How to control the speed of a DC motor?

Question

I need to control the speed of 1.5 V DC motor.. But don't know how to control it. Can i do it with some resistors, capacitors, and transformers??

Answer 1

It can be done with many different things. The easiest thing, since it is a low voltage motor, is a potentiometer. It will be variable speed but once you have it set it should stay pretty constant.

Answer 2

Both resistors and transformers will define the final drive speed of a motor. To the equation of FD = r * V
Where:
FD = a made up value for the rpm of the motor shaft.
r = resistance (standard)
V = Voltage (standard)

The motor is spinning at a speed dependent on the over all "power" (watts) it receives/uses. It will want to "use" all power available, to an extent. To control the 1.5V fan, firstly check you are correctly supplying 1.5V, then add a variable resistor to the circuit (calculate which values you need, and buy it from an electronics store, ones with Dials are called Potentiometers, or "Pots"), this will give you a dial to change the resistance, therefore slowing down or speeding up the motor.

You could also add a fuse to the circuit for a specified Wattage, determined by the max power you want the motor to use. If the motor burns out, it reduce it efficiency and effectively need more energy to spin at the original rpm, which with blow the fuse if correctly calculated.

Capacitors are not necessary, however a diode is needed to convert to DC, but your transformer should do that for you.

Good luck with the 'lectrics.

Answer 3

This depends how closely the speed must be regulated. Resistor may be ok for constant load, but a regulated variable power supply will give better results. Best method is to use a motor control circuit which utilizes a sensor to read the motor shaft RPM's and adjusts the motor drive voltage / current to maintain a preset speed.

There are some simple DC motor control ICs out there, used them in cassette decks, which work by voltage-current-torque, and are adjustable. Sorry I don't have any info., but hope this may give you an idea.

Answer 4

Guessing that you mean a DC motor running off of a 1.5 V. supply, but not drawing that load at correct speed, a simple current limiting resister would do the trick. This could be found experimentally with a variable res. and when the correct speed is found, it could then be replaced with a high tolerance fixed resister.
A simple governor could also be designed using an LED and an appropriate current limiting resister to compensate for the discharge curve if your 1.5 V source is a battery.

Answer 5

Low voltage drill controllers either use PWM or an op amp driving a power transistor to control the speed. With the op amp circuit the output voltage across the motor is fed back to the op amp so as to correct any voltage decrease.

Answer 6

Dear ma, Thank you, am also fine like you then dear in your took shunt motor it has 2 windings namely armature winding & field winding in that use armature control method i.e. apply fixed dc voltage to field (rated) & 0 - rated armature voltage to control 0 speed to base speed. The field current control is used to make the speed just above the base speed.

Answer 7

resistors silly i used a controller of an old style tyco mini car track one time to control a motor

Answer 8

Use a variable resistor

Answer 9

Yes

Answer 10

You can do it with variable resistor.