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Glossary of terms you will come across during your Phase 2 training.

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In digital electronics, outputs of circuits are either high or low. In an astable circuit, the output is constantly changing between high and low.

An astable square waveAn astable circuit is an electrical circuit that does not stay in one stable condition. If you were to monitor it with an oscilloscope, it produces a 'square wave', this is a digital waveform with sharp transitions between low (0V) and high (+Vs). Note that the durations of the low and high states may be different. The circuit is called an astable because it is not stable in any state: the output is continually changing between 'low' and 'high'.


During the induction phase of the course, you will be issued certain tools, Tools Issued on Repayment.

As of June 2014, the cost of these tools to you is approximately €300. This sum varies from time to time, as the prices of the tools fluctuate.

The cost of these tools is deducted from your wages over the durantion of the course, working out at €10 to €15 per week.

If you already have some or all of these tools, no issue and no deductions will be made.

You can see the most current prices of this and all the other items issued on repayment here...


This is short for 1 atmosphere, or 101.3 kN/m2 (expressed in SI units), or 14.7 psi (expressed in Imperial Units).

One atm is atmospheric pressure, 2 atm is twice atmospheric pressure.

Don't confuse this term with bar. They both measure pressure, but they are not the same.

1 bar = 100 kN/m2 = 14.5 psi

1 atm = 101.3 kN/m2 = 14.7 psi


This is the microcontroller chip at the heart of the Arduino Uno R3 board.

ATmega328 chip as used in the Arduino board


Pressure is defined as Force per unit Area.

In the SI, Force is measured in Newtons, and area is the product of multiplying a distance (length) by a distance (breadth), metres x metres to give us a basic area of 1 square metre (1m2).

So, the basic unit of any pressure is 1N/m2, also known as 1 Pascal, or 1Pa.

This is a very small unit of measurement for practical use, so when we discuss much larger pressures such as atmospheric pressure, we talk in terms of thousands of Newtons of force, or kN.

Standard Atmospheric pressure is 101.3 kN/m2. We know that atmospheric pressure is constantly changing, and any figure above this is deemed to be high pressure, and any figure below this is deemed to be low pressure.

Within the earth's atmosphere, we have air. Although we are not normally aware of this, air has weight. This weight of air exerts a downward force on the surface of the earth.

As we gain altitude, the column of air above us gets shorter, and so exerts less force on us.

Force, acting on an area, is, by definition, pressure. In the SI, force is measured in Newtons, and area is measured in m2. For convenience, we measure pressure in milliBars. Check out the animation and see how the atmospheric pressure drops from the normal at sea level (1013mb) to lower and lower figures as we gain altitude.

Flash video(Flash animation)


This is fuel that has been broken up into extremely fine particles (in a diesel engine, this is done by the injectors). The reason why fuel is atomised is to have a relatively large surface area for each atomised particle of fuelFlash video(Flash animation)

The only part of any fuel that burns is its vapour. The amount of vapour given off by a fuel is directly proportional to its surface area. If we had one large particle of fuel, this gives us a relatively small surface area. If we take the one big particle, and break it up into thousands of tiny individual particles (atomise it), then there is a huge increase in surface area.

This in turn helps the fuel vapourise, which, in turn helps the fuel to burn.


A typical attenuatorAn attenuator is an electronic device that reduces the amplitude or power of a signal without appreciably distorting its waveform.

An attenuator is effectively the opposite of an amplifier, though the two work by different methods. While an amplifier provides gain, an attenuator provides loss, or gain less than 1.

The PicoScope PP198 shown is a passive 20:1 attenuator. This means that a 20V signal at its input will appear as a 1V signal on the output. As the signal is attenuated, the PP198 allows voltages of up to 300 V to be measured. This particular attenuator has been designed to allow fuel injector and primary ignition waveforms to be measured using the PicoScope automotive kit.

Attenuators are usually passive devices made from simple voltage divider networks. Switching between different resistances forms adjustable stepped attenuators and continuously adjustable ones using potentiometers. Fixed attenuators in circuits are used to lower voltage, dissipate power, and to improve impedance matching. In measuring signals, attenuator pads or adaptors are used to lower the amplitude of the signal a known amount to enable measurements, or to protect the measuring device, say, for example, an oscilloscope, from signal levels that might damage it.

More about attenuators from Wikipedia


This is a vital part of the Kettering Ignition System.

This is where the primary windings are joined to the secondary windings.

This connection completes the circuit for any electricity generated in the secondary windings, allowing this electricity to jump across the spark gap and then to return to the ignition coil  and the secondary windings. This connection is essential, because, for electricity to flow, there must always be a complete circuit.

See the video at 4 mins 10 sec for further explanation.

The auto-transmformer connection in the Kettering Ignition Sysstem.

Website is here

AutodataAutodata's core business is the research, compilation and creation of technical information for use in independent automotive workshops for the repair and service of cars, motorcycles and commercial vehicles. Although most of these workshops are non-franchised, ranging from small garages to large groups, fast-fits and a variety of specialists, a growing number of franchised workshops also need information on other manufacturers’ vehicles.

Autodata covers a number of subjects including:

Technical data, vehicle identification, service adjustments, lubricants and capacities, ignition system, fuel system, tightening torques, brake discs and brake drums, repair times, wheel alignment, timing belts, timing chains and gears, tyre sizes and pressures, service illustrations, service schedules, service interval indicators, key programming, diagnostic trouble codes, engine management systems, pin data, trouble shooter, airbags/SRS, air conditioning, ABS, electrical component locations and wiring diagrams.

Autodata website

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Please note, if you want to contact the main Training Centre in Baldoyle, you need to ring 01-8167400.

If you want to contact the CP Fitters' Section, you can Contact Us by email,, or by telephone: 00 353 1 8167543 This number gets you through to the CP Fitters' Section, Baldoyle Satellite Unit.

Our Address is : Construction Plant Fitters' Section, Unit 116, Grange Way, Baldoyle Industrial Estate, Baldoyle, Dublin D13 CA48.
We operate in a satellite unit which is about 300 metres away from the main training centre. You can see the location of this unit here, in Google Maps. You can also Check here for directions to the Baldoyle Training Centre.

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