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Re: switch ratings

Subject: Re: switch ratings
From: Tony Krzyzewski <tonyk@kaon.co.nz>
Date: Sat, 17 May 1997 06:49:05

>  /They almost certainly have gold  contacts on the switches
>  /and probably would only support low current DC  unless
>  /specifically stated that they can support higher currents.
> 
>  Gold is used only on very LOW current switches and it
>  is easily burned away if the switch's current ratings
>  are exceeded even for an instant. You won't find any
>  ordinary switches that use gold contacts.
> 

The ever popular RS catalogue from England has two major ranges of switches 
with gold contacts. From their size and quality they look ideal for aircraft 
use and it was to these I was referring - specifically look for DC rating.


>  /Putting  high current DC through these switches could
>  /possibly result in arc over and  welded contacts.

>  / I have never seen....

I can send you a couple if you want. I learnt a long time ago that the RS 
gold connectored switches don't like high current DC. 15A DC is not the same 
as 15A AC! Luckily it was only on a home build computer (yes, it drew 15A at 
5v and still only had 2k of memory!!). Took me some time to work out why 
those switches kept failing though.
> 
>  /RS do have some miniature toggles with high current
>  /DC contacts - my  catalogue is in the office and I
>  /am a home wid a code so I can't dig out the  numbers.
> 
>  The miniature toggles are generally limited to 5 amps
>  and they have pretty close contact spacing when open.
>  I do not recommend these devices for power control in
>  airplanes. They're fine for audio and instrumentation
>  switching or power control under an amp or so.

The RS ones are rated to 10A DC but ditto.

>  Then it doesn't matter WHAT kind of switches you use. I
>  hightly recommend the standard toggles that mount in 15/32"
>  round holes. They are universally produced by hundreds
>  of manufacturers, they are available with .25" fast-on tabs
>  for easy installation and replacement. My idea of the
>  ideal switch is one that can be replaced in 5 minutes for
>  $5, sitting in the pilot's seat with only a nut-driver in
>  hand.
> 

Its also a hell of a lot easier making round holes that it is making square 
ones I can tell you!!

---------------------------------------------------
Tony Krzyzewski    tonyk@kaon.co.nz
Managing Director  Ph 64 9 358 9124
Kaon Technologies  Fx 64 9 358 9127
Auckland
New Zealand

Networkers visit www.kaon.co.nz
Aviators visit   www.kaon.co.nz/europa/272index.html
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