This instructable is for converting a field excited alternator into a self-excited one.The advantage of this trick is that you won't have to power the field of this alternator with a 12 volt battery but instead it will power-up itself so that you can use it as a normal self-excited home generator.
Also, this method doesn't involves any additional components like capacitor banks, dc generators or a battery.Its just a simple trick with wires.
You can directly watch the step by step video.
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Step 1: Things Needed:
Step 2: Mechanical Connections:
First we will do the mechanical connections and then we shall proceed with the electrical connections.
Take a DC motor of around 500W and connect a Pulley on its shaft.Now take a wooden board of 30 x 30 cm^2 and Mount the DC motor on one side of that board.
Take a vice big enough to Mount an alternator and place it on the other side of the wooden board.Use screws for mounting it properly on the wooden board and then Mount the alternator on it.
Take a belt to connect the pulleys of the DC motor and the alternator as shown in the picture.
Step 3: Electrical Connections (Alernator):
Rotor (field) - The red and the blue wires of the alternator are of the brushes which are connected to the rotor (field) with the help of the slip rings.Red is for positive and blue is for negative.
Armature - the big long screw of the alternator is the main output positive terminal and it separate from any other screw on alternator.
Connect the positive red wire from the brushes to the main positive terminal (long screw) of the alternator.
*Note - in the second picture, the red wire is not directly connected to the main positive terminal of the alternator since the red wire wasn't long enough.The screw to which I connected the red wire was indirectly connected to the main positive terminal (the long screw) of the alternator so it worked the same.You can without hesitation connect the red wire from the brush to the main long screw positive terminal of the alternator.
Connect the negative blue or black terminal of the brush to anywhere on the body of the alternator since its at ground negative.
Outside power source - take a 5 volt mobile charger and connect its positive wire to the main positive terminal (long screw) of the alternator. Connect its negative wire(usually black) anywhere on the body of the alternator.
Step 4: Electrical Connections (DC Motor):
You can use any mechanical rotating source to rotate the shaft of the alternator.
I have used a 100 volts DC motor because of which I had to use 2 laptop chargers.I connected them in series 20 volts + 15 volts making an overall voltage of 35 volts.
I used a 35V DC source because I didn't have a hundred volts DC source to run the motor at rated RPM and torque. Still i achieved around ~400rpm which was enough to self excite the alternator.
Step 5: Testing:
So anyways, after doing all the connections simply start you mechanical source (DC motor in my case).
After the entire system is in motion, simply disconnect the mobile charger & remove it.Your alternator is self excited now.
Take a multi-meter and connect its positive terminal to the main positive output of the alternator (long screw) and touch the negative terminal of the multi-meter to the body of the alternator it shouldn't get some voltage (~5V DC in my case).
At 1000+ rpm, an alternator generates 14.4V for charging batteries.The achieved RPM for my alternator was only ~400 because of which it generated only 5 volts DC but yes the self excitation project was successful.
So that was all for this instructable guys.
Full Video: https://www.youtube.com/watch?v=jwB1XdWH0NQ
Channel : www.youtube.com/creativelectron7m