Power Tools for Technical Communication:
Simple Illustrations


You'll need some training and practice before you can use software tools like AutoCAD or Adobe Illustrator to create technical drawings such as you see in operator manuals for equipment. However, there are plenty of things you can draw illustrating simple relationships between basic shapes.

Recreate the following text and illustrations in the software of your choice. You should be able to create the illustrations in Microsoft Word, Corel WordPerfect, Adobe Pagemaker or FrameMaker, or other mainstream software.

Project 1: Simple illustration of an ionization smoke detector

Ionization smoke detectors provide early warning of fire by detecting smoke in the air and activating an alarm. They are the most common form of domestic smoke alarm, beause they are small and cheap to produce and have a recommended operating lifetime of ten years. An ionization smoke detector consists of an exterior casing, power supply, alarm, and ionization chamber (see Figure 1).

Figure 1. Components of an Ionization Smoke Detector

Project 2: Illustration of the ionization chamber

The ionization chamber is a sealed unit with vents on the casing to allow air circulation. Inside the case are two metal plates separated by an air gap. A radiation source sits behind one of the plates, which has a hole in it to allow the radiation into the air gap (see Figure 2). A voltage is applied across the two plates, giving one a positive and the other a negative electrical charge. The radiation source used is usually a small amount (approximately 0.2 mg) of Americium-241 in the form of its oxide, AmO2.

Figure 2. Ionization Chamber

Project 3: Traditional market relationships in U.S. power generation

The traditional market relationships are shown schematically in Figure 1. This is still an accurate description of the links between wind and electric industry players for most of the United States. (Note that end-use consumers, although shown in Figure 1, do not play an active role in the traditional regulated market because they have no choice about either the electricity product they purchase or who supplies it. Their interests and preferences are theoretically represented by regulators and by consumer advocates.) In this industry model, competition occurs among energy generation alternatives, including wind and other green energy options. This competition is directly influenced by the regulatory commissions, and a utility’s product is largely determined through the regulatory process.

Figure 1. Traditional market relationships in U.S. power generation

Project 4: Flow diagram of an asthma attack

Biological Process of the Condition

Exposure to an allergen such as pollen causes sensitization of the airways. The tissue lining the airways (airway epithelia) produces signaling factors known as immunoglobulins that bind to platelets and white cells in the blood. Upon second exposure of the allergen, histamine is released by the epithelia, and an asthma attack ensues. The latter process, which is called a Type 1 hypersensitivity reaction, consists of two phases:

  1. Immediate response. White blood cells and platelets release histamine, causing contraction of the smooth muscle surrounding the airways (bronchospasm).
  2. Late phase response. Some time after the immediate response is a delayed, late phase which is often nocturnal. Factors produced in the first phase attract more white blood cells, in particular, eosinophils. The result of this cellular infiltration is an inflammatory response and swelling of the airway epithelium, followed by excess mucous secretion into the air passages and bronchospasm. This process is illustrated in Figure 1.

Figure 1. A flow diagram showing the late phase response of an asthma attack.

Project 5: Cross-section of a mock nuclear device

  1. With a little effort you can make a remote plunger around the RC servo, which will strike the detonator cap when you transmit the correct signal. Fix this to the detonator cap.

  2. Pack the space between the outer cylinder and inner tube with modelling clay. Colored clay is acceptable, but there is no need to get fancy at this point.

    Figure 4. Cross-section of the mock nuclear device.

  3. Seal the ends of the outer cylinder, making sure that the aerial of the RC servo is exposed. Use left-over metal to disguise the device as an everyday object, such as a large suitcase.

  4. Store this device in a safe place until you are ready to use it.


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