How is made 555 timer.

                                                     555 Timer IC
 
    The 555 Timer is the one of the most versatile linear hybrid Integrated Circuit IC which is used in variety of pulse generation, timer and oscillator applications. In 1972, signetics Corporation first introduced this device as the SE/NE 555.
Commonly 555 has 3 operating modes 555 Timer
Now a days it is manufactured by many companies in bipolar and in low power CMOS. It is widely used in electronics circuits as it is very simple and cheap method to produce accurate and highly stable time delays. It can be used for various timing applications from microseconds to hours range and can source or sink up to 200 mA current.
When the output of 555 is HIGH current is sourced from the IC and when the output is LOW 555 is sinking current. It can source or sink current up to 200mA. If the load requires more than 200mA we can connect an external driver transistor for that.