, 27 March 2013, 22:59
Subject: Re: [time-nuts] OT - DC-10 gyros
I neglected to mention that. The DC resistance of the motor windings is roughly
200 ohms. I estimate the power draw is 2 watts. Haven't measured the
inductance.
I probably could just use some FETs and build a simple class-B amp
A good solution to generate 400 Hz (for European amateurs at least)
may be this: http://www.helmut-singer.de/stock/1814769336.html
Plus three amplifier stages, of course.
I am interested in gyros too. Have a sealed Whittaker displacement
gyro (marked as Western Electric GS-19719) and a Western
It's almost certainly part of the flight stability / autopilot system,
as suggested privately by another time-nut.
The gyros spin up nicely and run quietly, so sounds like the bearings
are fine.
I was using an old Yamaha amplifier I had around for the 400Hz drive. I
think I'm going to go the
:18
Subject: Re: [time-nuts] OT - DC-10 gyros
It's almost certainly part of the flight stability / autopilot system, as
suggested privately by another time-nut.
The gyros spin up nicely and run quietly, so sounds like the bearings are fine.
I was using an old Yamaha amplifier I had around
Subject: Re: [time-nuts] OT - DC-10 gyros
Hi Bill,
The amp I used was similar to this circuit
http://www.circuitstoday.com/100w-mosfet-power-amplifier which is a common
design. Supply is 45V (unregulated rectified and filtered 30V transformer) so
will drive 26V out OK.
I've also used modules from
Hi Bill,
Well, I can come up with something topical, read on. :)
[snip]
Topical in a more abstract way, strapdown systems really are very
interesting. They require precise integration of the rate output over
time to derive velocity and position, and really weren't practical until
the 70's
-nuts] OT - DC-10 gyros
Hi Bill,
Well, I can come up with something topical, read on. :)
[snip]
Topical in a more abstract way, strapdown systems really are very
interesting. They require precise integration of the rate
output over
time to derive velocity and position, and really
If I did not go the microcontroller PWM route I would use a Johnson
counter (twisted ring counter) to directly generate three 120 degree
phases. There is a good example here:
http://www.allaboutcircuits.com/vol_4/chpt_12/6.html
On Wed, 27 Mar 2013 21:55:32 -0400, Bob Camp li...@rtty.us 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
that was stripped for parts around 2000. The gyro included the pull tag
How about one of those 2kw car stereo amps with a 555 input tone ?
--- On Wed, 3/27/13, Bill Ezell w...@quackers.net wrote:
From: Bill Ezell w...@quackers.net
Subject: [time-nuts] OT - DC-10 gyros
To: time-nuts@febo.com
Date: Wednesday, March 27, 2013, 1:40 PM
Well, I can come up
...@quackers.net
Subject: [time-nuts] OT - DC-10 gyros
To: time-nuts@febo.com
Date: Wednesday, March 27, 2013, 1:40 PM
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
] OT - DC-10 gyros
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
that was stripped for parts around 2000. The gyro
For thumbsized gyros, the power-drain is probably very slight.
A class-D may or may not be a good idea, I'd worry about the
stability faced with a weird load like motors.
That said, I have been toturing one of these to no end, and
not managed to kill it yet:
Hi
The first question is how much 400 Hz power do I need?. Without knowing if
it's tens of amps (no, it's not…) or a tenth of an amp, it's a bit though to
decide how much to spend on the solution.
Eight ohms at 28 volts would be just a bit under 4 amps. It's also right at 100
watts. I'd be
: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@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
Hi
The first question is how much 400 Hz power do I need?. Without
I neglected to mention that. The DC resistance of the motor windings is
roughly 200 ohms. I estimate the power draw is 2 watts. Haven't
measured the inductance.
