26-06-2012, 01:58 PM
1-100TransistorCircuits
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INTRODUCTION
This e-book contains 100 transistor circuits. The second part of this e-book will contain a further 100 circuits.
Most of them can be made with components from your "junk box" and hopefully you can put them together in
less than an hour.
The idea of this book is to get you into the fun of putting things together and there's nothing more rewarding
than seeing something work.
It's amazing what you can do with a few transistors and some connecting components. And this is the place to
start.
Most of the circuits are "stand-alone" and produce a result with as little as 5 components.
We have even provided a simple way to produce your own speaker transformer by winding turns on a piece of
ferrite rod. Many components can be obtained from transistor radios, toys and other pieces of discarded
equipment you will find all over the place.
To save space we have not provided lengthy explanations of how the circuits work. This has already been
covered in TALKING ELECTRONICS Basic Electronics Course, and can be obtained on a CD for $10.00 (posted to
anywhere in the world) See Talking Electronics website for more details: http://www.talkingelectronics.com
Transistor data is at the bottom of this page and a transistor tester circuit is also provided. There are lots of
categories and I am sure many of the circuits will be new to you, because some of them have been designed
recently by me.
Basically there are two types of transistor: PNP and NPN.
All you have to do is identify the leads of an unknown device and you can build almost anything.
You have a choice of building a circuit "in the air," or using an experimenter board (solderless breadboard) or
a matrix board or even a homemade printed circuit board. The choice is up to you but the idea is to keep the
cost to a minimum - so don't buy anything expensive.
If you take parts from old equipment it will be best to solder them together "in the air" (as they will not be
suitable for placing on a solderless breadboard as the leads will be bent and very short).
This way they can be re-used again and again.
No matter what you do, I know you will be keen to hear some of the "noisy" circuits in operation.
Before you start, the home-made Speaker Transformer project and Transistor Tester are the first things you
should look at.
If you are starting in electronics, see the World's Simplest Circuit. It shows how a transistor works and three
transistors in the 6 Million Gain project will detect microscopic levels of static electricity! You can look
through the Index but the names of the projects don't give you a full description of what they do. You need to
look at everything. And I am sure you will.
KIT OF PARTS
Talking Electronics supplies a kit of parts that can be used to build the majority of the circuits in this book.
The kit costs $15.00 plus postage.
In many cases, a resistor or capacitor not in the kit, can be created by putting two resistors or capacitors in
series or parallel or the next higher or lower value can be used.
Don't think transistor technology is obsolete. Many complex circuits have one or more transistors to act as
buffers, amplifiers or to connect one block to another. It is absolutely essential to understand this area of
electronics if you want to carry out design-work or build a simple circuit to carry out a task.
LED FLASHER WITH ONE TRANSISTOR!
This is a novel flasher circuit using a single driver transistor that takes its flashrate
from a flashing LED. The
flasher in the photo is 3mm.
An ordinary LED will not
work.
The flash rate cannot be
altered by the brightness of
the high-bright white LED can
be adjusted by altering the 1k
resistor across the 100u
electrolytic to 4k7 or 10k.
The 1k resistor discharges
the 100u so that when the
transistor turns on, the
charging current into the
100u illuminates the white
LED.
If a 10k discharge resistor is
used, the 100u is not fully discharged and the LED does not flash as bright.
All the parts in the photo are in the same places as in the circuit diagram to
make it easy to see how the parts are connected.
FLASHING TWO LEDS
These two circuits will flash two LEDs very bright and consume less than 2mA average
current. They require 6v supply. The 330k may need to be 470k to produce flashing on 6v
as 330k turns on the first transistor too much and the 10u does not turn the first transistor
off a small amount when it becomes fully charged and thus cycling is not produced.