For each BlinkLED, you will need the following:
1 ea Microchip 12F509 PIC Microcontroller (Mouser PN 579-PIC12F509-I/P)
1 ea 22 ohm, 1/4 watt resistor (Mouser PN 291-22-RC). I used a 22 ohm resistor in my prototype but any value between 22 and 220 ohms will work. It depends on the supply voltage you will be using, the voltage drop across the LED, and the forward voltage of the LED. You want to choose a value that will result in a current of 10 to 20 milliamps through the LED. As a rule of thumb, resistor value in ohms equals the supply voltage minus .5 volts minus the voltage drop of the LED divided by the LED current in amperes (1 milliampere = .001 ampere). For example, for a green LED which typically has a 2.2 voltage drop with a 3.2 volt power supply: R = (3.2 volts -.5 volts -2.2 volts) / .020 amps = 25 ohms.
Keep in mind that different colored LED have different voltage drops across them when lite. Typical values are: Green 2.2 volts, Yellow 2.1 volts, Red 2.0 volts, Blue 3.8 volts, and White 3.2 volts. You will have to increase the supply voltage when using Blue and/or White LEDs in order to drive them to full brightness.
1 ea LED. Just about any LED will work. For my prototype, I chose a green LED removed from a Christmas light string. These have a wide viewing angle because of the flat concave top.
Enter the email associated with your account and we will send you your username and a temporary password.
That's a pro feature!
Want to go pro?
First step is to sign up.
Already a member?" Login »