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Parts explanation for 555 oscillator

Timer IC ( 555 )

There are a lot of second sources in 555 because the circuit is simple and is with a good performance.
The second source is the IC to be selling by the similar function from the other manufacturer. The pin arrangement is the same and it is possible to replace.
There is an energy saving type of the CMOS, too.


As the resistor, I am using the type that the permission electric power is 1/8 W. More than 1/8-W resistor can be used, too. In the case, the size of the resistor becomes big. This time, 1/8-W resistors are used to make a circuit compactly.


A multilayer ceramic capacitor is used for the capacitor to decide an oscillation frequency. The capacitor with good temperature characteristic should be used for this capacitor. The capacitor with good temperature characteristic is the capacitor where little change of the value occurs even if the ambient temperature changes. The polypropylene capacitor is a capacitor with good temperature characteristic. However, the precision of the oscillator doesn't become good even if only the temperature characteristic of the capacitor is excellent.

IC socket

The IC can be put to direct to the printed board, too. This time, a socket is used.

Printed board

I cut an universal printed board according to the space of the circuit.


I used studs as the leg of the printed board. The plastic spacer can be used, too.
It is to prevent printed board wiring side's touching the metal which was put below.

Wiring terminal

This is the terminal to connect a power line and an output line. It is possible to wire directly to the printed board without this terminal.