Ed Anderson wrote:
Paul,
I fly with the Mazda alternator with internal regulator. >I placed
a
5
amp circuit breaker in my field coil circuit to pull and >disable the
alternator should it malfunction. So far no malfunctions, but >pulling
the
CB does disable the alternator output.
Ed Anderson
So it is not a true one wire alternator with the field fed >internally?
What year is that Ed?
Paul Lamar
Ed Anderson wrote:
Correct, Paul.
There is a wire that feeds the field coil (CB in this one), >one that is
used for the idiot light, and the large one for the Output voltage, so
three
altogether. Mine is a Bosch alternator remanufactured for the >Mazda RX-7
1986 vintage. Thus far it has stood up well.
Ed Anderson
This is exactly what I have on my LE, using a NipponDenso alt from an
85ish Honda Civic. I feed it 12v for the field via my "ALT" half of my
master switch (Cessna type) thru a 2 amp fuse. I, too, have verified that
I can shut off the alt in flight. Also have a 60 amp CB in the >output line,
and am using the idiot light connection for an idiot light (what else?).
Bill Freeman
For all interested,
Issue 46 of "Contact Magazine" has excellent article
on converting the Mitsubishi alternators commonly used
on 86-91 RX7(and perhaps 93+ RX7 and Cosmo 20B)to either
stock internal reg with external shutdown or external reg
and shutdown.The article also includes the same info for
some Nippondenso alternators.The Mitsubishi is said to
be the better design and easiest to convert.
Kelly Troyer
--
Mark Steitle wrote:
I was just looking at my 90A Mazda alternator and feel I have discovered how to disable the internal regulator in order to convert to an external regulator. However, it would be reassuring to read up on it before I take the wire cutters to things. Can someone summarize the Contact article, or tell me how to get a copy of the appropriate issue?
I read up on Bob Nuckolls' Aero-Electric book to find out why I would want to convert to an external regulator system. Bob states that the benefit in switching to the external regulator is to replace the "switching" regulator with a "linear" regulator. He states that he is unaware of any automotive alternator/regulator that is of a linear design. He sells a linear a/c regulator with a "crowbar overvoltage protection" circuit that will cut out within 5 miliseconds in case of an overvoltage type failure. That should prevent one frying their expensive avionics. Sounds logical to me.
Mark Steitle
I might add the drawback to a linear regulator is less efficiency and as a result
increased heat dissipation in the regulator. Make sure you have a big enough
heat sink on the regulator transistor and it is placed in a cool spot.
The up side to a linear regulator is less electrical noise on the power buss.
Also BTW most modern avionics use low cost linear regulators on the input that have
a capability of probably handling as much as 35 volts input with out blowing.
They also probably have a diode to prevent being hooked up to the battery
backwards. If not they should.
I am sure Tracy uses such low cost regulators in his EFI/IGN computer.
What is max input voltage Tracy?
Paul Lamar
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