Trial for five speed stall.

[Trevor]

Originally Posted by Dessertrunner

Trevor the photos I posted this morning had a partial open photo. There were 4 photos 0 v was at rest position and then the next three had higher voltage and with each the valve opened a bit more. One of these images shows a intermediate position as you request and if you check the voltage metter you can see it is less then the voltage for the fully open valve image.
The pot size is not that big a issues as they only are used to check if my theory worked. They are 10K.

Sorry Tony I am unable to discern the variations in opening you describe from the four photos. I will try to get hold of a sample valve to examine.

I can not accept that you are able to use a dual pot. of 10k resistance (i.e. one normally used in an audio amplifier) as variable voltage control device, given the probable current involved. Mr. Ohm would back me up in this regard. It might be possible that it could be acting as a sort of switch, rather than as a voltage divider.