Motors
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What are Hobby Motors?
A motor is a machine which converts energy into rotating motion. The dictionary definition of motor is broader than that but when engineers and mechanics talk about motors they are almost always talking about rotating motion. There are different names for devices which convert energy into other types of motion.
The hub or drive shaft is the rotating output of the motor.
A DC motor is a motor that uses direct electrical current (DC) as the source of its energy. An AC motor is a motor that uses alternating electrical current (AC) as the source of its energy. AC current is the type of electricity provided by household wall outlets. DC current is the type of electricity provided by batteries.
A gear motor is a motor with an attached set of gears driving a secondary drive shaft. Practical motor designs result in motors that spin too fast for most uses. As a result, almost all gear sets are used to "gear down" the motor. The geared down drive shaft spins slower than the direct motor drive shaft. The geared down drive shaft also spins "harder". Motor speed is generally measured in revolutions per minute (RPM). Rotating force is called torque and for hobby motors is generally measured in inch-ounces or centimeter-grams. We will discuss torque more in a future chapter of this tutorial. For now, just remember that the higher the number the harder the motor turns. Gearing down a motor reduces its RPMs (speed) but increases its torque. Conversely, gearing up a motor increases its RPMs but decreases its torque.
Gears are generally contained within a housing that protects the gears from interference and which provides a bearing surface for the various gear shafts and drive shafts. The term gear box generally refers to the entire system of gears, shafts, bearings and housing.
When you apply energy to a motor it spins as fast and hard as its design allows for that energy level and output load. If you increase the energy supply it spins faster and harder. If you attach a load the motor will slow down. If you continue increasing the load it slows ever more until the motors capability to work is exceeded. When the extreme load causes the motor to stop it is said to be stalled. Reducing the load causes the motor spin faster. If you entirely remove the load the motor is said to be "free running" and operates at its maximum speed for that input energy level.
Because of the influence of the load, you cannot absolutely control the speed of the motor by controlling the input energy level. If you need to precisely control the motor speed you must consider the load. Because it is difficult to measure load, the most practical way to precisely control motor speed is to directly measure the speed. A device which detects the rotation of a shaft is called a shaft encoder. By counting rotations for a period of time you can determine motor speed.
A servo is a motor with a brain. Instead of blindly taking input power and working as hard as it can, it takes requests for specific movement and attempts to satisfy the request. Some servos accept speed commands and attempt to move at the requested speed regardless of load. Other servos accept location commands and attempt to rotate the output shaft to a particular position. A "servo motor" is generally a neat package of motor, gear box and regulating electronics. A servo motor has two inputs: an energy source for the motor and a command source to tell it what to do.
Where can I buy Hobby DC Motors?
Below you will find several different hobby motors which are available at ScienceKitStore.com.
For quantities over 5000 Motors, please send a quote request to info@ScienceKitStore.com.
DC Motor, Round, Metal Brush
Product Code: RE140RA
Low voltage, low current, round DC motors with metal brush provide smooth operation, low vibration and low heat. Recommended for toys, robots, models and small electromechanical devices.
1. Measuring Conditions:
1.1 Rated voltage: 1.2 V DC
1.2 Motor Position: To be measured with motor horizontally held.
1.3 Environmental temperature: 25±10°C
1.4 Environmental humidity: 65%±20%RH
2. Electrical Characteristics (At initial stage after 30 seconds run-in):
2.1 At No Load
2.1.1 Speed: 6000±12%rpm
2.1.2 220 A max
2.2 At Max Efficiency
2.2.1 Torque: 6.6 g.cm
2.2.2 Speed: 4481±12%rpm
2.2.3 Current: 0.5 A(max 0.8A)
2.3 At Stall
2.3.1 Torque: 26 g.cm
2.3.2 Current: 1.48 A(max 2.2A)
2.4 Direction of Rotation: CW (Clockwise when viewing from the output shaft end with positive voltage applied to positive terminal)
