For this instructable (which is my first one, by the way) I will show you how to make a low cost transformer driver using an arduino and a few other components. Please keep in mind that I am only 10 years old, so if I don't explain something thoroughly enough, just let me know down in the comments and I will explain it with as much detail as possible. Also keep is mind I AM NOT responsible for any harm caused whatsoever. DO THIS AT YOUR OWN RISK!

Step 1: What You Need

arduino with a programming cable
1x 1K ohm resistor
1x BC337 transistor
1x Diode(make sure that it can handle the voltage and amperage of your power supply)
1x Breadboard (you can also use a proto board)
connecting wires
Power supply for transformer(for me a 9v battery worked the best.If you are using a battery, make sure you have a connector for it)
Patience for finding the right frequency
Computer with the arduino IDE installed on it (to upload the code)
Transformer that you want to run

Step 2: The Circuit

The whole purpose of this circuit is to transform the dc current into a pulsating dc current, which the transformer can use. The reason why it can't use normal dc current is because it has no frequency so it can't generate the magnetic flux the transformer needs to run. We are using the transistor to increase the voltage the arduino can handle so that it doesn't burn it out. The diode is to prevent back current when the transformer is turned off. The blue wires connect to the primary coil of the transformer that you are running.DO NOT PLUG IN THE TRANSFORMER YET!! Once you have built the circuit above(without plugging in the transformer), you can move onto the next step.

Step 3: The Code

Now it is time to upload the code to your arduino. Upload the code below.

#define control_pin 10
void setup()

{

}

void loop()

{

tone(control_pin, 1);

}

Step 4: Testing the Driver

Now it is time to plug in your transformer. Make sure the arduino is not plugged into the power supply yet or you can get ELECTROCUTED!!! Remember, the primary coil of the transformer connects to the blue wires. In case you where wondering I did put the circuit diagram picture on this step for reference. One the transformer is connected correctly, you can plug in the power supply to the arduino. you should here a quiet buzz or whine from the transformer, this is completely normal, if you don't here a buzz or whine that probably means that there is something wrong, refer to the trouble shooting page near the end of this instructable.

Step 5: Fine Tuning

The value that says 1 in the tone function can be changed to adjust the frequency that the transformer receives.

This is where your patience is needed! this can take a long time to get right!

Generally the smaller the transformer, the greater the frequency has to be. My transformer is from a 6 volt power supply for an old landline phone and the frequency only had to be 1 hertz. I also tried a smaller transformer and it needed about 6 kHz, which is a pretty big difference.

When you are fine tuning, remember to not have the power supply connected to the arduino, only the programming cable if you have both plugged in, your arduino will probably DIE. Once you have found the right frequency unplug the programming cable and plug in the power supply.

Step 6: Troubleshooting

If the transformer is not running at all here are a few things you can do:

make sure all of the connections are correct.
try flipping the transistor around so the emitter is now connected to the diode, the base is still connected to the resistor, and the collector is connected to the negative rail.
You may also have to swap around the diode so the cathode is where the anode is and vise-versa.
try replacing the transistor and/or the diode.
make sure the power supplies are supplying the right amount of voltage.
make sure your arduino isn't fried(don't worry, this project won't fry your arduino)
if all else fails replace your transformer