Introduction: How to Make an Universal DC Motor Speed Controller
Motors are everywhere where and we see them in every application.From Drills to Locomotives , from RC car to lathe machine everywhere there are uses of motors.
But the most important characteristic of the motor is ,the need to be controlled for a specific work is the speed of the motor .
Typically gears can be used to change speed , but sometimes it is not the solution . That time we need Electronic Control to control the speed of the motor.
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Step 1: Components
Here are the components required
- NE555 timer link:https://www.amazon.com/gp/product/B00K243MIQ/ref=a...
- Resistance 10k link :https://www.amazon.com/gp/product/B0185FGYQA/ref=a...
- Pot 100k with knob link : https://www.amazon.com/gp/product/B00XXH3PGS/ref=a...
- 0.1uF Ceramic Capacitor link https://www.amazon.com/gp/product/B008DFCUFW/ref=a...
- 100 uF Electrolytic Capacitor link :https://www.amazon.com/gp/product/B008DF9YNI/ref=a...
- Perfboard link:https://www.amazon.com/gp/product/B00ARTP1J4/ref=a...
- Heat sink optional
Step 2: Theory
The speed is related by the following equation
N = V - Ia Ra / kØ
So speed can be varied by changing
- Terminal voltage of the armature V.
- External resistance in armature circuit Ra.
- Flux per pole φ.
Armature resistance control method: This is the most common method employed. Here the controlling resistance is connected directly in series with the supply of the motor .
The disadvantage if the method is the power is wasted across the resistance. so it is a big no.
The second option is the terminal voltage variation.
we apply this here to control the speed. Variation is obtained by using a PWM signal
What is PWM ?
Pulse-width modulation (PWM),is a technique for getting analog results with digital means. Digital control is used to create a square wave, a signal switched between on and off. This on-off pattern can simulate voltages in between full on (5 Volts) and off (0 Volts) by changing the portion of the time the signal spends on versus the time that the signal spends off. The duration of "on time" is called the pulse width. To get varying analog values, you change, or modulate, that pulse width. If you repeat this on-off pattern fast enough with an LED for example, the result is as if the signal is a steady voltage between 0 and 5v controlling the brightness of the LED.
Step 3: Circuit
- Start by soldering two diodes in opposite phase with the pots two end terminal with aY shape structure given in the pictures
- Solder the NE555 on the board
- Solder the two screw terminal at two ends
- Connect and Solder pin 4 and pin 8
- Connect and solder pin 8 to VCC terminal
- Solder the middle of the pot to pin 3
- Solder the diodes to pin 6
- Solder A 0.1 uF Cap to the pin 6 with GND
- Connect pin 2 to pin 6 and solder
- Solder a 100 uF electrolytic capacitor with VCC and GND
- Solder pin 1 to Gnd
- Connect a 10k resistance between VCC and pin 7
- Connect the one end of the terminal to VCC and the other to MOS Drain
- Connect a diode in reverse biased condition to the other terminal
- Connect the gate to the pin 7
- Connect the Source to GND
- Connect pin5 and GND with a 0.1 uF Ceramic cap
Step 4: Sticking the POT to the Board
The next task is to stick the pot to the board .
This is done by simply using a double sided tape.
Then I cut the tape to shape it with the potentiometer's back.
Now the work is to peel the tape's other side layer and attach it to the board.
My pot was a bit small compared to the knob.
SO here is a TIP for it.
Use a glue stick and fill the knob will glue first and then attach the knob.
This work Great.
Step 5: Applying to Different Object
This has been tested on all sorts of motor and it works pretty well ,
There are lots of projects that can be built with this like
- Solder Fume extractor
- Table top fan
- POV Project
What will you do with it ?
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