FCUSB and Moonlite

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KKKeithBC
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FCUSB and Moonlite

Post by KKKeithBC » Thu Aug 07, 2014 4:01 pm

My FCUSB is unable to operate my Moonlite DC focuser. It works fine on my RIgel focuser. I had expected it to be the other way around, since the Moonlite is said to work with FCUSB, but there is no mention of the RIgel.

The problem appears to be the pinout of the cable. The Moonlite uses a 3-conductor cable, with the "forward" signal (positive voltage) on the tip, the "reverse" signal (also positive voltage) on the ring, and common on the sleeve. The FCUSB and the Rigel use a 2-conductor cable with forward (positive) and reverse (negative) on the tip and common on the sleeve. The ring conductor is not used.

Is there an existing cable that will adapt the FCUSB to the Moonlite focuser? If I have to make one from scratch, it is going to be messy, using diodes to switch the opposite polarity signals.

(BTW, sorry about the stutter in my username. Must have been a keyboard glitch. I am not now and never have been a member of the KKK. :shock: )

dpanderson
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Re: FCUSB and Moonlite

Post by dpanderson » Thu Aug 07, 2014 5:40 pm

Keith,

This is the first time I have heard of this problem. I know we have had customers in the past successfully use the FCUSB with the Moonlite DC motor. It sounds like something in Moonlite's design has changed. I am not sure why they need three pins to drive a DC motor. Normally you just use two terminals, reverse the polarity of the voltage and the motor turns the opposite direction. The only thing I can think of is that they are using separate motors to drive forward and backward.

I will try contacting Moonlite to see if I can get more details.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

dpanderson
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Re: FCUSB and Moonlite

Post by dpanderson » Mon Aug 11, 2014 12:12 pm

I received a reply from Moonlite. About two years ago, when they introduced their dual port controller, they switched from tip and sleeve to tip and ring. So, you should be able to make a cable that connects tip to tip, and sleeve to ring, that will work. If you aren't able to do this, let me know and I should be able to make up the cable.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

KKKeithBC
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Re: FCUSB and Moonlite

Post by KKKeithBC » Sat Aug 16, 2014 12:19 pm

That's great. I'll make up the cable. Thanks!

Keith

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