[TowerTalk] Ramp up

[Rick Mainhart]

Denis,

What you are looking for is a DC motor speed controller. These are rated
by horsepower and for a 90 volt DC motor can run off 115 VAC power.

The features you are looking for ... soft start and ramp stop are typical
features of these controllers. You may wish to look at Leeson, McMaster
Carr, W.W. Grainger, or your local motor shop. Cost can run around a
hundred dollars for a small (1/5 hp) well into the kilobuck range for a 5
hp unit with additional features.

If you want to homebrew your own ... you might look at pulse-width
modulating power MOS-Fet semiconductors set up in an "H" bridge
configuration. Model railroaders have been using PWM to give a more
realistic motion to their scale locomotives.

You may also enquire at your local industrial electronics repair depot
for bargains in used DC drives (another name for a DC motor speed
controller), or perform a net search.

Good luck & 73,

Rick, WB3EXR


On Tue, 07 Nov 2000 14:07:16 -0600 Denis Coolican
<dcoolica@planet.eon.net> writes:
>I drive a prop pitch rotator with a 90 volt DC motor.
>I was wondering if anyone  had any circuits or devices for controlling 
>a
>DC
>Motor.  I want to control the ramp up and ramp down on a motor 
>driving
>the propitch on the 5 element 20 meter beam.  I want to bring it up 
>to
>full speed in 5 secs and then, when I turn it off, I want it to slow
>down
>in 5 secs.
>
>That way I do not have have sudden starts and stops.
>
>I don't want to reinvent the wheel again, unless I have to.
>
>Anything on this kind of stuff for this homebrewer!
>
>
>Denis Ve6AQ / Ve6FI
>
>
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