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 wrote:
>Hi
>
>If thre
t
> Subject: Re: [time-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 t
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 7
I've not tried it and am not endorsing it but it looks a good low cost starting
point.
Robert G8RPI.
From: Robert Atkinson
To: Discussion of precise time and frequency measurement
Sent: Thursday, 28 March 2013, 12:20
Subject: Re: [time-nuts] OT - DC-10
t: 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 for the 400H
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 a
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
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. T
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 1
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 wrote:
On 3/27/13 3:20 PM, Bob Camp wrote:
Of course, for the more mechanically inclined.. wha
On Mar 27, 2013, at 22:54, Jim Lux 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 have..
A motor dri
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 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" s
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 chea
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 9
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
...@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
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 res
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 wrote:
> I neglected to mention that. The DC resistance of the motor windings is
> roughly 200 ohms. I estimate the power draw is < 2 watts. Ha
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 t
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.
Peter
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 sta
-
> From: 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
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
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:
http://classdaudio.com/ampli
Great to know there's someone around who loves complex electro-mechanical
systems! I thought the population had dropped to zero!
Regards,
Lee
- Original Message -
From: "Bill Ezell"
To:
Sent: Wednesday, March 27, 2013 2:40 PM
Subject: [time-nuts] OT - DC-10 gyros
l Ezell
> 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
How about one of those 2kw car stereo amps with a 555 input tone ?
--- On Wed, 3/27/13, Bill Ezell wrote:
From: Bill Ezell
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
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
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