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Old 02-04-2003, 03:12 PM
actofgod actofgod is offline
Bit Surgeon
 
Join Date: Sep 2002
Posts: 216
Quote:
Originally posted by bdebde
Wouldn't it be easier to adjust the speed by changing motors or gears? If it is too fast with three cells, then just use two cells. Now if you could adjust the pot from the transmitter while driving (can you say proportional speed control) then it would be worthwhile.
At first, changing motors was the only way to change bit speeds. The problem with that is that it is expensive; if you wanted to buy every speed of bit motor, at about $7 a pop, you'd end up paying quite a bit more than the car itself cost. You still wouldn't have fully adjustable speed; you could only adjust speed in increments based on their RPM rating.

After the first (legendary) dual cell mod, another way of changing bit speed was born: increasing voltage. It effectively doubled (or tripled) the number of possible bit speeds, since each motor could operate at 1.2v, 2.4v, or 3.6v. It still required owning several motors if you wanted to adjust speeds, and otherwise it was generally not practical to go back from 2.4v to 1.2v again, since so much modification of the chassis had to be done.

This mod builds on the voltage concept and takes it to the next level: you no longer have to own several motors to change speeds (which is also a relief on the wallet). You can pick a nice, fast motor with a good balance between torque and speed, and after doubling or tripling the voltage can adjust the speed back down to slower speeds. The degree of precision possible is much greater than swapping motors; you can have an infinite number of speeds, including a wide range between the RPMs of the available motors that you couldn't otherwise reach. Swapping motors can get you close to the speed you want, but this can get you *exactly* the speed you want, whether it's matching the speed of another car or realizing that you need to take those corners at somewhere between a 2.2 and a 2.6 speed.. like a 2.4253 or so speed. : )

The next step in this evolution will be when, as you mentioned, the speed can be adjusted while driving. On page one of this thread, this was discussed in terms of a motorized potentiometer, but it is not currently feasible due to the size limitations. I'm very excited about the Proportional Steering/Throttle Emulator being worked on; it represents the end goal we're after.

As for difficulty: the more advanced you want your control to be, the more complicated it will be to achieve it. Swapping a motor is child's play. Adding more batteries is a little more complicated, but if you use the Layman's mod it's still easy. Adding a potentiometer requires adding batteries and having two wires where there once was one, a beginner to imtermediate level soldering job at the most. The Steering/Throttle Emulator looks to be the complicated of all, but that's what you'd expect from something that gives you full control.
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