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Unread 02-01-2007, 17:49
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Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
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Re: Fisher Price Motor Replacement Gearbox

Quote:
Originally Posted by Greg Needel View Post
For ~$38 you get a digital encoder for the gearbox which mounts directly to the output shaft of the motor.
Just to be clear, the encoder mounts directly to the output shaft of the motor/gearbox (not the motor itself).

While we are taking about Banebot goodies, they also have a new divider board that takes the encoder output (128/rev???) and divides it down to whatever number of pulses per rev down to whatever you need (e.g. 32, or 16 or 2). It is also rumored to have a "direction" output. Both features help simplify the code and reduce load on the CPU.

And they have version for all three of the larger planetary gearboxes they sell 32mm, 42mm, & 56mm.

I have had home brew encoders fail enough times that I highly recommend that folks consider spending the $38 on these custom encoders if you need to keep track of speed and/or position. Actually, I have had high quality encoders fail often too now that I think about it... ...but the problem was always mine not the encoder: I somehow mounted them where the chain or whatever was putting too much load on the encoder shaft or where they came disengaged from the chain or belt -- the Banebot encoders totally eliminates these failure modes. Highly highly recommended.

Joe J.
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