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Oct 08, 2009, 11:16 PM
Registered User
I was able to get one spinning by using a 555 timer circuit and a mosfet driver. One had a noisy bearing, the other was much quieter. I have not been able to figure out how to read the output yet.

Reed



Quote:
Originally Posted by saff678
jglenn, are you saying you think there's another pin with a sinusoid output to compare to one of these inputs? Or do you think maybe it's just compare the aux sinusoid to the main.

Has anyone successfully powered the gyro and/or picked off the output data in any way? I was trying to power mine today, just playing with voltages and pins; the closest I got was a little click and spark when I connected blue/yellow to +15V/-15V. I don't know whether that's correct operation, or whether it's off the right voltage or what.
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Oct 08, 2009, 11:30 PM
Quote:
Originally Posted by reedchristiansen
I was able to get one spinning by using a 555 timer circuit and a mosfet driver. One had a noisy bearing, the other was much quieter. I have not been able to figure out how to read the output yet.

Reed
Reed,
Any chance we could get a bit more info on what worked? What pins were you going to, and at what voltage?
Oct 09, 2009, 06:20 AM
Registered User
There has to be at least 2 coils in an LVDT. One might be center tapped.

I would think that 2 of the wires from the gyro are for the motor, which
would be a brushed dc motor, probably. Might be ac though. This is a mystery.

Have to examine the gyro specs carefully. Try this chip!

http://www.analog.com/en/sensors/lvd...s/product.html

THEORY:

http://www.rdpe.com/displacement/lvd...principles.htm
Oct 09, 2009, 09:20 AM
Registered User
Quote:
Originally Posted by saff678
Reed,
Any chance we could get a bit more info on what worked? What pins were you going to, and at what voltage?

We used a 15 lm7815 voltage regulator and a single sided power supply through a 555 timer and 3 half bridges. The black wire is ground and +/- 15 volt square wave at 600 (down to 400 and up to 700 hz worked - RPM changed) to the green wire. Like the example diagram showed, we ran the +/-15 volts through a cap and into the red wire also - not sure what that does - It does not seem to need to be hooked up.

I can give you more details on the schematic when the guy who did it comes in.

The output cannot be easily read on an oscope. I suspect that the other posters are right and that it is an LVDT, and we need an LVDT driver chip.

Reed
Oct 09, 2009, 01:26 PM
Registered User
Jack Crossfire's Avatar
Is Procerus selling old school UAV's now? Throw in some vacuum tubes & custom chrome & U might get a TV show.
Oct 09, 2009, 02:42 PM
Alam
Quote:
Originally Posted by reedchristiansen
We used a 15 lm7815 voltage regulator and a single sided power supply through a 555 timer and 3 half bridges. The black wire is ground and +/- 15 volt square wave at 600 (down to 400 and up to 700 hz worked - RPM changed) to the green wire. Like the example diagram showed, we ran the +/-15 volts through a cap and into the red wire also - not sure what that does - It does not seem to need to be hooked up.

I can give you more details on the schematic when the guy who did it comes in.

The output cannot be easily read on an oscope. I suspect that the other posters are right and that it is an LVDT, and we need an LVDT driver chip.

Reed
It will be good if you can post a hand write diagram, how to connect different wires to at-least run the gyro motor, LVDT portion can be solve later on. I am also ordering few gyros.

Thanks.
Fakhre Alam
Oct 09, 2009, 06:18 PM
Registered User
Those things are just artifacts of ancient history. Today we have GWS
$38 gyro's made for planes that work fine (RX-PG-03) useful for stabilizing
any axis. I am using one for pitch on a plane that drops the nose in turns.
Works ok unless you get wild with it.
Oct 10, 2009, 05:58 PM
Alam
Quote:
Originally Posted by jglenn
Those things are just artifacts of ancient history. Today we have GWS
$38 gyro's made for planes that work fine (RX-PG-03) useful for stabilizing
any axis. I am using one for pitch on a plane that drops the nose in turns.
Works ok unless you get wild with it.
This can not do the job because it not holding the angle in which you were before the gyro kicks-in, like not maintaining the roll or pitch angle (to keep the plane level), just giving up or down servo movement.

Fakhre Alam
Oct 10, 2009, 06:53 PM
Registered User
It works well enough for what I need. The gyro is always engaged. I generally fly gentle turns to keep within the field. This particular plane for some reason drops the nose on almost any turn. Not using a mixing radio, and wanted to try a gyro anyway. As long as you limit the bank angle, it will stabilize the pitch.

You can put a gyro on any single axis. Some scale fliers use them on rudder to
make the take-off run easier, old WW1 birds can be touchy.

They will also stabilize against wind gusts to a certain extent. I'm not saying a
full IMU autopilot would not do a better job, still saving up for one.
Oct 13, 2009, 11:13 PM
Registered User

Rate Output


Through some clever work by my brother, we got a rate output from the gyros on the O-scope.

For driving the motor we used the exact circuit provided with the gyro.