I probably could just use some FETs and build a simple class-B amp. The
sine wave doesn't have to be absolutely pure. Frequency
Yeah I'd join a gyro-nuts group. I have a shelf full of weird gyros, a stable
platform, other gyro stuff. I made a little power supply to make 28 volts 3
phase 400 Hz, found it in an app note, for running a set of three tiny rate
gyros I picked up. I'll go dig it out and let you know.
An appropriate (but small) Group already exists:
http://tech.groups.yahoo.com/group/Aerospace_Hardware_Collectors_Group/
-John
===
Yeah I'd join a gyro-nuts group. I have a shelf full of weird gyros, a
stable
platform, other gyro stuff. I made a little power supply to
Hi
For that kind of power, I'd dig out an audio transformer and drive it with
something like an LM-380.
Bob
On Mar 27, 2013, at 6:59 PM, Bill Ezell w...@quackers.net wrote:
I neglected to mention that. The DC resistance of the motor windings is
roughly 200 ohms. I estimate the power draw
The circuit I built used a ULN3751Z (TO-220) amplifier chip and some capacitors
to create the phase shifts for making 3 phase. Very simple oscillator circuit.
Haven't found the docs yet but found the unit itself.
On 3/27/2013 6:59 PM, Bill Ezell wrote:
I neglected to mention that. The DC
...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bill Ezell
Sent: Wednesday, March 27, 2013 3:40 PM
To: time-nuts@febo.com
Subject: [time-nuts] OT - DC-10 gyros
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
Bill Ezell;
Your Gyro may require 3 phase, 400 cps, 28 vac, Sine wave.
A simple Buffered Phase Shift Oscillator for 400 cps can create the Sine Wave.
https://www.circuitlab.com/circuit/h6v28g/buffered-phase-shift-oscillator/https://www.circuitlab.com/circuit/bakd83/phase-shift-oscillator-ii/You
Hi
If three phase is actually needed, I'd suggest something like a cheap PIC with
three PWM outputs. Fairly simple R/C's on the outputs should be plenty good
enough to filter out any crud. Good frequency stability / accurate phase shift
/ cheap. What's not to like ….
Bob
On Mar 27, 2013, at
I have a little dynamotor somewhere which makes 3 phase 400 Hz. Tiny little
thing! Only puts out like 15 VA, and not very noisy either. IIRC is was called
an Instrument inverter
On 3/27/2013 9:55 PM, Bob Camp wrote:
Hi
If three phase is actually needed, I'd suggest something like a cheap
On 3/27/13 3:20 PM, Bob Camp wrote:
Eight ohms at 28 volts would be just a bit under 4 amps. It's also
right at 100 watts. I'd be very surprised it you need anywhere near
that much current. You probably want a pure sine wave to keep
everything happy. A lot of the simple inverters are sort of
It was almost certainly for powering a WWII vintage fluxgate compass system.
-John
==
I have a little dynamotor somewhere which makes 3 phase 400 Hz. Tiny
little
thing! Only puts out like 15 VA, and not very noisy either. IIRC is was
called
an Instrument inverter
On
On Mar 27, 2013, at 22:54, Jim Lux jim...@earthlink.net wrote:
On 3/27/13 3:20 PM, Bob Camp wrote:
Of course, for the more mechanically inclined.. what about a big flywheel
driving an alternator. You might be able to rejigger a car alternator. I
don't recall how many poles they
If you need good 3 phase 400 Hz you can get a VFD which goes up that high and
program it to just sit there making 400 Hz.
On 3/27/2013 11:16 PM, bownes wrote:
On Mar 27, 2013, at 22:54, Jim Lux jim...@earthlink.net wrote:
On 3/27/13 3:20 PM, Bob Camp wrote:
Of course, for the more
Crikey - an alternator?
Automotive alternators typically have 6 poles, which delivers
60 Hz at 1200 RPM. You would need to go to 8000 RPM to get 400
Hz, or a bit more than 133 revs per second. That's really
humming along.
When I was younger, and found a tank gyro about 3 in diameter,
it needed
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