RE: [CAD_CAM_EDM_DRO] Spindle RPM control

Such chips exist, in fact they are quite common. Cheaper yet is a slow PWM
for speed command. Then you don't need a FVC, all you need is a resistor
and a cap to make a slow responding RC filter. I have done this in embedded
control to avoid the cost of a DAC.

GTJ

-----Original Message-----
From: RichD [mailto:cmsteam@...]
Sent: Thursday, September 26, 2002 5:27 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Spindle RPM control

CNC Idea!
RPM control of a spindle motor (controller) with a frequency to voltage
converter by using a spare axis CNC control program step output.
The rate is set in any block with the F word as needed.
The direction bit can control on/off/disable if wanted.
The FVC output will substitute for the pot in a typical PWM full wave
rectifier controller such as used in the Sherline machines.
The KBE controllers can be used in this manner.
This idea sort of is a poor mans constant velocity control or speed change
for various reasons in special cases.

Is this viable, plausible or practical?
I have not identified a VFC chip as yet. Do they exist?
RichD

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