Subject:
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Re: Burning hot motor driver chips.
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 10 Nov 1997 23:02:49 GMT
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Original-From:
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MAR ERICSON <mar@cooper#Spamless#.edu>
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Viewed:
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1545 times
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What does "RC" stand for anyway? I don't think it's Radio Control...is it?
-----------
ericson mar
Master of Engineering Candidate
Project: Mobile Robotics
mar@cooper.edu
(212)353-4356
Department of Mechanical Engineering
The Cooper Union for the Advancement of Science and Art
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On Mon, 10 Nov 1997, Chuck McManis wrote:
> Anthony,
>
> As you've no doubt heard, RC motors take much more current than the
> Handyboard can supply. To control RC motors your only choice is to
> create a separate H-bridge to drive the motors. You can do this fairly
> inexpensively with power transistors (TIP125, TIP121) or somewhat more
> expensively with MOSFETs. I did the latter and have been successful at
> driving 15 amp motors with the Handyboard. There is a pretty simple
> circuit on my web page at:
>
> http://www.professionals.com/~cmcmanis/robotics/servo.html
>
> There are links at the bottom for the MOSFET version that I built up. If
> I remember I'll put the zip files with the gerber layouts if you want to
> send them to APC to have some boards made up. The only defect in this
> design (and the Home brew club here has built up about 40 of these) is
> that when the battery voltage drops, and the charge pump loses power,
> the MOSFETs turn off through their linear range and that can cause them
> to toast if they are in the process of carrying a bunch of current. The
> solution is to that problem is to add power via a separate battery (the
> MAX622 takes 20mA peak current) via pin 8. The circuit that works well
> is a battery tied to pin 8 of the 622 like so:
>
>
> +------------------> To pin 8 of MAX 622
> |
> |
> ---
> -------
> --- 9v battery
> -------
> |
> |
> +------------------> To motor power ground
>
> Using the circuit you will probably want a switch on the battery
> to keep if from draining when the robot is off.
>
> A more complete solution is in the works that uses the PR pin of
> the 622 to cut off power to the FET gates.
>
> --Chuck
>
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Message has 1 Reply:
Message is in Reply To:
 | | Re: Burning hot motor driver chips.
|
| Anthony, As you've no doubt heard, RC motors take much more current than the Handyboard can supply. To control RC motors your only choice is to create a separate H-bridge to drive the motors. You can do this fairly inexpensively with power (...) (27 years ago, 10-Nov-97, to lugnet.robotics.handyboard)
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