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When compared to the applications of an op-amp in the same areas, the 555IC is also equally reliable and is cheap in cost. It is basically a monolithic timing circuit that produces accurate and highly stable time delays or oscillation. That’s why we call it a “ 555.” (triple).The 555 timer IC was introduced in the year 1970 by Signetic Corporation and gave the name SE/NE 555 timer. When the chip produces an output frequency above 1 cycle per second, (1Hz), the circuit is called an OSCILLATOR and below one cycle per second, it is called a TIMER.īut the chip should not be called a “ 555 Timer,” as it has so many applications. This is called a “ONE-SHOT” or MONOSTABLE OPERATION. We can also do other things with the chip, such as “freezing” or halting its operation, or allowing it to produce a single HIGH-LOW on the output pin.

When the voltage on the capacitor is 2/3 of the supply, the output goes LOW and when the voltage falls to 1/3, the output goes HIGH. 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. 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.