<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by saabfast</i>
Sorry to resurrect this but I have wired up a flashing LED in the manner recommended by stevie_a, using the permanent and switched live to the radio for connections. It worked in the garage (albeit the LED is fairly dim).
Having had the car out this w/e, I parked in the drive with the top down. Then, walking past, I noticed a clicking. I tracked this to the relay I put in to operate the aerial from the radio output terminal. Then saw that the LCD display on the radio was flicking on and off in time with the clicking. By chance I found that if I covered the flashing LED (located in the square plate on the top of the dash), the clicking and all stopped. Uncover it and it starts again.
Now, this may be another 'senior moment', and I don't pretend to understand electronics and black boxes at all, but how does the sun act on an LED to operate the radio and cause it to switch the aerial relay, if only for a fraction of a second, on and off?
Alan
Saab 9000 Stg 1
'81 TR7 DHC
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LED stands for light emitting Diode, a diode is a directional device which only passes current one way (usually) except when the diode becomes saturated by a high voltage and can then pass current the other way (this is called the zener effect). I suspect the sunlight is saturating the LED with light and allowing it to pass current in reverse direction which is effectively short circuiting the +ve to earth momentarily. The amazing thing is that it doesn't go bang as they are very delicate, do you have a resitor in circuit with the LED to reduce the current?
Dave
p.s. I have an electronics background[:)]
"Do or Do not, there is no try" - Yoda
1980 TR7 Persian Aqua Drophead.
1979 TR7V8 FHC in Pageant blue
Jaguar X Type in pillar box red!
