Arduino 12v DC motor speed control - hardware

[czal112586]

Greetings! First post and still educating myself so please go easy on me. I have been building an experimental aircraft (Cozy MKIV) and am currently planning out my avionics and wiring needs. I am planning to run an oil heat exchanger to provide cabin heat during cold winters. I would like to use an Arduino nano (open to others as I don't feel it makes a difference for my use case) to control a 12v 7.5A gear pump (https://www.enginegearonline.com/4-gpm-reversible-gear-pump-12v-for-diesel-fuel-or-water-transfer/) via an on/off potentiometer (e.g. right turn on and then variable speed control through remaining rotation due to limited space on instrument panel). The pump will be transferring hot oil from my engine sump to the heat exchanger with the idea that variable speed will provide variable temperature control.

Questions are:

• In topics/forums I have seen so far, the DC motors used are typically quite small (hobby). Any recommendations on ohm rating for a potentiometer for my use case described above. Again, I am educating myself but since I will likely have the Arduino control the motor speed via motor control unit, not sure if OHM rating maters all that much. Could be wrong.

• looking at the following to use - https://www.digikey.com/en/products/detail/cts-electrocomponents/450T328S503A1A1/4733103?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=PMax%20Shopping_Product_Low%20ROAS%20Categories&utm_term=&utm_content=&gclid=Cj0KCQjwl8anBhCFARIsAKbbpyR86YM4ZDK3bB6DVh2EZWyF0W5pHZNRW5a_RHMKveIP9NGvCxbOhP4aAkd_EALw_wcB

• Assuming I will need a standalone DC motor control module to connect to the Arduino and handle the amperage. Any recommendations

• The Arduino will power up via main master switch connected to a 12v power bus (along with my other avionics) so assume I will need a buck converter to get down to 5v needed. Any recommendations? They seem to all be pretty much the same but looking for something with over voltage, heat, short circuit protection. Will protect the wires going in via standalone circuit breaker (1A).

I realize there are likely some more details needed to be able to provide appropriate feedback. Please let me know. Thanks in advance for you assistance.

[jim-p]

For the driver:

20Amp 6V-30V DC Motor Driver

[Railroader]

@czal112586

use an Arduino nano

Know that Arduinos are not certified for anything like that You want to do. Being a former private pilot and also designing control systems in the industry I would never go for a hobby design in a flying plane.
Regard the environment. It's shaking, it's exposed to the climate, humidity, air pressure changes.
I suggest using an at least industrial grade manual pump control.

[czal112586]

Understood. Not intending to use the microcontroller for any critical parts. If any components in the scenario I am describing fail, just means I'll be slightly cooler in the cockpit as this is intended for supplemental heat. Other parts are driven off of traditional (aviation grade) bus/breaker or solid state breakers with redundancy. That said, if you are aware of an industrial microcontroller that is rated for the environment, all ears!

[czal112586]

Thanks! Gotta ask, when it comes to the potentiometer for variable speed control, is there some guidance on how to appropriately size/select the pot OHM resistance/rating. An area I continue to try to educate myself on.

[Paul_KD7HB]

If your machine have vibrations, do NOT use a potentiometer with a carbon track. The slider will quickly wear a hole in the carbon track. Use a wire wound potentiometer. 10k Ohms is the usual value for Arduino projects.

[jim-p]

@czal112586

appropriately size/select the pot OHM resistance/rating

If it too low then you will draw more current through the pot and maybe exceed the wattage rating.
If it's too high you might have noise problems
10K is a commonly avaiilable value and is usually just right.
With pots, you get what you pay for.