Subject:
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Re: Aviation Tractor MOC
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 17 Jun 2002 13:39:45 GMT
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Viewed:
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1479 times
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There are two issues here.
1. Can the motors sustain more than 9 volts without damage?
If I was TLC designing motors for use by kids, I'd make sure there was a
large safety margin. New batteries are typically 0.1 - 0.2 volts above their
nominal 1.5 volts, so you can expect a set of six to run at close to 10
volts for the first few minutes. So I would imagine that the motor
specification must include sustained operation at 10 volts as a minimum.
Besides, I would be amazed if a mass produced motor could be designed in
such a way as to be highly reliable at 9 volts and subject to catastophic
failure at 10 volts, a mere 11% increase!
2. Are your motors really seeing 100% of the battery voltage?
Unless you run the motor directly from the battery pack, there will be
voltage drops associated with the control electronics either inside the Lego
RCX or some other brand of motor control device.
So I suspect that your 9.6 volt input to your control device is not actually
what the motors see on the outputs. I would estimate that the typical
internal loss will be in the 0.6 - 1.2 volt area.
JB
In lugnet.technic, Jennifer Clark writes:
> Another thing I've come across, especially with multi motors setups, is the
> requirement for the batteries to be delivering enough current. A 9V PP3 just
> cannot cut it, but 6 normal AAs in parallel are great. Another combination
> I've used recently to surprisingly good effect is 8 AA NiMH rechargables in
> parallel using a battery box from Maplin (about 70p). This gives a total of
> 9.6V and really shifts the motors; motor power goes up as the square of the
> voltage, so if you had previously been using 6 NiMH giving 7.2V, going to
> 9.6V makes a serious difference. Of course the motors are only rated at 9V
> so there may be some risk in this... I'd be interested to hear opinions on
> this.
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Message has 2 Replies:
 | | Re: Aviation Tractor MOC
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| (...) How about crazy adults with a thirst for more power? I used to run my old 4.5v motors with a 12v power source. They still work fine today ;-) -TJ (frequent sufferer of Tim "the Toolman" Taylor syndrome <insert manly grunting noise>) (22 years ago, 17-Jun-02, to lugnet.technic)
| | | Re: Aviation Tractor MOC
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| (...) actually (...) I tried it "raw" without any controllers onto the excavator handset compressor/controller and it was *seriously* better than the 8.4V PP3 I had been using before. Of course with the PP3 there will be current issues, but even so (...) (22 years ago, 17-Jun-02, to lugnet.technic)
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Message is in Reply To:
| | Re: Aviation Tractor MOC
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| Nice job Simon! I always like watching these machines at the airport too, did the spec sheets you received state what sort of horsepower and max speed these things have? As for the power problem, two 9V gear motors should be able to drive a machine (...) (22 years ago, 17-Jun-02, to lugnet.technic)
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