# 200 Transistor circuits by Colin Mitchell PDF

## Introduction to 200 Transistor circuits by Colin Mitchell pdf.

This is the second half of our Transistor Circuits e-book. It contains a further 100 circuits, with many of them containing one or more Integrated Circuits (ICs). It’s amazing what you can do with transistors but when Integrated Circuits came along, the whole field of electronics exploded. IC’s can handle both analogue as well as digital signals but before their arrival, nearly all circuits were analogue or very simple “digital” switching circuits. Let’s explain what we mean. The word analogue is a waveform or signal that is changing (increasing and decreasing) at a constant or non constant rate. Examples are voice, music, tones, sounds and frequencies. Equipment such as radios, TV’s and amplifiers process analogue signals. Then digital came along. Digital is similar to a switch turning something on and off. The advantage of digital is two-fold. Firstly it is a very reliable and accurate way to send a signal. The signal is either HIGH or LOW (ON or OFF). It cannot be half-on or one quarter off. And secondly, a circuit that is ON, consumes the least amount of energy in the controlling device. In other words, a transistor that is fully turned ON and driving a motor, dissipates the least amount of heat. If it is slightly turned ON or nearly fully turned ON, it gets very hot. And obviously a transistor that is not turned on at all will consume no energy.

A transistor that turns ON fully and OFF fully is called a SWITCH. When two transistors are cross-coupled in the form of a flip flop, any pulses entering the circuit cause it to flip and flop and the output goes HIGH on every second pulse. This means the circuit halves the input pulses and is the basis of counting or dividing. Digital circuits also introduce the concept of two inputs creating a HIGH output when both are HIGH and variations of this. This is called “logic” and introduces terms such as “Boolean algebra” and “gates.” Integrated Circuits started with a few transistors in each “chip” and increased to whole mini or micro computers in a single chip. These chips are called Microcontrollers and a single chip with a few surrounding components can be programmed to play games, monitor heart-rate and do all sorts of amazing things. Because they can process information at high speed, the end result can appear to have intelligence and this is where we are heading: AI (Artificial Intelligence).

But let’s crawl before we walk and come to understand how to interface some of these chips to external components. In this Transistor Circuits ebook, we have presented about 100 interesting circuits using transistors and chips. In most cases the IC will contain 10 – 100 transistors, cost less than the individual components and take up much less board-space. They also save a lot of circuit designing and quite often consume less current than discrete components. In all, they are a fantastic way to get something working with the least componentry.

A list of of Integrated Circuits (Chips) is provided at the end of this book to help you identify the pins and show you what is inside the chip. Some of the circuits are available from Talking Electronics as a kit, but others will have to be purchased as individual components from your local electronics store. Electronics is such an enormous field that we cannot provide kits for everything. But if you have a query about one of the circuits, you can contact me.