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Typical Motor Specifications
For widely available general purpose motors that can be used with the Motor Control Wildcard

This page provides the mechanical and electrical specifications for some of the motors and speed encoders that may be used with the Motor Control Wildcard. These motors are useful for many robotics and automation applications.


Allied Motion CL66 Motor

The Allied Motion CL66 motor is often used to actuate peristaltic pumps. It's a 12V 30 W motor with the following physical and electrical specifications:

Part number Series 9904-120-13.111)
Nominal power 30 W
Nominal voltage 12 V
Nominal unloaded current 0.12 A max
Nominal torque 80 mNm
Starting torque @ 12 V 262 mNm
EMF @ 3000 rpm 12.8 V
Unloaded speed 2700 rpm (45 rps)
Nominal loaded speed 1800 rpm
Nominal loaded power 25 W
Nominal loaded current 2.1 A
Starting current 7.6 A
Internal resistance 1.5 Ω
Mechanical response time 25 msec2)
Rotor inductance 1 mH
Rotor moment of inertia 21.4×10-6 Kgm2
Datasheet Pump & obsolete motor datasheet
Allied Motion website
Allied Motion CL66 motor specs

The starting current is likely not needed for starting the motor, rather, it is the stall current drawn if the supply does not limit the current. If a limited current is supplied, the motor will still develop a torque proportional to the supplied current, and still start.

The motor is connected through a 5:1 gearbox to a peristaltic pump head, which turns at a rate of 10-400 rpm to pump 50-250 ml/min.

The following photographs show the motor (marked AIRPAX), with optical encoder on the bottom shaft and a 5:1 gearbox on the top shaft, driving a peristaltic pump head.

Motor with attached optical encoder and pump head
Pump head with attached motor and optical encoder.
Fig. 1  Allied Motion CL66 motor with attached 5:1 gearbox, peristaltic pump, and optical encoder.

US Digital optical encoder

The speed of the motor is monitored with a US Digital optical encoder (PN E5-32-157-NE-S-D-G-B). This encoder is a 32-quadrature cycle, 5 V logic output encoder iwth the following specifications specifications:

Fig. 2  US Digital optical encoder

The encoder cable pinout is:

Pin Color Description 10-pin connector on the Rev 2
Motor Control Wildcard 3)
1 Brown Ground 5 (ground)
3 Blue A channel 1 (pulse input)
4 Orange +5 VDC power 10 (+5 V)
5 Yellow B channel 2 (other pulse input)

The following table lists measured motor speed and encoder pulse rate (for a single encoder output) as a function of applied duty cycle at 12V and other supply voltages. The motor was unloaded except for the gearhead, peristaltic pump, and empty pump tubing. Note that this data provides the transfer function for the motor operated open-loop, without the Motor Controller Wildcard's PI control loop activated.

Voltage \ DC
Motor speed
pulse rate (Hz)
Pump speed
Pump flow4)
14V 100% 2756 1470 551 345
12V 100% 2343 1250 469 294
10V 100% 1933 1031 387 242
12V 10.3% 0 0 0 0
12V 13.8% 105 56 21 13
12V 20.7% 300 160 60 38
12V 31.0% 544 290 109 68
12V 41.4% 782 417 156 98
12V 51.7% 1043 556 209 130
12V 69.0% 1399 746 280 175
12V 79.3% 1674 893 335 209
12V 89.7% 1974 1053 395 247
12V 100% 2329 1242 466 291
12V 100% 2343 1250 469 294

These measurements are plotted in the following graph, with the data in this spreadsheet.

Fig. 3  Motor speed as a function of PWM duty cycle for a Allied Motion CL66 motor operated open-loop at 12 V with a 50 KHz PWM frequency.


Buehler Motor PN

This useful little DC motor is usually provided in an assembly with a speed reduction gear and slots for an optical encoder. Unloaded at 12 VDC it draws 55 mA and the output of the speed reduction gear spins at 51 RPM. The assembly comprises a brass worm gear driving a white plastic two-tiered gear, driving a 50 mm black plastic gear with a 8.3 mm plastic nib to provide reciprocating action, with a 1/2" radius of rotation on nib. The motor is 31 mm in diameter, 2 wire with two wires leads. The gears are mounted on a steel bracket. The overall dimensions are 5.5" x 3" x 2" high and weight is 340 gm.

