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1. 03:28 PM - Re: Re: Cessna OV protection + DIODE across ALT side of Master Swith (Robert L. Nuckolls, III)
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| Subject: | Re: Cessna OV protection + DIODE across ALT side |
of Master Swith
At 07:35 AM 12/26/2015, you wrote:
>
>Does anyone have any info regarding the internal circuitry of the
>Cessna over-voltage sensor? I am wondering if this sensor's
>internal transistorized circuit contains the equivalent of the
>removed diode and therefore a separate diode is no longer needed for
>arc suppression at the ALT side of the master switch. Hmmm.
I proposed a latching ov sensor circuit
to Cessna about 1970 with a schematic like
this
http://tinyurl.com/7g7mn6l
I never manufactured any and was not involved
in the qualification so I don't KNOW that
the drawing cited above exactly matches what
went into the airplanes . . . but a technician
who once worked for Electro-Mech and manufactured
the device after Hopkins lost the job says it's
"real close."
The diode is not included in any of my drawings
because it is assumed that the REGULATOR already
has the usual diode from F to ground.
The diode was part of the original Cessna installations
because the alternator switch actually controlled the
field relay inside the electro-mechanical regulators
http://tinyurl.com/d7ln4mt
This relay was not fitted with the recommended
diode. When the electro-mechanical regulators
were replaced with solid state . . . the diode
became part of the regulator and no longer
necessary at the switch.
Bob . . .
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