For driving the LVDT we used a 555 timer producing a square wave at 5khz. The output is standard LVDT. Rate is amplitude (very sensitive - just looking at the scope, appears quite a bit more sensitive then the ADXRS.)

Direction is the phase relative to the the driving wave into the LVDT.


I can give wire colors when I get into work tommorow.

Reed

Quote:
Originally Posted by FAKHREALAM
It will be good if you can post a hand write diagram, how to connect different wires to at-least run the gyro motor, LVDT portion can be solve later on. I am also ordering few gyros.

Thanks.
Fakhre Alam
Oct 13, 2009, 11:16 PM
Registered User
Quote:
Originally Posted by Jack Crossfire
Is Procerus selling old school UAV's now? Throw in some vacuum tubes & custom chrome & U might get a TV show.

- Time will tell, whatever it takes to make a buck !


Who knows, these gyros could turn out to make a nice reference TRIAD for IMU work - or they could be noisy waists of time.

Reed
Oct 14, 2009, 09:48 AM
Registered User

wiring


Here is how to wire the gyro to read the output as a sign wave on a scope.

Powering the motor:
Use the red, green, and black wires as shown in the schematic that is provided with the gyros. This requires a +/- 15 volt brick type power supply.


Reading the signal:
1. Create a 5khz square wave using a 555 timer. Feed the output of the 555 through a .1 uf cap into the yellow wire. The ground of the 555 is the black wire (motor power ground as well).
555 pinout:
1. ground
2. pin 6 AND .01 uf to ground
3. 100 ohm to .1 uf to yellow wire (this is the output)
4. +15
5. .1 uf to ground (I need to double check this value)
6. 50k ohm to pin 7 AND pin 2
7. 50k ohm to pin6 (same as above) AND 1k ohm to ground
8. +15

2. hook scope ground to blue wire
3. hook ch1 of scope probe to yellow wire. Trigger on this signal.
4. hook channel 2 to white wire and zoom way in. This is your signal. There is some high frequency content - probably from feeding the lvdt with a square wave instead of a sign wave, but the rate output is obvious.


Reed








Quote:
Originally Posted by reedchristiansen
Through some clever work by my brother, we got a rate output from the gyros on the O-scope.

For driving the motor we used the exact circuit provided with the gyro.

For driving the LVDT we used a 555 timer producing a square wave at 5khz. The output is standard LVDT. Rate is amplitude (very sensitive - just looking at the scope, appears quite a bit more sensitive then the ADXRS.)

Direction is the phase relative to the the driving wave into the LVDT.


I can give wire colors when I get into work tommorow.

Reed
Oct 18, 2009, 04:28 PM
Alam
Quote:
Originally Posted by reedchristiansen
Here is how to wire the gyro to read the output as a sign wave on a scope.

Powering the motor:
Use the red, green, and black wires as shown in the schematic that is provided with the gyros. This requires a +/- 15 volt brick type power supply.

Reed
Good job. Please let me know why we need another 5KHZ generator, LVDT need to give the same output with only difference in phase with respect to motor driving square wave generated by LM741(we probably need to amplify the LVDT signal, if u post LM555 hand written diagram will help). Please post the diagram and snap the scope one too, will help.

Fakhre Alam
Oct 21, 2009, 09:52 AM
Quote:
Originally Posted by reedchristiansen
Here is how to wire the gyro to read the output as a sign wave on a scope.

Powering the motor:
Use the red, green, and black wires as shown in the schematic that is provided with the gyros. This requires a +/- 15 volt brick type power supply.


Reading the signal:
1. Create a 5khz square wave using a 555 timer. Feed the output of the 555 through a .1 uf cap into the yellow wire. The ground of the 555 is the black wire (motor power ground as well).
555 pinout:
1. ground
2. pin 6 AND .01 uf to ground
3. 100 ohm to .1 uf to yellow wire (this is the output)
4. +15
5. .1 uf to ground (I need to double check this value)
6. 50k ohm to pin 7 AND pin 2
7. 50k ohm to pin6 (same as above) AND 1k ohm to ground
8. +15

2. hook scope ground to blue wire
3. hook ch1 of scope probe to yellow wire. Trigger on this signal.
4. hook channel 2 to white wire and zoom way in. This is your signal. There is some high frequency content - probably from feeding the lvdt with a square wave instead of a sign wave, but the rate output is obvious.


Reed
Hi Reed,

Thanks for the excellent description. I was wondering, seeing as I'm having problems on the motor power circuit - was there any physical indication that the motor was powered and turning? I don't want to be sending any power to this thing while it isn't moving by mistake, as I imagine that it would cause damage. Thanks.
Oct 21, 2009, 09:04 PM
Alam

Gg440a18 Missile Rate Gyro Info Goldmine G17270


Quote:
Originally Posted by saff678
Reed,
Any chance we could get a bit more info on what worked? What pins were you going to, and at what voltage?
Here is the diagram and info of the G440A18 Missile Rate Gyro (Goldmine part# G17270).

I received my gyros today, just trying to figure out the output, u will get good new by coming Monday.

Fakhre Alam


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