Subject:
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Re: motor voltages
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 23 Feb 1997 02:12:32 GMT
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Original-From:
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Matt Harlan <mjh10@=nomorespam=cornell.edu>
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Viewed:
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2317 times
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I
> have heard on this mailing list that there is a way to do this with a
> diode array. Can anyone refer me to a schematic in a book or just
> describe it well enough in ASCII?
Use a couple power diodes in series with the motor power supply, _NOT_ the
motor itself. You'll need pretty heafty diodes if you go this route. A
typical Si diode drops between 0.6 and 0.7 volts when forward biased.
String a few together and you'll drop 0.6 volts across each one. To go
from 9.6V to 6V you need 6 diodes. Measure the stall current for your
motors and get diodes that can handle at least that much current. If you
run them in series with the motor itself, they'll only go in one direction,
that's a diode for ya ;) You're better off using a seperate supply for the
motors. There's info on the HB web site for converting to two supplies.
It involes cutting a trace on the board and plugging in the new supply to
the motor power header, the four pin socket below the motor chips.
Now that I think about it, putting in diodes would be a real pain. You'd
have to cut the traces that supply the motor chips and splice in the diodes.
Hold on, new idea. Modify the board for two supplies, but use the diodes
to drop the voltage on the HB's NiCad pack and feed it into the motor power
header. Best of both worlds, only one battery pack and lower motor
voltage.
It should work, I think!
later
harlan
_______________________
Matthew J. Harlan
Cornell University
Electrical Engineering
mjh10@cornell.edu
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Message is in Reply To:
 | | motor voltages
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| Hello again, Thanks to all who responded to my query regarding motor chips on the Mini Board. Now that I have the more capable motor drivers installed, I want to lower the voltage that my motors see. They are getting straight 9V from the motor chips (...) (28 years ago, 23-Feb-97, to lugnet.robotics.handyboard)
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