[vputz]

This isn't directly a CNC question, but it's related. I'm trying to make a microcontroller-based speed control for a Brent IE pottery wheel (for our meteorology department; they use it for a spin tank).

The wheel is powered by a KBLC-240D variable speed DC motor control, which is pretty much the same thing (I think) as the KBIC speed control in several Sherline mills (manual here).

The documentation says that I should provide 0-7V between P2+ and F- to enable voltage following, which [url=http://cnc4pc.com/Tech_Docs/KBIC.pdf]seems to agree with. However, I tried this (disconnected the control pot from P2/P3 and connected a bench power supply) and had no luck at all; the motor didn't even turn.

Any idea what I'm missing? I do want to point out that the motor control is wired differently from what I expected; instead of the pot being between P1/P2/P3, the low end (P1) is disconnected entirely making the pot act like a variable resistor instead of a voltage divider, which sounded strange. Additionally, P1 is jumpered somewhere with a resistor, which didn't match what I expected.

Any idea what I'm missing? Thanks--new to me, but once I can figure this out it should be a neat project.

[Al_The_Man]

I have not used the KBLC in this way but it doesn't seem to make much sense using the F- unless this is at P1 common also?
I have used the KBRG this way and it uses a COM terminal, did you try using an analogue signal between P1 & P2?
Al.

[vputz]

Al--

Hey, it seemed weird to me too, but from the manual:

Voltage Following – All models can be controlled with an isolated analog reference voltage (0 -7 VDC)
in lieu of the main speed potentiometer. The voltage is connected to P2 (+) and F-. The control output
voltage will linearly follow the input voltage. The source impedance of the input should be 10K ohms or
less. The Min and Max trimpots are rendered inoperative in the voltage following mode. Use auxiliary
trimpots for scaling and to limit the control range. If the input signal is not isolated, or is a current signal
(4 - 20 mA), the KBSI-240D or SI-5 Barrier Terminal Board Signal Isolator must be used. It will allow
direct connection to process controllers and microprocessors.

And the diagram right above it showing the KBIC used in follower mode showed several KBICs connected via P2 and F- . I can't make much sense of it; that just seems very strange to me. All I can say is I tried it and it didn't do a whole lot, and the only thing I can guess is that either mine's wired differently from the manual or I've got the wrong sort of voltage source (not sure what to make of the "10K ohms or less" line).