[amsat-bb] Re: G5500 Elevation Rotator Short Circuit?

Clive Wallis clive at g3cwv.co.uk
Sat Oct 22 05:26:17 PDT 2011

Hi Lynn,

Many thanks for your comments.

Good point, although the contacts are normally closed, and open when the 
motor over-runs. So the usual problem of poor contact wouldn't apply. 
However, it's possible that the contacts may have welded together.

I think that to fully protect the motor it needs a controller
to limit the time that current is supplied to the motor, to a safe 
value. A nice little PIC project!

BTW I've recently had a problem with my central heating where a micro 
switch stuck in the ON position, leaving the boiler firing, when it 
should have been off. However, this was a normally open contact.

73    Clive   G3CWV

Hitchin, North Hertfordshire, UK

On 16/10/2011 13:16, Lynn W. Deffenbaugh (Mr) wrote:
> I'm not familiar with rotors, actually, but micro switches that aren't
> switched often (like only when you run the rotor to the stop, which I'm
> assuming most people try to avoid) kind of limit the effectiveness of
> "self-wiping" or "self-cleaning" contacts. I'm just comparing it
> mentally with my doorbell button that needs a bunch of "vigorous
> activations" (aka pounding on it) periodically to keep function on a
> "push once, ring" basis.
> So, unless you make a habit of running the rotor to the stops, the
> switches may not function when/if they ARE needed.
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

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