Digi-Key Employee Brad Scheie asked Luke Anderson and me if we could do a documented build of his handheld controller for his MinnKota trolling motor. The link to the video of the original controller can be found here:
He wanted us to publish this build on the TechForum because of the great response he got from his YouTube channel - where several viewers asked how to build it.
We looked at Brad’s controller and decided to improve upon his design by designing this controller with ingress protected parts and casing them in a waterproof enclosure. We wanted to develop this improved version because of its primary use in aquatic environments.
The original parts used in Brad’s controller were as follows:
CWI419-ND Rocker Switch DPDT (MOM off MOM)
RB141D1021-137-ND Rocker Switch (on off)
RV4N152C-ND Potentiometer 1.5k OHM 2W Carbon Linear
We decided to build a similar hand controller for a MinnKota 795MX trolling motor. We believe that this is an older version of the same motor that Brad was using in the original build. It also has more of a round style plug, unlike the flat one that Brad’s motor has.
Brad’s Trolling Motor Connector
795mx Trolling Motor connector
Before getting into the build, we wanted to find out how the foot pedal controller worked. We opened the foot pedal and removed the circuit board to get a better understanding of how it was desgined. Below is a picture of the board.
As you can see in the above picture, this control board doesn’t have many components. There are two resistors, a diode, three wire jumpers, a linear position sensor, and 5 tactile switches.
I then took a picture of the bottom of the board and traced out the leads with their corresponding wire color to better understand their connections. This drawing is shown below.
Reviewing where the traces led to gave us an idea of what the components were used for.
The switch at the top of the board is used for selecting either momentary or continuous operation of the motor.
The four switches on the bottom left and bottom right are used to reverse the direction of the turning motor which controls the direction of the motor.
The linear position sensor is used for controlling the speed of the main motor.
The blue resistor is used as a pull-down resistor for the position sensor.
The top resistor is used for limiting current to the positional sensor.
The diode is used as a flyback diode for the relay that is on the main control board of the trolling motor.
Next, we used a multimeter to check the total resistance of the positional sensor. The resistance of this sensor ended up being about 850 ohms. This sensor paired along with the other two resistors on the board total to just under 1400 ohms. Because of this we decided to use a 1.5K Ohm potentiometer. During the build, we tried with the resistors in place like the original circuit board, however, the additional resistors limited the amount of control we had over the speed. It also caused the motor to not come to a complete stop when the potentiometer was turned down completely. We opted to remove them from the final build.
The 4 switches on the bottom left and bottom right are used to change direction of the motor, and we realized that a DPDT switch could accomplish the same thing. If you need more information on how this is accomplished, take a look at this post on our TechForum Polarity Reversal using a DPDT Switch
In the foot pedal, the momentary/continuous switch works just like an on off switch, so we chose an IP 65 rated SPST on-off switch.
For our build we also wanted to eliminate the exposed automotive trailer connectors. To accomplish this, we chose a panel mounted IP 68 rated connector to fit in the box.
Lastly we tried to find a IP rated potentiometer, however we could not locate one with the correct specifications. To make the potentiometer more waterproof, we chose a rotary shaft seal to make the potentiometer as IP rated as possible.
Below is the list of components used:
|SC268-ND||Panel Mount 8 position Male connector|
|SC277-ND||Free-hanging Male 8 position connector|
|SC259-ND||Free-hanging Female 8 position connector|
|EG5120-ND||mom-off-mom DPDT IP67 16A rocker switch|
|CW137-ND||on-off Rocker switch IP65 20A|
|RV4NAYSD152A||Potentiometer 1.5K ohm 2W|
|335-1016-ND||ROTARY SHAFT SEAL GRAY|
|377-1118-ND||enclosure 4.528"x 2.559" x 2.165”|
|641-1310-1-ND||Diode 50V 1A DO41|
|WM13569-ND||Quick Connect 0.110” (2.79mm)|
|WM6238-ND||Quick Connect 0.250” (6.35mm)|
|https://www.digikey.com/short/pvmr7p||1 of these wire kits to make the connections|
If you are looking to purchase all of the components minus the wire, I have them all loaded in a cart located here: https://www.digikey.com/short/pv0fdn
You will also need:
- a soldering iron and solder
- heat shrink/electrical tape
- something to cut the openings for the box like a Dremel.
