Cheap Motors
Saw these in an ad tonight - might make for a fun cheapie bot - http://www.mpja.com/02-17-15.asp?r=265527&s=35
Ad says "Reversible small DC motor with a 2.5in. Dia. X 1in. wide rubber tire. Rated: ~130RPM @ 3V/.15A No Load; ~275RPM @ 6V/.2A No Load. Plastic multi stage reduction right angle gear head. Solder terminals. For toys, RC trucks & cars, robots etc.
L: 3-3/8in. W: 2-5/8in. H: 2-1/2” WT: .14"
Pretty high RPM though...
Ad says "Reversible small DC motor with a 2.5in. Dia. X 1in. wide rubber tire. Rated: ~130RPM @ 3V/.15A No Load; ~275RPM @ 6V/.2A No Load. Plastic multi stage reduction right angle gear head. Solder terminals. For toys, RC trucks & cars, robots etc.
L: 3-3/8in. W: 2-5/8in. H: 2-1/2” WT: .14"
Pretty high RPM though...
Comments
https://www.sparkfun.com/products/13258
https://www.sparkfun.com/products/13259
The motors don't have any gearbox which makes them useless for driving the wheels. I've wondered many times how this set could be designed and manufactured without anyone bothering to test them.
I've attempted to write a review on the MPJA website but my review never showed up.
LOL! I bet. ;-)
Wonder if they always 'moderate' unfavorable reviews?
Phew, I started to panic looking at the MJPA site. They don't stock my favorite gearmotors anymore, but fortunately All Electronics still does. My highest recommendation, IMO every roboticist needs at least 4 of these on hand at all times for that next medium size robot build. http://www.allelectronics.com/make-a-store/item/dcm-351/24-vdc-gear-motor-w/turntable/1.html
They are high voltage (24VDC) and low current. Perfect candidates for being controlled by a cheap L298N h-bridge: http://www.ebay.com/itm/Dual-H-Bridge-DC-Stepper-Motor-Drive-Controller-Board-Module-Arduino-L298N-DX-/251654649555
My fav is a cheapo 3-speed Tamiya gear motor, which you can build in any of three ratios. Couple it with a matching Tamiya tire, of which there are several varieties to choose from. Then, replace the 3V motor with one of these:
https://www.pololu.com/product/1117/
Now you have a motor that can be easily driven with an H-bridge, and consumes far less current even at stall. An L298 works quite well with this motor.
More than $4 for a wheel/tire set (more like $10 or so), but worth it.
@ erco - digging the twin bot design avatar!