Page 201 - Engineering drawing from first principles using AutoCAD

194 Enqineerinq drawinq [rom [irst principles

sequencer distributing stored musical notes via two output flyers. Flyer 1 is connected
from port X to an eight-channel digital keyboard (Roland DS) which also has a built-in
drum machine. Flyer 2 is connected from port Y to a music arranger (Roland RASO),
which also has its own built-in drum machine, and to a digital synthesiser module (Kawai
I(IM). This synthesiser can play anyone of 128 sounds. All of the instruments play
together with backing rhythms.
The diagram is a useful exercise in setting out. Proceed as follows.

1. For Flyer 1, draw the vertical line and on the right side draw Smm lines at a vertical pitch
of Smm. You will find that the COpy feature can be used to copy two, then four, then
eight to give the 16 branches.
2. To the left use the TEXT feature in the Draw menu and one above the other draw the
numbers 1 to 16. These numbers need to be positioned at the same vertical pitch as the
branches, and this can be done using the MOVE command. When the item is selected,
click on the centre of the letter and reposition it centrally with the branch line.
3. Reposition the numbers 10 to 16 so that they are in a vertical line with the numbers 1 to
9.
4. The bracket from numbers 1 to 8 can be made from short lines and the FILLET feature.
Make one side and MIRROR the other exactly the same.
5. Ensure that the printed notes are positioned centrally and one above the other.
6. Use the ZOOM feature wherever possible.
7. Copy the numbers 1 to 16 and the branch construction below and add the notes applic-
able to Flyer 2.
The diagram on the right shows the audio connections between the instruments men-
tioned above together with a reverberation unit, tape recorder, amplifier and a change-
over switch for playback purposes. Take particular care in the positioning of the various
blocks to ensure that they are symmetrically spaced. Make one block using the
RECTANGLE feature and copy the others from it. I always write the text separately,
then piece it together and position it centrally within each block. Try to match the style
with any other notes appearing on the same, or adjacent, diagrams.
Where parallel lines are required these can be drawn automatically, but I find it easier to
use single lines with the SNAP feature for spacing. Their widths should of course be
identical. Clean up all corners with the TRIM and EXTEND features.

Heating systems

A schematic diagram of a basic heating system is shown in Fig. 9.9, where a boiler
circulates hot water through pipework to radiators and a hot water storage cylinder.
Central heating systems can be configured in many ways, but good thermostatic controls
are essential in every case. It is necessary to have flexible controls to turn the system on
automatically when required to heat rooms in use but without overheating them. The
system must provide adequate quantities of hot water, but not too hot, to prevent
scalding.

A house should be well insulated. It is often the case, though, that there will be only one
thermostat for the whole house, situated in the hall. If the hallway gets cool when the
front door is opened in winter, every downstairs radiator may then emit more heat than
is required. Heat rises to already-warm bedrooms, and roof insulation keeps it there.
Stiflingly hot bedrooms give rise to excessive fuel bills. Each radiator needs its own local
thermostatic radiator control valve (LRV) since bedroom temperatures are invariably
required to be lower than those in living rooms. Radiators in uninhabited rooms can also