From: Ron Stygar <RonStygar_at_aol.com>
Subject: <all> Let's find the switches in the dark
Date: Thursday, 17 Feb 2000
Lighted switches let you find them easily in the dark. With the stock
switches in many cases you get an indication that the switch function is on
by a second light in the instrument console or by seeing the function caused
by the switch, happen.
I found some nice LED lighted switches at Mouser 1-800-346-6873
(www.mouser.com) that are available in all forms and in several colors. They
are available in round or square shapes. They are manufactured by Mountain
Switch. I prefer the round ones because they are always lined up. The
design current for the LED in these switches is 20 ma which is limited by the
value of resistor that you install in series with the LED. They have a
maximum current of 25 ma. You adjust the brightness of the LED by changing
the value of the in series resistor. The LED's in the switches are also
replaceable. The switch contact rating is 3 Ampere.
The first picture shows a switch wired so that you can find it in the dark.
This method is used when you can see the result of pushing the switch. One
example would be momentary switches to open your garage doors. Another is
switching between the V1 main module being lit to the remote display being
lit. I found that by killing the power to the remote unit, moved the display
lights back to the main unit.
This picture shows a switch wired so that when the function is energized
the lighted switch gets brighter so that you know this. An example of this
would be rear fog lights. The second pole of this switch shorts out one of
the in series resistors and the LED gets brighter. You adjust the ratio of
these resistors to your liking keeping in mind not to exceed the 20 ma spec.
Note that both of these resistors add up to the value of the single resistor
used for the find it in the dark switch. This is so that they match in
This picture shows a pair of switches mounted in the Z3 fog light switch
This picture shows the switches I added.
This picture shows the switches in the dark before I matched the red to the
The following shows the dimensions and part numbers for the various
Ron_at_unofficialbmw.com, FLI BMW, FLY BMW, Marlborough, CT
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