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This is only a preview of the Performance Electronics for Cars issue of Silicon Chip. You can view 38 of the 160 pages in the full issue, including the advertisments. For full access, purchase the issue for $20.00. Items relevant to "Smart Mixture Meter":
Items relevant to "Duty Cycle Meter":
Items relevant to "High Temperature Digital Thermometer":
Items relevant to "Versatile Auto Timer":
Items relevant to "Simple Voltage Switch":
Items relevant to "Temperature Switch":
Items relevant to "Frequency Switch":
Items relevant to "Delta Throttle Timer":
Items relevant to "Digital Pulse Adjuster":
Items relevant to "LCD Hand Controller":
Items relevant to "Peak-Hold Injector Adaptor":
Items relevant to "Digital Fuel Adjuster":
Items relevant to "Speedo Corrector":
Items relevant to "Independent Electronic Boost Controller":
Items relevant to "Nitrous Fuel Controller":
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Addendum
Resistor Colour Codes
Resistors usually have their value shown as a colour code,
using bands of coloured paint. Each colour band is used to
represent a numeral or a decimal multiplier.
The bands are normally nearer one end of the resistor than
the other and they’re read from that end. They can have four or
five bands. With a 4-band type, the first two bands show the
basic value, while the third band signifies the “number of zeros”
(or multiplier). The fourth band (often spaced slightly further
away) shows the tolerance – ie, how close to the specified
“nominal” value the actual value is likely to be.
With 5-band resistors, the first three bands are used to show
the basic value. In this case, the fourth band signifies the number
of zeros (or multiplier) and the fifth band gives the tolerance.
Note that the “0” represented by a black third band on a
5-band resistor doesn’t mean it’s ignored. That zero is still
counted, so that a black third band followed by a red fourth
band means there are three zeros – the equivalent of an orange
third band on a 4-band resistor (see example).
Sometimes, a resistor’s body colour makes it hard to decipher
the exact colours of some the bands by eye. The best plan here
is to check the resistor value with a multimeter, before
wiring it into your circuit. The same applies if the bands
seem to be equally spaced from both ends, so you don’t know
which end to start from. Where there’s a gold or silver band,
though, this will help work that one out – these bands always
go at the end of the code.
4
7 000 5%
47kΩ 5%
FOUR-BAND CODE
1st Digit
2nd Digit
3rd Digit
Multiplier
Tolerance
0
0
0
1
1
1
1
10
1% Brown
2
2
2
100
2% Red
3
3
3
1000
4
4
4
10,000
5
5
5
100,000
6
6
6
1,000,000
7
7
7
8
8
8
0.1 Gold
5% Gold
9
9
9
0.01 Silver
10% Silver
27kΩ 1%
FIVE-BAND CODE
2 7 0 00
1%
Capacitor Types & Codes
There are five types of capacitor you’ll commonly meet in
electronics. Most of the differences between them are due
to their dielectric (the insulation between the capacitor’s two
plates).
One very common type is the metallised polyester, either
dipped in green-coloured plastic to become a “greencap”
(they can also come in brown and red) or potted in a small
rectangular box of “yellowish” plastic to become an “MKT”
capacitor. They typically range from about 1000pF (.001µF,
or 1nF) to 0.47µF.
Another type is the multilayer monolithic ceramic. This
type uses very thin layers of ceramic material (like porcelain)
for the dielectric, between thin layers of metal film. Called just
“monolithics” for short, it is common in digital circuits. Values
range from about .01µF (10nF) to 0.22µF.
For use at high frequencies and for values from 1pF to
1000pF, the ceramic disc type is usually best. These have
metal electrodes on either side of a small ceramic disc. As
the electrical behaviour of the ceramic tends to vary with temperature, they’re available with different types of temperature
coefficient. The “NP0” type varies least with temperature.
Last are electrolytic capacitors, often called “electros” for
short. These use a very thin layer of insulating metal oxide as
the dielectric but a small quantity of conducting liquid is used
inside to make electrical contact with the surface of the oxide.
Electros are made in high values – from about 0.1µF up to
10,000µF or more.
Capacitors generally have their value printed directly on them
160
PERFORMANCE ELECTRONICS FOR CARS
but it can be a bit tricky to work out their value, because a
coding system is often used. One code is similar to the resistor code, with two value digits followed by a third digit giving
the multiplier or number of zeros. So “104” decodes as 10
and four zeros, or 100,000. Similarly, “221” means a value
of 220. When this coding system is used, you can almost always assume that the value is in picofarads – so “104” means
100,000pF or 0.1µF, “103” means 10,000pF (or 0.01µF) and
“221” means 220pF.
Another code uses three digits followed by an “n”, and the
value is in nanofarads rather than picofarads. So “220n” means
220nF (or 0.22µF).
Low-value ceramic capacitors generally have their full value in
picofarads printed on them (eg, “15” for 15pF) or “47” for 47pF)
and might even have a decimal point (eg, “5.6” (for 5.6pF).
Electrolytics also have their full value on the case, along with
a voltage rating. Because they’re polarised, they also have a
band to indicate the negative electrode lead.
Other letters on the capacitor’s body may be codes for the tolerance. For example, K means ±10%, J means ±5%, G means ±2%
and E means ±1%.
siliconchip.com.au
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