This is my version of the breadboard walkthrough by Jklug80. Thanks for the intructions jklug. Anyway, I decided to add two more LED’s and I used 510ohm resistors instead of 330ohm simply because i couln’t find 330ohm in my house. I used a breadboard i bought at my local radioshack which cost me $14.99. The LED’s I utilized were ones that my dad had laying around. I took the wires out of a telephone cable and connected them to a 9v battery.the double-sided adhesive tape seen was just used to keep the wires attached so i could take the pictures. I know i have not made anything significant but this is my starting point into the realm of robotics. Hope you like!!
OK time to bust out the math: Red LEDs have a voltage drop usually around 2-2.2V, and your average ø3/5/10mm LED has a max forward current of 20mA. The nominal source voltage is 9V, and since each LED is in series with a resistor, any voltage not used by the LED will drop across said resistor giving you a maximum resistor voltage drop of 9V-2V=7V. The current flowing through the resistor is the same as the current flowing through the LED, and Ohm’s law tells us that the resistor current I=V/R=7V/510Ω=13.73mA. Since 13.73mA is less than the maximum 20mA limit, the LEDs will be fine. You could make them a little brighter by decreasing the resistor value a bit, but they should still run reasonably well.
You’re fine you wont blow You’re fine you wont blow the LEDs, but they could be brighter. Not a big deal but ALWAYS do a quick math check to make sure you dont blow your LEDs. It isnt a big deal with the single color LEDs, but the Tri Colors are $3 each at Radio Shack and still about 25-50 cents each off ebay when bought in bulk. It can get costly and annoying if soldered on perf board.
