Re: Spindle Relay Question

>
> DPDT relays are readily available on eBay - you need only choose one
> with contact ratings 50% over the typical current draw of your motor,
> and a coil suitable for the drive output of your computer.

DPDT solid state relays are something I have never seen.

Mechanical relays that are DPDT are a dime a dozen, well a couiple
bux anyway.

I am not sure how you propose to run the motor. PWM out of the PC and
PWM the SSR ?

For a few $$ you can buy a SCR driver for the motor (surplus center)
and that can accept your PWM as the speed source.

A single DPDT mechanical relay could be used to then reverse direction.

As was mentioned, the current and voltage must be zero when you open
the relay.

Some of the more elaborate SCR drivers for treadmill motors have a
tachometer, either a encoder type wheel or a single magnet as a
feedback device.

The ones I have seen have been seperate boards that accept your
setting for speed, look at the RPM and then adjust the output to the
controller as needed.

From the few units I've seen, they are labeled controllers and not
drivers. different than we are accustomed to for stepper and servo
drivers.

From my limited experiance, the controller needs a circuit breaker.
I've had mine trip a dozen times in an after noon. no fuses there.

And, I am very confidant in saying that unless you do have RPM
feedback of some sort, you will have wildly varying speeds.

Also, the ones I've pulled from treadmills have a matched inductor for
the motor. Not totally sure what part that plays in the control scheme.

If you check out the DART site about controllers, they have decent
manuals and describe the features of the common controller.





Dave