DIN 8 Jack

**The DIN8 connector and connections**
This page shows the connections for the DIN8 Jack on the CT-2 board. The DIN8 jack has input connections for the power and A/D encoders, and output connections for antenna position relays. All of those functions are documented below.

DIN 8 - Power, Relay, and A/D Connector

1	A/D Input for Elevation
2	CW relay out
3	UP relay out
4	CCW relay out
5	DOWN relay out
6	A/D Input for Azimuth
7	+12 VDC Input to power board
8	Ground

Note that the pins are NOT numbered sequentially

Note: The Up, Down, CW, and CCW outputs are open collector, transistor driven outputs. They can sink a maximum of 800 milliamps, 100 volts. This is designed to drive relays or an H-Bridge to control the motors. See below for information on using an H-Bridge

**Wiring up the A/D Decoders**
The A/D decoders are contained within the PIC18F4850 processor chip and can accept a maximum input of +5 volts. So you must wire your potentiometers as shown below to ensure proper operation. NOTE: Do NOT apply more than +7 volts to the A/D inputs (pin 1 and pin 6) or you will damage the processor. Also, the A/D converter in the processor can only read up to 5 volts. To ensure protection for the processor, install a 6.2 volt, 1 watt zener diode (1N4735) to ground at each input as shown above at ZD1 and ZD2. (Do not use a 5 volt zener as it will start conducting somewhat below 5 volts and affect the linearity of the readout.) The 330 ohm resistors are there to protect the zener diodes in case of a high voltage spike on the line. If you are using our Relay board to interface to the CT-2 then the zener diodes and resistors are already there and the CT-2 inputs are protected. Special Note for wiring A/D inputs: We have discovered that the ground pin (8) of the DIN plug does not supply a resistance-free ground connection. This will not be problem unless you are using the A/D inputs on the connector. The problem can be solved by connecting the ground wire(s) in your cable to pin 8 AND to the shell of the connector. This prevents a lot of display "jitter" when displaying A/D derived values. Note the grounding in the partially assembled connector shown to the left.

**Use with Yaesu G-5500**
The DIN8 connector is configured to match the connections to a Yaesu G-5500 rotator control box's External Control jack. If you wire up two DIN8 plugs to match the pinout shown above, you can plug one end to the CT-2 controller and the other end to the G-5500 control box and you are ready to go. In this case the G-5500 supplies +12 volts to the controller board. Note that the G-5500 rotator supplies the correct voltages to the CT-2 A/D inputs.

**Using an H-Bridge for Motor Control**
If you are using DC motors for antenna movement then you can use an H-Bridge instead of relays to control the motors. An H-bridge is a device that controls the speed and direction of a DC motor, by routing current in opposite directions. It allows low-power control signals from the controller to drive higher-power motors. They also can use Pulse Width Modulation (PWM) for speed control, and include diodes to protect against inductive kickback. The CT-2 controller will work with certain types of H-Bridges and by using the jogging feature, true PWM speed control can be realized. When selecting an H-Bridge to use with the CT-2, several factors need to be considered: 1. Look for a full bridge device, not a half bridge. 2. If you want to control both azimuth and elevation motors with a bridge, look at dual H-Bridges. That will simplify the wiring. 3. When using a dual bridge, both motors must be powered from the same power source. 4. The bridges must be controllable with just two input lines for each direction (two for up/down and two for CW/CCW). 5. The bridges must stop the motors when both inputs are high as well as when they are both low. 6. The bridge input lines must be pulled high. If they are not then use pull-up resistors to assure the lines are high when not being controlled. We have tested the CT-2 with three different bridges, detailed below. One thing to keep in mind is that the bridge must be able to handle the stall current of your motor. It is a good idea to measure the stall current yourself so you are sure how much current capacity you need.
This is the Bojack L298N bridge, using the L298N chip. It has a substantial heat sink, and over temperature shutdown, and provision for over current control. Another nice thing is that it does not require a separate 5 volt input. It derives the 5 volt VCC from the motor supply. But it is only rated at 2 amps (with 5 to 35 volt motors). This would be my preferred bridge if it could handle more current. They are cheap at about ten dollars for a pack of 4. It is available in several places. Do a web search. Here is one: https://www.amazon.com/BOJACK-H-Bridge-Controller-Intelligent-Mega2560/dp/B0C5JCF5RS This bridge requires pull up resistors on the inputs. They are easily added on the bottom of the board as shown to the right. Note that the 10k pull-up resistors are wired to the two input pins of both of the two bridges. That is because the two bridges are paralleled to handle double the current. For normal operation four resistors would be needed. In this case I needed two separate bridges because the two motors use different voltages, 12 volts and 26 volts. So I used two dual bridges each wired in parallel, which also gave enough current handling to work with my motors. Going back to normal usage, the motor supply voltage is wired to the top two terminals of the left edge connector. The bottom pin is a +5 volt output that can be used for low current requirements. I just used it to power the pull-up resistors. The motors are then connected to the two 2 pin connectors.
This is a 7 amp H-Bridge, available from EBay, for about eight dollars. It is EBay Item 182484648130. It can handle 6.5 to 27 volts at 7 amps. Price is currently about 7 dollars The seller says it has L298 logic, but it does not actually use the L298 bridge controller. Instead it has a bunch of AND, and NAND gates to make up the same circuit. It works ok, but I don’t think it offers the protections that the L298 chip has (such as over temperature shutdown). Also it does not have any external heat sinks so I’m not sure how well it will handle long motor operations. The motors connect to the two black terminals at the top and the motor power to the green connector. Grounding either of the input lines will cause the motor to turn in each direction. To the right is shown the input connector and an example of the kind of connector wire you can use. This bridge requires +5 volts from an external source. It is applied to the like-labeled pins. There is an enable line that you can disregard, and the IN1 and IN2 pins. They control the motor connected to P3, are on are on the bottom side. The IN3 and IN4 pins are on the opposite side. Those four pins connect to the motor control lines from the CT-2 controller.
If you really have a big motor, you can use this 12 amp H-Bridge. It is available from Digikey for about 29 dollars. Here is the link: https://www.digikey.com/en/products/detail/dfrobot/DFR0601/10279757 It can handle motors from 6.5 to 37 DC volts, up to 12 amps. The connections are similar to the others, the motor supply connects to the middle bottom connector and the motors to the two 2 pin connectors on either side. It needs +5 volts for VCC and does not require pull-up resistors. Note the small label near the connector that shows which pins do what. Note that there are pins labeled p1 and p2. They are for PWM input but are not used with the CT-2, The CT-2 does PWM through the input lines, via the JOG control.

Back to Controller