The Art of Electronics called the 555 a kit of parts, and that’s probably the best overall description you can come up with. Inside, you’ll find a voltage divider producing references at 1/3 ...

He put the 555 and some other parts together to create his own L meter. The writeup includes the theory behind this meter, with an incoming AC source converted to a voltage by an RC network.

When a 555 timer is operating in Astable mode we obtain a pulse on ... The output wave obtained from pin 3 is shown with markings below The time axis T is measured in seconds and the Voltage axis is ...

The 555 timer IC acts as a comparator circuit, with pin 6 connected to the positive supply voltage and pin 2 connected to the LDR. When the ambient light level falls below a certain threshold, the ...