Subject:
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Re: 3V motors
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 6 Aug 1997 16:01:02 GMT
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Original-From:
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Jeffrey Strauss Morehead <morehead@ece.utexas.*stopspam*edu>
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Viewed:
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1287 times
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I too had a problem with 3 volt motors. The issue is the height of the PWM
output. If you drive your motor function at 50%, then 50% of 9.6V is still
much higher than the 3 VDC for full speed. One way to get some resolution
is to modify the supply pin of the L293D to be 5 VDC instead of 9.6. There
are instructions on how to do this on the HB web site. This gave me some
resolution, but the best advice for anyone using the HB is to use 9.6 V
MOTORS!! I have started work on the Tyco ZIG ZAG RC car...it has 9.6 V
motors. I wasted a lot of time with those 3v motors, stick with 9.6 and
save yourself some trouble.
jm
On Tue, 5 Aug 1997 David.J.Dostal@lawrence.edu wrote:
> Mike,
>
> I had a similar problem and the solution is not to put a resistor in
> series with the motors. With the varying amount of current a motor
> draws, the voltage drop across the resistor will vary as well and the motors
> will not see a consistent 3V. Rather, a cheap way to accomplish this is by
> stringing diodes in series with the motor. Diodes have a (mostly) constant
> voltage drop across them, and enough of them in series with the motor will
> shave off 6V. If you want your motor to be bidirectional, then you need two
> diode arrays in parallel with opposing "pass" directions. Did that make sense?
> This is the easiest and cheapest way to regulate voltage, but it still has the
> problem of eating battery power. I'm not sure if there is any easy way around
> that.
>
> Dave
>
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Message is in Reply To:
 | | 3V motors
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| Mike, I had a similar problem and the solution is not to put a resistor in series with the motors. With the varying amount of current a motor draws, the voltage drop across the resistor will vary as well and the motors will not see a consistent 3V. (...) (27 years ago, 5-Aug-97, to lugnet.robotics.handyboard)
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