eronn.net > astronomy > autoguider > other controllers

Other controllers

The following procedure may be used to find out if the EQ5 controller modification is likely to work with other controllers.
  1. You need a multimeter or a similar instrument capable of measuring DC and AC voltage, current, and resistance.
  2. Measure the voltage from the power supply driving the controller. The supply voltage should be maximum 30 V DC. The AC voltage should be less than 30 % of the DC voltage. Identify the positive and negative terminal in the connector.
  3. Disconnect the power cable and open the controller.
  4. Verify that the navigation buttons are ordinary switches:
  5. Each switches should have one of its terminals connected to the negative supply voltage (usually ground). The resistance from the switch to the negative syupply terminal should be < 5 ohm.
  6. Connect the power and the motor cables to the controller and turn it on.
  7. When a button is not pressed down, the DC voltage across the switch should be > 3.5 V. The negative side should of course be the side connected to the negative supply. The AC voltage (rms) should not exceeds 30 % of the DC voltage. 
  8. When the button is pressed down the DC voltage across the switch should be close to 0 V (or at least < 30 % of the DC voltage measured in the last step).
  9. Put the multimeter in current mode and connect it between the switch terminals. The DC current should be < 150 mA. The AC current should be < 30 % ofthe DC current reading. 
  10. Repeat step 7, 8, 9 with different motor speed settings, including at least the highest and the lowest speed.
If the requirements above are fullfilled, there is a good chance that a modification similar to the one described for the EQ5-controller will work for your controller.

If you find that the navigation buttons consist of switches, but the measured voltages and currents are not within the ranges requested above, a possible solution may be to use relays coupled that in parallel with the switches. The LN2003 circuit can then be used to activate the relays.
Back to the EQ5 modification page 

Erlend Rønnekleiv, www.eronn.net
erlend.web&eronn.net [replace & with @]