In article ,
Ignoramus15363 wrote:

The switch 's resistance should be much less than the input impedance,
but big enough so as not to exceed the limit on current produced by
the CC terminal.

5k should most likely work and those are very common pots.

I put a 1k pot in my drive the other day and it works great.

That will be at the lower limit, but should be just fine.

VFD makers specify 2 watt pots for mechanical robustness, not electrical
load. Nor do you want machine vibration to cause the pot to walk.

One thing about the Forward-Off-Reverse switch: Do not make it too easy
to operate, or the machine may start when you accidentally brush the
switch. The classic scenario is that one is setting things up, and gets
chopped up when the machine starts unexpectedly. So use nice big and
clunky switches, even though the current is maybe 10 milliamps.

Joe Gwinn



On 2009-09-01, DoN. Nichols wrote:
On 2009-09-01, Gunner Asch wrote:

[ ... ]

Look in the wiring diagrams and it should show you what value the pot is
supposed to be.

Generally....0-5k...some are 0-10k, others are different.

Yes -- but these are common ratings.

This is not something to guess at.

If you do..you will never get it going fast enough...or ever get it
going, or ever get it going slow enough.....

Hmm ... that effect would be more if it were being wired and
used as a rheostat instead of a potentiometer. Normally, the VFD has
three pins for use with a pot. One is common ground, one puts out 10V
or 5V, and the third connects to the wiper. Usually, the output voltage
is capable of sufficient current for 1K, 5K or 10K, and what really
matters is the voltage which the wiper returns to the control input,
which should cover the same range with any reasonable value of
potentiometer. Go really too high, and you are likely to pick up noise
which will cause the speed to vary a lot at mid range settings. Go
really too low, and the 5V or 10V output can't provide enough current,
and the voltage will be too low so you can't get enough speed. But
anything from 1K to 10K should be fine -- with values beyond that
possibly encountering problems. But it is not a critical value.

Enjoy,
DoN.