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Integrated Circuits


Brief History


On Motherboard

Example: 4017B



An integrated circuit, or IC, is small chip that can function as an amplifier, oscillator, timer, microprocessor, or even computer memory. An IC is a small wafer, usually made of silicon, that can hold anywhere from hundreds to millions of transistors, resistors, and capacitors. These extremely small electronics can perform calculations and store data using either digital or analog technology.

Digital ICs use logic gates, which work only with values of ones and zeros. A low signal sent to to a component on a digital IC will result in a value of 0, while a high signal creates a value of 1. Digital ICs are the kind you will usually find in computers, networking equipment, and most consumer electronics.

Brief History


PN junction developed by Russel Ohl at Bell Labs



Transistor invented by William Shockley, John Bardeen, and Walter Brattain.



Integrated circuit concept published

English radar scientist Geoffrey Dummer published the concept of an integrated circuit in Washington, DC.



Integrated circuit invented by Jack Kilby at Texas Instruments.



Construction On Motherboard



Example: 4017B

The 4017B is an integrated circuit which has been designed to count pulses. It has 16 pins and looks like any other 16 pin integrated circuit.

They can be used in timing circuits and are often used to switch on and off LEDs or motors or other circuits. They are versatile and relatively simple to put together. Counters such as the 4017B are cheap and yet surprisingly useful.

The 4017B is most useful when combined with a timer such as a 555 based circuit. The pulse from the 555 timer can be used to activate the 4017B circuit.


A good example is Shown below. A 555  circuit is used to pulse the 4017B at regular intervals. The pulse from the 555 IC is generated from pin 3. In the circuit seen below, pin 3 of the 555 IC feeds into pin 14 of the 4017B (called ‘clock in’).


When this occurs pin ‘A’ of the 4017B emits current, lighting its LED. The next pulse from the 555 IC results in pin ‘B’ of the 4018B IC emitting current and lighting its LED.

4017B Integrated Circuit Description Schematic Pin Connections