The first step is to cut the out the holes for your components. We used a Dremel for our cuts. The sizes of the cutouts are located on the datasheets or drawings for each of the components. The cuts were made freehand so not all of the cuts were the straightest. You will want to keep these as close to the panel cutout dimensions to try to keep this as water proof as possible. Luke took his time and made sure that the parts wouldn’t move once assembled. If you want to ensure the assembly is waterproof, we would also recommend using a potting compound to enclose the components.
To make wiring the controller easier, I drew a wiring schematic in Scheme-It. It is shown below.
This shows the wiring to the connector. We didn’t have any yellow or brown wire on hand, so we chose to use a blue and a second white wire. One the second white wire, we chose to use a yellow highlighter to differentiate from the other white wire.
For the free-hanging female connector, which connects to the cord that plugs into the trolling motor, we used SC259-ND. For mounting in the box of the controller we used part number SC268-ND. We opted to enclose this with a piece of heat shrink instead of the boot, however either could be used. The picture below is how the finished connector turned out with the heatshrink.
To make the foot pedal and interchangeable with the control box, part number SC277-ND was added to the foot pedal cable.
Below are some more pictures of the controller wired up. As a reminder, the connectors on the cable, that comes from the trolling motor, will be wired in the opposite direction from the keying in order to make the correct connections. Also notice the center pin is not used in this build.
The first connections we made in the controller was the black ground wire. We decided to do this because this cable has the most connections. We started by taking the black wire of the connector and another short piece of black wire and crimping them together into a 0.250” quick connect. This quick connect is then attached to pin 5 on the rocker switch. The next connection we made was soldering the new loose lead from the rocker switch and another short piece of black wire to the right terminal of the potentiometer. We also soldered the anode lead of the diode in the solder lug with the wires. Once this connection was made, we added a 0.110” quick connect onto the end of the new loose lead and attached it to the center quick connect of the on off switch. The below picture shows the connections of the black wire.
The next connection made was the orange wire. This connects to the opposite side of the potentiometer. The Cathode lead of the diode is also soldered along with the wire into the left solder lug of the potentiometer. Notice the band on the diode is to the orange wire side. Please reference above picture to see this connection.
The blue wire (brown in schematic) is the next wire attached. It is soldered to the center lug of the potentiometer. Please note that in the schematic, it is shown as a brown wire to match the color of the wire that is in the cable from the trolling motor. We didn’t have any brown wire, so we chose blue as a next best sub.
The white wire was the next connection made. We crimped a 0.110” quick connect on the end of the wire and it was attached to pin 1 of the on – off switch.
The next connection made is the red wire. Crimp a 0.250” quick connect to the end of this wire and attach it to pin 2 of the rocker switch.
For any questions on the above connections, please reference the photo after the explanation of the black connection.
The green wire is the next wire connected. Twist a second short piece of green wire onto the end of this lead. I then solder tinned the two wires together so they do not pull apart. Next I attached a 0.250” quick connect to this splice on the wire. On the new loose end of the short green wire, crimp on another 0.250” quick connect. Finally attach one of the quick connects to pin 1 and the other quick connect to pin 6 of the rocker switch. See below pictures for reference.
The yellow (or white with a yellow stripe in our case) wire is the last wire that is connected. This wire is similar to the green wire as you connect a short piece of yellow wire and the wire from the connector into a 0.250” quick connect. Also, on the loose end of the new short yellow wire, attach another 0.250” quick connect. With these two new connections connect them to pins 3 and 4. Below are pictures of this connection.
At this point the controller has all the necessary connections made. Carefully close the cover and install the screws to seal up the box. I had to slightly bend the quick connects to get the cover to fit properly.
Below is a video of the motor controller working.
New Controller on the left, Brad’s Original controller on the right
New Controller on the left, Brad’s Original controller on the right
The Finished Product