I want to make a simple polarity reversing switch but I hadn't a switch with 6 legs like this one at Instructables. I had a lot of resistors and a small DC motor. Finally I used 2 pieces of 62R resistors and a switch. This is how it works

Step 1: How Does It Work?

I used two resistors with 62R. I connect each pole of the motor to +5V through a resistor. My first experiment with GND on right side of the circuit results the motor turns right.
During the second step the motor turns left.
So if I insert a switch I can turn the motor to rotate right or left.

Step 2: Some Calculations ...

I want to understand what happens so I started to calculate the paralell resistors value. You may find here a paralell resistor value calculator.

I tried with resistors 3R - 10R - 33R - 62R. They all worked but resistors lower than < 62R were warmed.
With 100R resistor it doesn't work.

The R3 resistance of the motor is 12R. So total I had 12R (motor) + 62R resistor = 74R.
Rtotal = (R2 + R3) * R1 / (R2 + R3) + R1 = (62 + 12)*62 / (62 + 12)+62 = 33.7

Step 3: The Polarity Switch

I measured the total resistance and there is some difference between theoretical and practical result (33R and 37R). But all in all the switch works and I made my XANAX.

Don't you know what xanax is?
It is a sleeping pill "developed" by the old man from Emir Kusturica's movie Promise Me This. Here is a sample on youtube.