Re: Fan Speed Controller

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Fan Speed Controller
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 4 Nov 1997 20:42:45 -0600
Approved: tesla-at-stic-dot-net

From: 	Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: 	Tuesday, November 04, 1997 10:03 AM
To: 	Tesla List
Subject: 	Re: Fan Speed Controller

> 
> I am looking for a low cost Fan Speed Controller that adjust a fan
> (1-phase, 120/240VAC, 3A, 50/60Hz) speed continuously according to an
> analog control signal (4-20mA or 0-5V).
> Any idea where I can find it and how much does it cost?

Carlo Gavazzi makes a Solid State relay type device that phase controls the
load according to a 4-20 mA control signal. It looks just like the standard
rectangular SSR. Newark Electronics carries them.  They run about $80.

If you want to build your own, get a Lutron (they are the best in fan speed
controls, even though cheap) fan speed control at the hardware store for
$5-10. It uses a single pot to control the speed. Replace the pot with one
of the LED/CdS cell optocouplers (Optron or Clairex). The curve is far from
linear, but it works.

By the way, 2 wire type phase controlled fan speed controls often need a
resistive load in parallel with the PSC motor or they go unstable at some
speeds.