Fig. 4  12 VDC Buehler motor with an attached gear set.
Measured motor current
Condition Applied voltage Current Speed
No load 12 V 55 mA 51 RPM
Stall 12 V 800 mA
No load 24 V 55 mA 104 RPM
Stall 24 V 1700 mA

Motor marked 93044-2909-12V-07623

This massive motor operates on 12 VDC and produces tremendous torque. Size is 4" x 2.3" diameter. Shaft is 0.31" diameter "D" type x 0.85" long. Has color coded 8" long flexible leads. RPM at 12 VDC is 2700 and current is 0.64 amps (no load). This motor was designed for automotive use and has brute force! It is marked with part number 93044-2909-12V-07623, (although in many descriptions on component shopping sites it is mis-marked 93044-2909-12V-0763). Weighs 1.7 lbs. This motor is available from Electronic Goldmine and Amazon.

Fig. 5  Large 12 VDC motor.
Measured motor current
Condition Applied voltage Current
No load 10 V 630 mA
No load 12 V 640 mA
Stall 6 V 3 A

The following graph shows the motor speed as a function of PWM duty cycle when operated unloaded with a 12V supply with power pulse width modulated at a frequency of 50 KHz. Note that when running open-loop stiction at the low end prevents the motor from spinning until sufficient power is applied, and the speed isn't perfectly linear with applied power. The graph also shows the motor speed as a function of commanded speed (0–100%) when the speed is closed-loop controlled by the Motor Control Wildcard. In that case, there is still a little deliberate dead band around zero to assure positive turn off.

Fig. 6  Motor speed vs duty cycle at 12V

Johnson HC683LG-020

This very powerful 10.8 V motor is intended for use in electric screwdrivers and similar tools. It is rated for a no-load current of 2.38 A and a stall current 105 A. Its maximum output power 275 W. The Motor Control Wildcard can drive it at light loads.

Fig. 7  Powerful high-torque motor used in electronic screwdrivers.
Measured motor current
Condition Applied voltage Current
No load 12 V 1.64 A
No load 4.1 V 1 A
Stall 4.1 V 2.2 A
Stall 5.5 V 3 A

9.68:1 Gearmotor

This small gearmotor is available from Pololu as PN 2271, 9.68:1 25Dx48L mm HP with 48 CPR Encoder. We purchased it from Jameco as Jameco Part no. 2205763.

Fig. 8  Small 6 V motor with integrated gearbox and Hall effect encoder.
Size 25D x 60L mm
Weight 3.35 oz
Shaft diameter 4 mm
Gear ratio 9.68:1 or, (22x22x24)/(12x10x10)
Free-run speed 1010 rpm at 6 V
Free-run current 450 mA at 6 V
Stall current 6000 mA at 6 V
Stall torque 17 oz·in at 6 V
Lead length 8 in

It has an integrated 48 CPR magnetic quadrature encoder on the motor shaft, which provides 465 counts per revolution of the gearbox’s output shaft. The quadrature encoder provides two square wave pulses, 90° out of phase, each 12 pulses per revolution, giving 48 total transitions per revolution. If the rise time of only one output is used, there are 12 pulses per motor revolution, or 116.16 counts per output shaft revolution.


Encoder and wiring

A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six color-coded, 11" (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch. The following table describes the wire functions:

Color Function
Red motor power (connects to one motor terminal)
Black motor power (connects to the other motor terminal)
Green encoder GND
Blue encoder Vcc (3.5 – 20 V)
Yellow encoder A output
White encoder B output

Slotted optical switch

Pin Use
1 Anode
2 Cathode
4 Output
5 Ground
OPB618 Specifications
Electrical Inv-Open Collector
Slot Width / Depth 0.150" / 0.240”
Lead Length / Spacing 0.100" (min) / 0.275"
Fig. 9  General purpose low cost slotted optical switch.
Fig. 10  Dimensions of the OPB618 slotted optical switch.

Taken from OPB618 datasheet.

This Airpax PN appears to be obsolete, but an Allied Motion datasheet seems to match it well.
For the original AIRPAX motor, may be 10-25 msec for a newer motor.
The pinout will be different for Rev 3 of the board
Assuming that the tubing is sized so that 400 rpm produces a flow of 250 ml/min.
This page is about: Typical Motor Specifications, for Widely Available General Purpose Motors that Can Be Used with Motor Control Wildcard – This page provides mechanical and electrical specifications for some of motors and speed encoders that may be used with Motor Control Wildcard. These motors are useful for many robotics and automation applications. Allied Motion CL66 Motor The Allied …