🚀 go-pugleaf

In article <591@inuxh.UUCP>, rmrin@inuxh.UUCP (D Rickert) writes:
> Yup, many years ago I did a lab project in which we used a Decatron
> for motor speed control!  The idea was for the circuit to keep the
> same little dot continuously lit if the motor speed stayed constant
> at the set point.  A wonderful mix of analog, digital, and power
> technology.  I think we may have even had a mag amp somewhere in
> the circuit (you know, solid state Neanderthal style).

	Magnetic amplifiers!  I haven't run across those gadgets for servo
control in years.  They came in half-wave, full-wave and push-pull
configurations, and were particularly handy for military applications
which involved controlling 115 volt 3-phase 400 Hz motors.
	There is something used for motor control which is even older
than magnetic amplifiers -  the amplidyne.  This gadget was a close-coupled
[AC or DC] motor driving an AC generator (often 3-phase) with a DC field
coil.  Varying the voltage/polarity of the DC field controlled the resultant
AC voltage and phase relationship.  The amplidyne generator output then
drove a servo motor (usually 3-phase).  The amplidyne was popular during
World War II for controlling search radar antennas (PPI display).  Amplidynes
were well-described in the MIT "Rad Lab" series - which was still required
reading when I got my EE during the 60's.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
<>  UUCP:  {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry
<>  VOICE: 716/688-1231        {hplabs|ihnp4|mtune|seismo|utzoo}!/
<>  FAX:   716/741-9635 {G1,G2,G3 modes}    "Have you hugged your cat today?"