celestron ultima 8 hand control mod

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rajuncajun5544
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celestron ultima 8 hand control mod

Post by rajuncajun5544 » Tue Oct 27, 2009 6:32 pm

Hi,

I have a celestron ultima 8 controller. I have traced the circuit and think I know how to connect the relays. It looks like the following colored wires get shorted to the black wire when one of the switches to control the mount is pressed.

blue = RA
red = RA-
yellow = dec+
green = dec-

There are also black and white wires. (2 wires - one black, one white for 6 wires total)

This controller also has an LED chart light and focus +/- controls. I know I don't need to worry about that stuff but it's making it hard to decide where to tap in to get the +5V supply for the relay coils. If I measure from one of the colored wires to the white wire I see +5V. But if I measure from the colored wire to black I get 0.012V. It doesn't seem like I should be using one of the colored wires for +5V power to the coils if the same wire gets shorted to black to control the mount. Interestingly if I measure from black to white I see about 0.1V, not the expected -4.9V. I can't figure out how the white/black potential isn't greater.

Anyone added relays to this controller before? I've added a pic to illustrate what I mean.

Thanks!

Andy
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dpanderson
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Re: celestron ultima 8 hand control mod

Post by dpanderson » Tue Oct 27, 2009 8:09 pm

I suspect the white wire is not a true power supply, but some sort of input/output pin into the base of the mount. Or, at the very least, it has a resistor in series with it inside the base. Thus, it could not be used to power relay coils. I think you will need to tap into the mount itself.
Doug Anderson
Shoestring Astronomy
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rajuncajun5544
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Re: celestron ultima 8 hand control mod

Post by rajuncajun5544 » Tue Oct 27, 2009 9:17 pm

How about using 2 or 3 AA batteries that are in the enclosure with the relays?

I'll have extra room in the PJ box anyways.

dpanderson
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Re: celestron ultima 8 hand control mod

Post by dpanderson » Wed Oct 28, 2009 7:11 am

That would work fine. Relay coils can be power hogs, so I'm not sure how long a set of batteries would last.
Doug Anderson
Shoestring Astronomy
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rajuncajun5544
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Re: celestron ultima 8 hand control mod

Post by rajuncajun5544 » Wed Oct 28, 2009 7:25 am

Ya, I power the mount with a 12V deep cycle so I could tap into that. Might be better for longevity.

Thanks for all the help!

Andy

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