|Below are photos and the schematic for the HexFet board. It can
be interfaced with the CT-2 controller to provide direct control of DC
motors. The supply voltage for the motors is applied to the board
and the outputs from the board connect to the motors. The board
has 4 channels, UP, DOWN, CW and CCW. There are inputs provided
for push button switches to manually control the motors, and there is
safety lockout circuitry on the board to prevent trying to activate both
directions at once. These Hex FET's can handle current up to 20
In addition to motor control, the board also passes through signals, from the CT-2 controller board, for A/D position readout and motor speed control.
Referring to the two photos below, you can see all the connections you are likely to need. Some comments are in order.
1. To easily connect to the CT-2 board and deliver all the signals needed, the DC power must be applied to this board and fed through to the CT-2. So the DIN plug going to the CT-2 is wired to the eight pads identified below to the left. The pads are numbered 1 through 8. and they should be wired to the corresponding pins on the DIN connector (pad1 to pin1, etc.)
2. The DC motor connections are to the solder lugs connected to the top of each Hex Fet heat sink. They are identified as positive and negative in the photo below, but you will need to test to be sure the motors turn in the direction you expect when actuated. If not the leads from the motor will need to be reversed.
3. In the lower photo it shows where the potentiometers for A/D encoding are to be connected. On each set of 3 pads, the upper pad is ground (-) and the lower pad supplies +5 VDC to the potentiometer. The center pad connects to the wiper.
4. On the left side there are connections for switches that can be installed to manually control the motors. There are two sets of pads labeled Con and Con1. Starting from the bottom of the board, the 4 connections are for Down, CCW, Up, and CW. Each of those pads can be switched to ground to manually control the motor.
We strongly recommend to use a 3 position switch, with center off, and spring loaded to automatically return to center when not held on. When manually controlling the motors there is no built in protection against rotating past the end points. If you forget to turn off the switch and step away you could do damage to your antenna system.
5. If you have speed control capability on your motors, the Hex Fet board provides a buffered output for each direction. The inputs from the CT-2 board connect to the pads labeled AZ1 and EL1. AZ2 and EL2 are the outputs to your motor speed control lines. The 4 pads are easily seen in the upper left hand corner of the board. These outputs simply ground the speed control line, so if your speed control lines require something different you may have to add additional circuitry.
Schematic of the HEX-1 Board. (Full size schematic below).