Electronics and Motor Information

This system was installed around 1983 on both our 18-inch and 41-inch telescopes at the SFA Observatory. Both telescopes have two motors that are controlled with the multi-axis control system described below. See below for an image key and lots of additional information.

Click on the image to enlarge.

Image Key

Large red cables run to the two motors.
12-Volts input is provided by C.
High voltage (~70V) input is provided by F.

This unit supplies 5-Volts to E and both D's.
It also supplies 12-Volts to E.

This unit supplies 12-Volts to both A's.
It is labeled as "logic supply" in the manual.

These two card send their outputs to the A cards via light-blue ribbon cables.
5-Volts input is supplied by B.
These two cards communicate with E via the slots in the back.
An input signal also comes in from a computer's CTM-5 counter timer card. The CTM-5 card sends square waves with different frequencies to the D cards. Basically, this allows us to pulse the motors at an external rate.

This card receives instructions from COM1 of a computer running a Visual Basic or C program.
The card communicates with D via the slots in the back.
This card gets 5-Volts from B.
It also gets two 12-Volt lines from B (V1 and V2).

These supply high voltage (~70V) to both A's above.

Three Cards

Here is another image of the three types of cards in the system above that we would like to replace. Cards A, D, and E are the same as the cards shown in the image above.

Stepper Motors

The stepper motor control system described above is the same for both the 18-inch and 41-inch telescopes. However, the two motors on the 18-inch telescope are different from those on the 41-inch telescope as described below.

41" Stepper Motor Info (Two Stepper Motors)
Superior Electric SLO-SYN
Synchronous Stepping Motors
Type M172-FD-306
HOLD 2700
200 Steps Per Rev
2.35V 15A DC
SPEC BM101025
Continuous Duty
65 degrees C Rise
Class B INSUS

18" Stepper Motor Info (Two Stepper Motors)
Superior Electric SLO-SYN
Synchronous Stepping Motors
Type M112-FJ-327
HOLD 1125
200 Steps Per Rev
2.1V 4.2A DC
SPEC BM101025
Continuous Duty
65 degrees C Rise
Class B INSUS

Motor Links

Dan Bruton
Department of Physics and Astronomy
Stephen F. Austin State University