DC Motors card Potentiometer values?

[Boeing 747 Flyer]

Hi everyone,

Please may someone tell me what the value of Pots to be used with the DCMotors Card is? The manual does not say.

Kindest regards,

Jack:mrgreen:

[Perik]

Hello Jack

The value of the Pot is not so important but a 10K linear
seems to be a good choice.

The image is from an earlier version of the DCmotor (http://www.andare-ing.com/uploads/Manual_USBDCmotors_English.pdf) doc.

5050

[Boeing 747 Flyer]

Hello Perik,

I have an instrument that uses a 5K Pot for feedback. Would this be okay or is it too low a value (it's okay I assume because it is close to 10K).

Regards,

Jack

[Perik]

Jack,

Give it a try - I don't see any problem using a 5K.
I even believe it will give a better and faster "reading" using a lower value than 10K.

You could dig into the PIC 16C745 documentation (http://ww1.microchip.com/downloads/en/DeviceDoc/41124c.pdf) and get some early sleep ;-)

Though as long as we talk about slow turning Pot. (more or less static),
this should not be critical. The important part is to apply a voltage in the
0 - 5V range to the A/D input of the PIC circuit and with "only" 8bit resolution
that should give you about 256 different levels.

Use IOCPconsole with logging to verify the change/range while turning the Pot.

[Boeing 747 Flyer]

Hi Perlik,

Thank you very much for that useful information.

Since the instrument is DC Motor powered, and not Servo powered, the Pots are "forever turning" (ie turn through 360 degrees constantly). Any ideas on how these work as they are not the normal type you'd fine in, lets say, a throttle quadrant.

Jack

[Perik]

Jack,

Not sure but it sounds like a multi-turn Pot. which is quite normal in
many applications where you need a higher resolution.

You should look at the work done by for instance Edoardo (http://www.mycockpit.org/forums/showthread.php/20534-Airspeed-indicator-interfaced-with-OC-cards):