Greetings Worldly Scions,
Wrt the recent discussion on voltage regulators / stabilizers:
This part is actually a voltage _de-stabilizer_. Due to
an error in the original design drawings, the letters "de" were
omitted from all further documentation. I believe [random-voltage-
de-stabilizer] was the full designation.
Rather than use 12V guages or a solid state regulator for the ~10V
required to run our guages; Lucas took the opportunity to devise a
much more sophisticated system. The "de-stabilizer" takes the nice
regulated output of the alternator and "chops" it into a pseudo-
square wave, with an average value of ~10V.
This system has many feaures:
- Extra wires, terminals, and small tin boxes to fill unused space behind
dash.
- A Thermo-electric device with parameters that vary with ambient
temperature.
- Mechanical contacts that can vary due to oxidizing or pitting.
- Electro-mechanical operating principle that can vary due to car vibration.
- At least 2 "temporary" operating modes when required (open or shorted)
- A randomizer feature where the device can feed either full voltage or
none to the guage supply circuit for random periods of time.
These features fitted perfectly in to the Lucas corporate philosophy.
When my Green Spit was about a year old, the guages randomly quit working
a couple of times. Alarmed by this, I checked the circuit diagram and
deduced that this "de-stabilizer" was the cause. I never got around
to checking it. The guages have worked fine for the last 15 years.
Insert the "de-" prefix into all references in your parts manuals and
you'll realize that this part is often mis-diagnosed as being faulty.
Hope this clears things up ;-)
Bob Sykes (s1500@aol.com) - - - __,@_\____
'78 Spitfires - -- }-0-----0->
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