What is a 555 timer and how does it work?
The integrated circuit that we will be using in this chapter has been around since the 1970s and is still going strong today. You can see the 555 timer circuit in the following diagram:
LM555 Timer pin out
The LM555 has two modes of operation. For this project, we will be using it in astable mode. The word astable means unstable, basically with respect to an oscillator. Now, in some cases we do not want the circuit to be astable, for example an amplifier. In this case, astable is a good mode.
The pins have various functions, depending on the mode in which we are using the device. The functions are as follows:
- Pins 8 and 1 are always power and ground respectively.
- Pin 3 is always the output pin that we will use to turn the LEDs ON and OFF.
- Pin 4 is the reset pin. Pulling this pin low (to ground) disables the oscillator in astable mode. Essentially the output goes low and stays low.
- Pin 5 is the control voltage pin. By applying a voltage to this pin, we...
