightofharmony wrote:

> Hello all,
>
> Looking for some input on two questions that have been nagging me  
> of late.
>
> 1) Most switches are specified for resistive loads only, as  
> capacitive loads
> can quickly weld or vaporize the contacts. The question: where is the
> general threshold for this?

Generally all you need to do is make sure the reactive surge current  
is less than the switch's rating. You can guesstimate the surge  
current from first principles, and add a current limiting resistor to  
make sure it's never exceeded.

> 2) This popped into my head the other day: Is there any reason to  
> add switch
> debouncing in entirely analog circuits?

Depends on the circuit. If you're switching a signal path, then yes,  
you want to add some debouncing/filtering to avoid crackles and clicks.

Richard
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