Previously I made a DC motor Speed Controller, the design was good but it could be used with only 12 V motors.
Soon I needed to control 24 V motors, so I had to come up with a design I can use for the work. I saw it would be easy to use a 7812 with the 555 or a zener, but I wanted something very versatile, then decided to use lm317 as a voltage regulator.
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Step 1: Components
Lm317 : http://amzn.to/2qnSuAK
Heat sink :http://amzn.to/2oUemTI
10 k Pot : http://amzn.to/2pdbq7A
10 k Pot Knob :http://amzn.to/2qnPvbh
220 Ohm resistor http://amzn.to/2pH2VD5
Perf Board http://amzn.to/2oQUmAP
Screw terminal: http://amzn.to/2pduhzc
22 AWG wire : http://amzn.to/2oUhsXW
1N4007 Diode : http://amzn.to/2qgjzXe
Btw if you are like me, you can salvage the most items from electronic boards
Step 2: Adding the Resistor
Start by soldering the lm317 to the Veroboard.I had already attached the heat sink to the Lm317 with the help of m4 nut and bolt.
There are three pins in the lm317
2 V out
3 V in
Soldering the220 ohm resistor with Adjust and V out.A diode will be added parallel to the 220 Ohm resistor with the cathode toward the Adjust pin.Then take the 10 k pot and add it to solder it to Adjust and Ground
Step 3: Add the Capacitor
What are the capacitors for?
A 0.1 uF disc or 1.0 uF bypass capacitor is recommended to reduce the sensitivity to input line impedance.I have used 1 uF.
The adjustment terminal may be bypassed to ground to improve ripple rejection.A 10 F capacitor should improve ripple rejection about 15 dB.
The cathode of 1 uF capacitor connects to the V in and the anode to the Gnd
The cathode of 10 uF capacitor connects to the Adj in and the anode to the Gnd
Step 4: Add the Terminal and Flyback Diode
what is a flyback diode?
It is a diode used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted.
The cathode of the diode is connected to V in.
The anode of the diode is connected to V out.
Step 5: Lets Control
Adjusting the potentiometer changes the V out,
The minimum voltage will be 1.25V and the max will the applied voltage.The only drawback is the efficiency is not so great, Being a linear regulator it will change the voltage drop to heat, so you will need a good heat sink for higher voltages applied .
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