AVR-Chat

It looks like this application is handled, Steven.  You might also want 
to keep the following in mind for future apps:

Silver alloys are fine for "power" applications but they're severely 
limited when you get down in the mud with really low currents because 
the contacts will build up an oxide or a sulfide coating.  This is why 
they depend on the small amount of arcing that will occur in a power 
circuit.  At low currents, such as driving a logic input, you'll need 
gold inlay or a gold flask over silver contacts.  The same holds true 
for relays.  Be sure to9 look at the minimum current ratings for 
switching devices.  There's also a difference between switching current 
and carrying current capacities.

Voice of experience...don't ever try to drive a logic input with the 
auxiliary contacts of a motor starter.


REB



Steven Hodge wrote:
> Thanks for all your input.  Got it.   I'll use the 28 VDC rating for 12 v.
> I need to make/break 3.5A so I'll have to switch (pun intended) to a switch
> rated at 4 A at 28 VDC instead of the 3 A one I was hoping to use (for
> aesthetic compatibility with adjacent switches).  Steve
>
>  
>
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
> Of David VanHorn
> Sent: Tuesday, March 18, 2008 11:24 AM
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] Re: switch ratings
>
>  
>
> On Tue, Mar 18, 2008 at 2:07 PM, Zack Widup <w9sz@prairienet.org
> <mailto:w9sz%40prairienet.org> > wrote:
>   
>> I believe Sander is right. I'd keep the same current rating for lower
>> DC voltages as for 28 volts.
>>     
>
> Right, current is just current, the voltage across a closed switch is
> essentially zero.
>
>  
>   


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