3. Mechanical Characteristics
3.1
3.2 End Play: 0.05~0.5mm
3.3 Operating Temperature: 0°C ~+45°C
1. Measuring Conditions
1.1 Rated Voltage: 1.2 V DC
1.2 Motor Position: To be measured with motor horizontally held.
1.3 Environmental temperature: 25±10°C
1.4 Environmental humidity: 65%±20%RH
2. Electrical Characteristics (At initial stage after 30 seconds run-in):
2.1 At No Load
2.1.1 Speed: 3500±12% rpm
2.1.2 Current: 140 A max
2.2 At Max Efficiency
2.2.1 Torque: 7.3 g.cm
2.2.2 Speed: 2593±10% rpm
2.2.3 Current 0.31 A (max 1.4A)
2.3 At Stall
2.3.1 Torque: 28 g.cm
2.3.2 Current: 0.9 A (max 1.4A)
2.4 Direction of Rotation: CW (Clockwise when viewing from the output shaft end with positive voltage applied to positive terminal)
3. Mechanical Characteristics
3.1
3.2 End Play: 0.05~0.5mm
3.3 Operating Temperature: 0°C ~+45°C
Motor with Lead Wires
Product Code: P56046
Basic DC motor with lead wires operates with 1.5 to 3.0 volts and runs at speeds of 4200-5700 rpm. Dimensions are 40 mm L x 21 mm D. Weight 22g (0.8 oz).
New design: Wires are connected using terminals and can be unplugged if needed.
The motor is RE140RA or similar.
Motor with Alligator Clip
Product Code: RE140RACLIP
Micro motor RE140RA with color coded alligator clip wires. This is a 1.5 volt DC motor that works with only one battery (any size AA, C, D).
DC Motor, Round, Precious Metal Brush
Product Code: RF300CA
Low voltage, super low current, round DC motors with precious metal brush provide smooth operation, low vibration and low heat. Used for CD/DVD Drives, Audio devices, Office automation, motorized toys, robots, models and small electromechanical devices.
DC Motor and Generator
Product Code: RE140SA
A strong motor that can also be used as a generator to create semi DC electricity. Strong magnets used in this motor provide an extra torque at the expense of some lower speed.
A pair of this may be used to demonstrate the conversion of electrical energy to mechanical energy and vise versa.
DC Motor, 8V, 2400 RPM
Product Code: RF370CA12
Low speed, Low current, medium Torque DC motor. Rated for 8 Volts DC; but it operates safely with 4.0V up to 12V. Please see details for more specifications.
Specifications:
Item Number: RF-370CA-12560
Operating range: 4.0 - 12.0 Volts
Nominal Voltage: 8
No Load Speed: 2400 rpm
No Load Current: 0.015 A
Max. Efficiency Speed: 1970 rpm
Max. Efficiency Current: 0.069 A
Max. Efficiency Torque: 16 g.cm
Stall Torque: 90 g.cm
Stall Current: 0.32 A
Body Diameter: 24.4 mm
Body Length: 32.5 mm
Shaft Diameter: 2 mm
Shaft Length: 10.5 mm
Weight: 50 grams
Contacts: 2mm x 3.9mm
DC Motor, 12V, 5600 RPM
Product Code: RF370CA15
Medium speed, Low current, medium Torque DC motor. Rated for 12 Volts DC; but it operates safely with 3.0V up to 12V. Please see details for more specifications.
Specifications:
Item Number: RF-370CA-15370
Operating range: 3.0 - 12.0 Volts
Nominal Voltage: 12
No Load Speed: 5600 rpm
No Load Current: 0.026 A
Max. Efficiency Speed: 4840 rpm
Max. Efficiency Current: 0.17 A
Max. Efficiency Torque: 25.3 g.cm
Stall Torque: 187 g.cm
Stall Current: 1.06 A
Body Diameter: 24.4 mm
Body Length: 32.5 mm
Shaft Diameter: 2 mm
Shaft Length: 10.5 mm
Weight: 50 grams
Contacts: 2mm x 3.9mm
Motor Clamp, Adjustable
Product Code: MOTCLMP1
Universal motor clamp/ Motor Mount/ Motor holder for small electric motors with diameter of 3/4 inch up to 1 inch. Includes adhesive backing for easy mounting on smooth surfaces.
Mounting Base for Motor or Syringe
Product Code: MOUNT
Mounting base for motors and syringes. Adhesive back for light applications and two screw holes for heavier applications.