Home  Sources  Part descriptions  Electrical parts  Mechanical parts  DC motors  Geared motors Gearmotors compared Nihon details Copal details Omron details Omron gearhead details Tokyo Micro details TS-53 details CS-20bb details Microcassette details BIObug 143:1 details BIObug 177:1 details BIObug II 224:1 details  Stepper motors  Misc. parts Assembly descriptions   BEAM Pieces is a BEAM Reference Library site.		Omron (Mac floppy drive eject) gearmotor detailed data All the data that's fit to print Manufacturer Omron Source Salvage; eject motor (Omron R2DG-38) extracted from Macintosh PC floppy disk drive; these drives are often available via Ebay or computer swap meets Comments These are good little motors for the price, if a bit bulky compared to some other options. Note that with a bit of patience, you can usually find surplus Mac floppy drives for $2-3 (US) on Ebay or at swap meets. These are very rugged and versatile little motors -- very good for walkers and tracking heads. Either a Sony internal or external floppy drive will yield the same hardware (so buy whatever's cheaper); only floppy drives for Macs have this motor, though. Meanwhile, here's what the floppy drive mechanism itself looks like: Floppy eject motors need to be "hacked" before you use them on a robot. I always cut off the cross-hatched pieces in the drawing above (just to minimize the motor's size). You definitely need to pry up the green circuit board and remove the small metal contact switch underneath it, as well as the one or two resistors on the circuit board. It's also cheap insurance to install a small (0.22 uF or so) filter capacitor in the resistor's place (across the motor's power leads). I have a detailed tutorial on all these steps elsewhere. These motors aren't quite as efficient as Nihon motors, but are very good for their size and cost. Since the starting voltage is relatively high for these guys (they're really not useable below 3.0 V), you'll most likely use these for battery-powered projects. This page presents all the data from my testing of two examples of the Omron gear motor salvageable from Macintosh floppy drives. The test procedure I used is described in detail elsewhere. I tested two copies of this motor in two configurations -- with only minimal modifications (removal of internal "limit switch"), and fully "hacked" (two internal resistors also removed). The resistors (2 x 470 Ohm 1/2 watt resistors) are there to provide "dynamic braking" when the limit switch is tripped; in the motor's original use (i.e., to eject floppies), this makes sure that the motor stops at the same position, repeatedly. We don't need this function, so the resistors' waste of energy doesn't buy us anything. What removal of the resistors does do is significantly increase the motor's efficiency, and decrease its current draw. But perhaps I should let the numbers speak for themselves... Motor "raw" (minimal mods): Voltage No-load Current (mA) No-load Speed (deg/sec) Efficiency (deg / mW-sec) 0.5 11.4 0 0 1.0 20.9 0 0 1.5 31.9 0 0 2.0 44.7 0 0 2.5 59 0 0 2.5 25 47.23 0.9157 3 28.5 75.9 0.8877 4 34.6 107.1 0.7738 5 41.2 142.3 0.6908 Motor "hacked" (internal resistors removed): Voltage No-load Current (mA) No-load Speed (deg/sec) Efficiency (deg / mW-sec) 0.5 9.3 0 0 1.0 18.3 0 0 1.5 28 0 0 2.0 37.1 0 0 2.5 50.3 0 0 2.5 15.1 62.9 1.6672 3 16 77.25 1.6094 4 18 109.76 1.5244 5 19.9 141.73 1.4244
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