 | | Using the Motor as a Tachometer
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I don't know if someone else has already written about this, if so, sorry about being repetetive. I was reading about hooking up 2 motors A + B and arriving at a dynometer arrangement. ie. Turning A causes B to rotate. I tried this, but also hooked (...) (26 years ago, 17-Feb-99, to lugnet.robotics)
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| | Re: Using the Motor as a Tachometer
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(...) Dave, this use of a motor as an input is fascinating! (How safe is it? Looking at some older threads, there seems to be a difference of opinions, or at least a non-consensus that it's safe...) I just hooked an 1x2 LEGO incandescent lamp up to (...) (25 years ago, 8-Aug-99, to lugnet.robotics)
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| | Re: Using the Motor as a Tachometer
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(...) 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 (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | Re: Using the Motor as a Tachometer
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(...) Try to short circuit the motor used as tarcometer / generator, and you'll see. Also try preventing the second motor from spinning, and you'll experience the same thing. About efficiency: this is not what you are experiencing, but the motor (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | Re: Using the Motor as a Tachometer
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(...) SNIP (...) SNIP (...) Todd, The danger as I see it is not electrical but physical. If the sensor mode of the input port is "active" the port will provide power to the motor (sensor). Thus you could have 2 motors either working together or (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | 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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| | Re: Using the Motor as a Tachometer
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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 (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | 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)
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| | 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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| | Re: Using the Motor as a Tachometer
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(...) A-HA!!! That makes sense! (...) No, this is great!!! Thanks! --Todd (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | Re: Using the Motor as a Tachometer
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(...) No way! Really? Too cool! Does it do this with some kind of switching relay or is it purely electronic? --Todd (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | RE: Using the Motor as a Tachometer
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Any rotating motor becomes an instant generator too...I use motors to power the fiber optic kit instead of using a port on the RCX or a seperate battery pack. An example is at: (URL) Thompson richone@midsouth.rr.com (URL) Message----- From: (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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| | RE: Using the Motor as a Tachometer
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(...) Totally electronic...but we used to do it with switching relays...use a non-proportional font for the following... /+---...--- V+ from power supply +--/ | +---+ +------+---+ | <- This is really a low value resistor --|MOTOR | | not connected (...) (25 years ago, 9-Aug-99, to lugnet.robotics)
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