[time-nuts] OT - DC-10 gyros
tholmes at woh.rr.com
Wed Mar 27 18:35:05 EDT 2013
Good points, Bob. At 400 Hz and low power, I'd think a decent LC low-pass
filter would be feasible for cleaning up any trash on the inverter output.
LC to minimize the series losses and provide a bit of peaking at 400 Hz.
Tom Holmes, N8ZM
Tipp City, OH
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bob Camp
> Sent: Wednesday, March 27, 2013 6:21 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] OT - DC-10 gyros
> The first question is "how much 400 Hz power do I need?". Without knowing
> tens of amps (no, it's not.) or a tenth of an amp, it's a bit though to
> much to spend on the solution.
> Eight ohms at 28 volts would be just a bit under 4 amps. It's also right
> watts. I'd be very surprised it you need anywhere near that much current.
> probably want a pure sine wave to keep everything happy. A lot of the
> inverters are "sort of" sine waves. I think I'd vote for something like an
> audio amp driven by a nice clean / stable 400 Hz tone.
> On Mar 27, 2013, at 4:40 PM, Bill Ezell <wje at quackers.net> wrote:
> > Well, I can come up with something topical, read on. :)
> > I saw a 'Bendix yaw-rate gyro' on FleaBay recently for $14.50. Of
course, I had
> to buy it.
> > What I got was the yaw-rate gyro package from a Northwest Airlines DC-10
> was stripped for parts around 2000. The gyro included the pull tag with
> number, the license number of the A&P mechanic that pulled it, and some
> cool stuff.
> > What it turned out to really be is two gyros with two sets of
electronics in one
> box about 6" x 2" x 5" box, all vintage '80s or so. Even better, it's a
> system. The actual gyro wheel is about the size of your thumbnail. I've
> tracing things out, and I've gotten the gyros to spin up. I really love
> gyros for some reason, too bad there's not a gyro-nuts group. I'm going to
> great fun getting the package traced out and running.
> > So, to be a bit more topical, the package of course needs 28V 400Hz for
> gyros, 28VDC for something, and +/-15V for most of the electronics.
> > Question - anyone figured out some clever solution for the 400Hz power?
> faked it with a signal generator and power amp, but that's a bit bulky.
> I'll use one of the class-D amp ICs and a simple op-amp phase-shift sine
> > Topical in a more abstract way, strapdown systems really are very
> They require precise integration of the rate output over time to derive
> position, and really weren't practical until the 70's when small enough
> existed to do the requisite calculations. (I worked on the nav system for
> Trident missile back in my Draper Labs days).
> > --
> > Bill Ezell
> > ----
> > They said 'Windows or better'
> > so I used Linux.
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