A major problem for common conventional motors is the presence of brushes, which limit the motor life and also create friction and noise. Brushless motors eliminate these disadvantages but in most cases they are more expensive and too complicated. The simple and inexpensive brushless motors shown on this site have quite good parameters even when they are compared to industrial motors.
The most impressive result in Stan’s experiments was achieved in the no-load efficiency test: one of the reed switch motors built from the kit worked non-stop over 50 hours on one 1.5 Volts AA size battery. This result is better than most industrial motors with comparable power can provide. To achieve this result the reed switch was moved slightly away from the rotor. The motor axles were lubricated with WD-40. The motor torque in this experiment was too low to do any real work.
These are some of the speed and current measurements for different motor types:
Your results may vary significantly as they depend on the accuracy of assembly, position of the sensor etc. For example, one of the Hall switch motors we built recently was rotating with the speed exceeding 4000 RPM on 6 Volts while another one achieved only 3100 RPM.
Due to a more efficient and precise design QuikLock motors built from the kits #13-14 may be even faster; in some experiments we achieved more than 7000 RPM on 6 Volts.
The last two motors in the table do not work on 1.5V and may not even start on 3V. If you want the motor with optical control to start on 3V or even less you need to make the blades of the disk wider. However, the motor will be less efficient and the transistor may become hot.
Stan’s load tests showed that the motors have quite large torque. With a string attached directly to the motor’s axle most of the motors lifted 75g on 6V. When the motors were connected to a speed reducer some of them were able to lift up to 4 kg (9 lbs) on 6V (the motor was slow, though). More about this experiment is described in Stan’s Project.
The motors may consume a significant current in case the rotor is stalled. This current is much smaller when the rotor spins at optimal speed. Large current may overheat the transistors and the electromagnet itself. This is why it is not recommended to exceed 6V in your experiments. However, if you have some experience in electricity and electronics, you may try higher voltages – most of the motors showed great results on voltages up to 12V. If you decide to do this, please, follow these recommendations:
- The rotor should be spinning all the time when you apply this voltage to prevent parts overheating.
- The power transistor may need a heat sink.
- It is not recommended to use higher voltages for the reed switch motors unless you use the ZNR. Reed switches normally do not work long on higher voltages because of the spark generated between its contacts.
- The resistor connected to the LED in the motor with optical control should have a greater value.