Arduino Laser Tag - Duino Tag

Step 2: Basics

Basics

Page to try to help the electronics noobs.

Some basics which are useful at several points in the design of the duino tagger.

R = Resistor
C = Capacitor
V = Voltage
I = Current


Using LED's
LED's must be used with a resistor to limit the current through them.
Choose the current the LED will work at
R = (V supply - V led) / I
Not: You will probably just be able to copy the resistor values I used.

Buttons
The buttons (triggers etc) in this project are assumed to give a low voltage when pressed. The standard circuit for this is show in the circuit diagram provided. 


Filters
R C (Resistor Capacitor) circuits can come in useful at a few places in duino tagger, either for smoothing out changes in the power supply voltage or to turn PWM signals into analogue levels, not as complicated as it might sound:

To use the water analogy for electricity and current the resistor acts like a narrow pipe (imagine a straw) only allowing slow water (current) flow. The capacitor acts like a big water tank / bucket. The low pass filter in the diagram acts like a straw and bucket combo: Even if you suddenly change the flow of water in or out of the bucket the level (voltage) will only change slowly.

Cut off frequency for low pass: f = 1/(2pi*R*C)