The chip detects the rising and falling voltage on the capacitor. If a resistor is placed in series with the capacitor, the timing will increase. When a capacitor is connected to a voltage, it takes a period of time to charge. This is an external resistor and capacitor. They contain about 28 transistors, and the only extra components you need are called TIMING COMPONENTS. The 7555 comes as a single timer in an 8-pin package or a dual timer (7556) in a 14 pin package. The 555 comes as a single timer in an 8-pin package or a dual timer (556) in a 14 pin package. We call the TTL version “555” and the CMOS version “7555.” This is called ELECTRONICS JARGON. The 555 is also available as a CMOS chip (ICM7555 or ICL7555 or TLC555) and will operate from 2v to 18v and takes 60uA when the circuitry inside the chip is powered. This means it is not suitable for battery operation if the chip is to be powered ALL THE TIME. The circuitry inside the chip takes about 10mA – even when the output is not driving a load. It costs from 20 cents (eBay) to $1.20 depending on the quantity and distributor. It comes as a TTL 555 and will operate from 4v to about 16-18v. This IC is used in two different modes which are mentioned above.Download PDF book 50 555 Circuits NE555 by Talkingelectronics, the 555 is everywhere, and it is one of the cheapest and most-rugged chips on the market. It is a highly stable timer IC that can be used for producing accurate time delays and oscillations. When you need two 555 timers, you can use this IC as it has two timers inside a single package. The NE556 IC is a modified form of NE555 chip. Please check the datasheet given at the end for more information on specifications and features.

It has temperature stability better than 0.005% per ˚C.

The operating temperature range is from 0 to 70 degrees Celsius.It can produce a timing delay from microseconds to hours.TTL compatible output which can source or sink current of up to 150mA.

It is specified for operation from 4.5 V to 16 V.A dual version of NE556 consisting of two precision timers which operate in both monostable and astable modes.

Download free 555 timer pinout