SkySensor 2000

Power Supplies and Slew Speed

The SkySensor needs a 12 Volt external power-supply capable of sourcing 2 amperes. It comes with a battery holder that needs eight, D cell batteries. I quickly determined that I did not want to keep feeding batteries to this thing. My SkySensor now has two power sources. One is 1.2 amp, 13.8 volt AC adapter that was salvaged from an old Logitech Scanner. The other is a 12Volt, 12 amp hour battery. Another good choice would be the Portable Power Station available from Orion. Using these alternative power sources required attaching an appropriate connector. The connector is a common female, 2.1 mm barrel connector obtainable from Radio Shack. The center post needs to be wired to the Negative power supply lead.

 Be Careful! There are a lot of "Cigar Lighter" cables with a connector that looks just like the SkySensor 2000 connector. The problem is that these cables provide a center positive post. These are not compatible with the center negative SkySensor 2000. You can use them if you reverse the wires.

 To get a feel for the SkySensor 2000's power requirements, a amp meter was hooked up in series while the device was put through its paces. The following is the results:

 No motors running ~ 0.15 Amp

RA motor running at sidereal speed ~ 0.20 Amps

One motor running at full speed ~ 0.90 Amps

Two motor running at full speed ~ 1.40 Amps

Maximum surge current ~ 1.60 Amps

 In order to determine the differences these power supplies would have on the maximum slew speed and to determine the maximum slew speed, the SkySensor was timed in a set slew from 0/0 degrees to 45/45 degrees in altitude and azimuth. When powered by the AC adapter, the elapsed time was 17.28 seconds. When power by the 12-volt battery, the elapsed time was 21.16 seconds.

 Given these results, it appears that the maximum 2D slew speed was 2.6 degrees per second. This corresponds well to the advertised 5.0 degrees per second advertised rate if you assume that rate is based upon a 1D slew.