motor control circuit

[primaryaccount@flashmail.]

I have an application where it is not possible to use a limit switch
to stop a drive motor on a chain driven turret.

What kind of circuit is used to detect that a motor, ac or dc, has
stopped and instantly cuts voltage to the motor. And then immediatly
allows the motor to be restarted with a switch in a forward or reverse
direction?

Thanks for the help.

 

[Robert Monsen]

<primaryaccount@flashmail.com> wrote in message
news:3f7f2d79.1866283@newsa.ev1.net...

I have an application where it is not possible to use a limit switch
to stop a drive motor on a chain driven turret.

What kind of circuit is used to detect that a motor, ac or dc, has
stopped and instantly cuts voltage to the motor. And then immediatly
allows the motor to be restarted with a switch in a forward or reverse
direction?

http://www.google.com/search?q=automatic+motor+reverse

 

[default]

On Sat, 04 Oct 2003 02:17:38 GMT, primaryaccount@flashmail.com
(primaryaccount@flashmail.com) wrote:

I have an application where it is not possible to use a limit switch
to stop a drive motor on a chain driven turret.

What kind of circuit is used to detect that a motor, ac or dc, has
stopped and instantly cuts voltage to the motor. And then immediatly
allows the motor to be restarted with a switch in a forward or reverse
direction?

Thanks for the help.
Current detection wouldn't work? AC and DC motors see a sharp rise in

current when they stall.

You would need to operate a latching circuit relay or electronic, and
let the new command override the latch. For start up there would need
to be some delay introduced to momentarily disable the current sensor
so it wouldn't just trip out again.


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[Ardent]

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primaryaccount@flashmail.com> wrote in message
news:3f7f2d79.1866283@newsa.ev1.net...

I have an application where it is not possible to use a limit switch
to stop a drive motor on a chain driven turret.

What kind of circuit is used to detect that a motor, ac or dc, has
stopped and instantly cuts voltage to the motor. And then immediatly
allows the motor to be restarted with a switch in a forward or reverse
direction?

I have seen in car window mechanisms voltage across a thick conductor
is monitored and when the motor stalls (when window hits the top) the
voltage drop increases and an opamp senses this difference and stops
the motor.

HTH

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Sandy Archer
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