Subject:
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Re: motor power problems
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sat, 25 Jul 1998 04:04:37 GMT
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Original-From:
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Fred G. Martin <fredm@%nospam%media.mit.edu>
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Viewed:
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1174 times
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in short, the answer is:
"you can't use 3 to 4v motors with the Handy Board."
basically, these motors are cheap toy motors that are incredibly noisy
from an electrical standpoint, plus they want to draw far more current
than the Handy Board's motor drivers can deliver.
your options are:
1. get better motors, ones rated for 9 to 12v with 1 ampere of
current draw (e.g., LEGO motors)
2. design your own motor driver circuit and run your 3 to 4.5v motors
from that.
just reducing the HB's batt voltage wont' do it, as you have found,
because of the noise problem inherent in these cheap motors.
fred
In your message you said:
> Hi, everyone. I recently bought a preassembled handyboard from the Robot
> Store in Hong Kong, and I'm having trouble with motor power. My robot
> frame has two motors that can run at 3-4.5V. I was planning to use 5AA
> Nicads as a power supply for the whole board (as suggested in the list
> archives), which should give about 5V or so to the motors. I'd planned on
> using PWM to run the motors at 3.5V or so for a good cruising speed.
>
> Here's what I found:
>
> - Any PWM setting high enough to run the motors at full speed was also
> enough to light the "battery" light and reset the Handy Board. I can run
> the motors at an unsatisfactory crawl -- about 2.25 V, according to my
> voltmeter -- but anything higher makes the board reset. This problem
> occurs even if I switch to an 8AA power supply.
>
> - Even though my program waits for the start button to be pressed before
> doing anything, sometimes the Handy Board starts up with both motors
> running, apparently at full power with no PWM. Since this leaves the CPU
> without enough power to run, the robot gets stuck in a full-speed-ahead
> state. This heats up the L293Ds and is probably terrible for the motors,
> especially when I'm trying to run the board off 8AA batteries. The robot
> is also liable to jump off my desk while I'm trying to program it.
>
> Has anyone had similar problems, and if so how did you solve them? I know
> there's a way to provide a separate power supply for the motors, but I'd
> rather not cut traces on the board except as a last resort.
>
> If I do have to use separate power supplies, would the Handy Board itself
> run OK with a 9V battery? At least that way I wouldn't have two bulky
> power packs to deal with.
>
>
> --
> Raphael Carter <anagram@chaparraltree.com>
>
>
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Message is in Reply To:
 | | motor power problems
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| Hi, everyone. I recently bought a preassembled handyboard from the Robot Store in Hong Kong, and I'm having trouble with motor power. My robot frame has two motors that can run at 3-4.5V. I was planning to use 5AA Nicads as a power supply for the (...) (26 years ago, 25-Jul-98, to lugnet.robotics.handyboard)
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