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[DPRG] thermal glue

Subject: [DPRG] thermal glue
From: David Peterson robodave1 at attbi.com
Date: Mon Dec 23 16:04:01 CST 2002

  Daryl, you may have a bit too small of an h-bridge to use on the motor if
the chip is getting hot from just free running. Usually each motor has some
type of number on it and a manufacturer. Of the type from Tanners that might
cause heat on a 754410 in free run, no load on the shaft, there are some
that resemble Johnson screwdriver/vacuum motors, that are about 2 inch in
diameter, maybe 3 inch long. These could have a stall that easily exceeds
the specs that the 754410 will drive. Specifics about what motor you have
could be really helpful, as in what numbers or markings are on the case.

  Also it may be possible that you have a litte miswire somewhere. A high or
1 or +5 should be to the 1,2EN enable, a high to the 1A input and a low to
the 2A input associated with 1Y and 2Y motor outputs connected to the motor
leads to turn one direction, reverse the 1A and 2A signals to turn the motor
the other direction.
   About using a ground plane, currently not an option using a wire wrapped
circuit. You are left with attaching a heat sink, possibly even wrapping
some bare wires over the sink and under the 4 ground pins only, for a form
of mechanical bond and a little additional heat transfer. Humming motors
aren't a bad thing, can just get annoying after a while.

----- Original Message -----
>From: "Daryl Gallatin" <dgall723 at mail.dal.devry.edu>
To: <DPRGlist at dprg.org>
Sent: Monday, December 23, 2002 2:28 PM
Subject: Re: RE: [DPRG] thermal glue


> Ok I will try that
>
>
> The 50hz PWM may be a problem too, like it has been suggested.
>
> I thought the motor was turning, when in fact it wasn't
> It was on, but not turning and the voltage ion both nputs on the motor
were approxiametly .25 volts. Like it was locked.
>
> I have tested it without PWM and just had a 1 to the enable pins, that
turned the motors(very fast) but it still got hot.
>
> SO I need to use a freq between 500hz and 5k?
>
> I had read that using it in the hearing range can cause the motor to hum
>
>
> My H0bridge, and opto isolators are wire wrapped. Is therea way to use
this ground plate?
>
>
>
> I do not have specs on the motors. I picked them up at tanners to use as
test motors.
>
>
> Thanks!
>
>


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