Subject:
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Re: Using the Motor as a Tachometer
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 9 Aug 1999 15:42:04 GMT
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Viewed:
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1073 times
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In fact, if you hook up two motors using the black cords and turn one of them,
the increased voltage will cause the other one to turn without any physical
effort applied to it. That's pretty rad.
I'm not sure if I understand the brake concept? Could you explain?
Nate Ridderman
nater@kconline.com
> > I'm not a EE, but here's my take on the situation...
> >
> > Turning the motor increases the electrical potential (voltage) between its
> > two contacts. If the motor isn't connected to anything, then its easy to
> > turn - relatively little energy is required to make one of the motor
> > contacts sit at a higher potential than the other. If you short the motor
> > contacts together, however, then you have a different situation. In order
> > to maintain a difference in potential, you need a sizeable current moving
> > through the wires. This requires a lot of work, thus its hard to turn the
> > motor. Thus how "hard" it is to turn the first motor has to due with how
> > much current needs to be moved in order to maintain a certain voltage.
>
> In fact, this is how the RCX motor controller internally sets the motor up
> for "brake" instead of "off"...
>
> Cheers,
>
> Ralph Hempel - P.Eng
>
> ------------------------------------------------------
> Outside of a dog, a book is a man's best friend.
> Indside of a dog, it's too dark to read...
> ------------------------------------------------------
> Reply to: rhempel at bmts dot com
> ------------------------------------------------------
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Message has 2 Replies:
 | | RE: Using the Motor as a Tachometer
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| (...) The brake concept can be easily demonstrated. 1. Hook up two motors to two separate RCX outputs. Put a big motorcycle wheel on each so you can see them spinning easily. 2. Hook up a touch sensor to one of the RCX inputs. 3. Program the RCX so (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
| | | Re: Using the Motor as a Tachometer
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| (...) A motor is just some coils attached to the shaft, which move through the field of a permanent magnet. When current flows through the coils, they become magnets and react with the permanent field. But I'm sure you already knew that. There are (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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Message is in Reply To:
| | RE: Using the Motor as a Tachometer
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| (...) In fact, this is how the RCX motor controller internally sets the motor up for "brake" instead of "off"... Cheers, Ralph Hempel - P.Eng ---...--- Outside of a dog, a book is a man's best friend. Indside of a dog, it's too dark to read... (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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