This Ebook is a handy reference for everyone who wants to learn how to use a CRO.
There are hundreds of different types of CRO's (Cathode Ray Oscilloscopes) on the market and we can not possibly cover them all. They range from hand-held (single trace) to dual trace and even complex types for specialized applications.
They all have lots of controls and buttons and at first they look extremely complex.
Buy once you know the basics of getting a picture to appear on the screen (called a TRACE on the display), you will be able to find your way around most of the layouts.
The important thing to do is not FIDDLE with the controls. It is very easy to lose a trace and more fiddling will make things worse.
Many times, when you first turn a CRO on, it will not produce a trace because it has been fiddled-with.
Your first job will be to set it up correctly and that's what this article will cover.
The second annoyance is the absence of "Frequency Markings" on a CRO.
It does not have markings such as: 25kHz, 1MHz or 10MHz to let you know the frequency of the waveform you are observing.
You have to work out the frequency by referring to the rotary switch called: "TIME/DIV" and look at the waveform on the screen. You will be trying to detect one complete waveform (called a CYCLE) and see if it fits between a single set of grid lines. With this information you can work out the frequency of the waveform, via our table on P 6.
There are lots of other things we will cover, and you will find this discussion to be very comprehensive.

There are three things you need to remember about a CRO:
1. It puts a load of approx 1M on a circuit. If you are measuring a waveform on a high-impedance section (such as 1 meg resistor) the amplitude of the waveform will be only 50% of the real size - the CRO forms a simple voltage-divider.
2. A CRO is generally described by the maximum frequency it is capable of displaying. Common values are: 10Meg, 20Meg, 50Meg, 100Meg, 250Meg etc. Some older types were 1Meg or 5Meg.
When a frequency equal to the maximum capability of a CRO is displayed, the amplitude of the waveform will be only 70.7% of the true value. This is due to the capacitive and resistive load of the input of the CRO. This is how the maximum capability of a CRO is obtained. You need to remember this when deciding which one to purchase.
3. The waveform detected by a CRO can sometimes appear to be different than expected. It may show distortion and spikes that can seem like glitches. The circuit may be rejecting these "faults" and it is very important not to be side-tracked by what you see on the screen.
That's why you need some experience interpreting the "picture" on a CRO.

In this Ebook we will be covering the following:

1. Explaining the meaning and operation of the main controls
2. Showing how to use a CRO to see what is happening at various points on a circuit
3. Interpreting the results correctly.
4. Explaining how some of the basic circuits respond to a fast-rising waveform (a square-wave) and a smooth-rising waveform, (an audio signal or sinewave).

By knowing some of these basics, you will feel much more equipped to:
1. Use a CRO in an electronics course and as a piece of test equipment on your workbench and/or
2. Buy one that is most suited to your application.

DESIGNING A PROJECT
When you are designing a project, one of the most important things is knowing the circuit is operating as expected.
Many circuits have been designed on the extreme edge of reliability and when they are constructed with non-identical components, they fail to work.
A CRO can help enormously in determining the reliability of a design.  By trying components of higher and lower value, the operation of the circuit can be observed.
Some circuits are very critical and others are very tolerant of component values and the CRO will help enormously in this area.
In all, you will find this Ebook most instructional.

MARKETING YOUR PROJECT
If you have an idea for a marketable project, now is the time to go one step further and start on the design.
You are not alone. There are thousands of inventors putting their ideas into reality and reaping the rewards.
Just go to your $2.00 shop or toy store and see the number of new ideas.
Someone is behind every one of them and if you knew the quantity produced, you would be astounded.
A simple hand-painted toy car collection-set requires a production-line of hundreds of workers to produce the thousands of items.
Don't only look at the mechanical toys, there are also lots of new electronic toys and gizmo's. I have just picked up a Chuppa Chub lolly with a Decision-making"  electronic game with flashing LEDs and mini speaker.
It contains a microcontroller chip, 6 LEDs, switch and mini piezo. All in a beautifully presented package for $2.00!
Instead of designing a cheap game like this, the microcontroller could be connected to a smoke alarm with a 2 second message such as "fire exit here."
The speaker can be connected to the alarm via 4 metres of wire and placed near the base of an exit door in a corridor.
All you have to do is make items such as this mandatory and you have sold millions.
If you don't, someone else will.


If you want to learn more about the skills of designing circuits, go to
TALKING ELECTRONICS Interactive website.
The site also has many projects in the FREE Projects Section, so everyone is catered for.
The subscription section contains a course on Basic Electronics and PIC Microcontroller Programming.
To subscribe, click HERE.

Colin Mitchell

12-03-2004