Please 'Boom' Responsibly As most of you have noticed, the noise ordinances have become much tougher lately. Most of this is due to idiots, yes IDIOTS, who drive through residential areas with their windows down while their system is playing at full power. To make things worse, the music they listen to has all sorts of foul language that's not suitable for small children, (who may be playing outside). There are even a few people, who are even beyond idiot status, that play their systems at full power through residential areas after 10:00 PM (when many people go to bed). I don't believe that this type of behavior is good for the industry. If the fines get too stiff, people will stop buying large systems. If this happens, more people will get out of car audio (who wants a mediocre system). People get interested in things because they're exciting. A deck and four 6.5" speakers are not going to interest many of the younger car audio enthusiasts. If car audio enthusiasts keep annoying more and more people, the fines will keep getting tougher. All of this will only reduce interest in the equipment that fuels the industry. If you want to listen to your system at full volume, get out on the highway where there's little chance of bothering anyone. When you get to a red light, turn it down. If the only thing attractive about you is your 'system', you have some work to do. Bottom line... Think about what you're doing. Think about other people. It's not the end of the world if you have to turn the volume down for a little while. |
Light Emitting Diodes (LED): An LED is a special semiconductor which emits light when current is passed through it. There are many different physical styles. The emitted color spectrum is usually very narrow. It can generally be specified as a specific wavelength in the electromagnetic spectrum. The emitted color selection is somewhat limited. The most commonly available colors are red, green, amber, yellow, blue and white. The red, green, yellow and amber have a working voltage of approximately 1.8 volts. You can refer to the data sheet for each LED to find the exact value. The actual working voltage is determined by the breakdown voltage of the particular semiconductor material. When using an LED in a circuit, the
exact working voltage is not extremely important. The
most important thing is the current flow through the LED.
The current through the diode must be limited by a series
resistor. An LED has a specified maximum continuous
current rating. Most LEDs can pass 20 milliamps
continuously without damage but it is not necessary to
use the maximum rated current. An LED will light with
much less current. The difference between high current
and low current will be the brightness of the LED. To
decide what resistor value is needed, you subtract the
working (forward) voltage from the power supply voltage
and divide that number by the desired current flow. Working voltage (Vf)=1.8 volts Desired current flow=15ma (.015 amps) Power supply voltage=12 volts 12-1.8=10.2 10.2/.015=680 ohms
A 680 ohm resistor will limit the
current to a safe level although I would probably use a
1000 ohm in a vehicle because the charging system voltage
would be higher than 12 volts. Any resistor between 680
and 4700 ohms would probably work fine. Choose a resistor
with a power rating greater than or equal to the power
dissipation given by the calculator above. The diagram below
shows the parts of an LED. You must also know that an led has polarity. This means that the positive and negative terminals must be connected correctly for it to operate properly. As you see in the diagram below, if the polarity is reversed, the LED will NOT light. If the reverse voltage is beyond what the LED was designed to handle, it may be damaged. Click on the 2 buttons in the demo below to see the LED operation with either polarity. The picture below
shows a few different styles. |
 |
If you find a problem
with this page or feel that some part of it needs
clarification, E-mail
me. This is a link to this site's home page. |
 |
