N
Nikola
Guest
Hello i'm making my own vario meter for sensing vertical speed can you
give me some link to sensors for that type of device??
Nikola.
give me some link to sensors for that type of device??
Nikola.
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R
Roger Hamlett
Guest
"Nikola" <nikolahg@yahoo.com> wrote in message
news:3F5B7038.B63F9A0A@yahoo.com...
You will have to decide on the 'methodology' that you want to use for the
variometer. So (for instance), you could use the traditional approach, of
having a gas bottle with a slow 'leak' to the external atmosphere. Then have
a two port (pressure difference) sensor with high resolution, but limited
range, connected between the bottle, and the external atmosphere. This has
the advantage of very high potential resolution, but the extra complexity of
the bottle and vent (though standard versions of these are readily
available). The alternative, is to have a single port sensor (these have a
sealed internal cavity, and return the pressure _relative_ to the pressure
in the fixed cavity). You then take the readings from this, and generate the
rate of change of these readings, as the vario data, effectively performing
the same operation as the gas bottle in software. The limiting factor here
becomes the resolution of basic sensor. The 'gas bottle' approach is used in
the standard mechanical vario systems, and can easily give resolutions in
the order of 0.1mB/minute (in 'glider' units).
There are then questions about power consumption. The pressure sensors tend
to require a reasonable (though not silly) amount of power. Hence in battery
operated equipment (the 'altimeter' watches for instance), the sensor is
only turned on for a brief moment to read the pressure, and then switched
off when not required.
So the best sensor choice, will depend on the methodology you choose, and
the sort of sensitivity required. Typical choices would be:
http://e-www.motorola.com/webapp/sps/site/taxonomy.jsp?nodeId=03QvzRmxrqScNb9036
These are the Motorola sensor family, commonly used in many simple
instruments of this sort.
Honeywell do a similar range.
Lucas do their 'NovaSensor', which has better basic linearity than the above
devices at:
http://www.novasensor.com/catalog/catalog.html
Then there are the 'vibrating' sensors, that give yet higher accuracy, like
those from Pressure systems at:
http://www.psih.com/quartzonix.html
These have the advantage of having a frequency output, which removes the
need for an AD converter, reducing the cost of other parts involved.
There are also other designs, that can be used, but on a price/performance
basis, these are currently the 'best'.
If this is a 'one off', and you are not wanting to get involved in
purchasing a lot of parts, and don't need massive accuracy, you might also
look at some of the units being offered for amateur rocketry. One of the
designs readily available from suppliers, is a small transducer, built and
working, that returns altitude as a serial data stream for use with the
'logging' systems, and parachute trigger systems, being used on the larger
models.
Best Wishes
news:3F5B7038.B63F9A0A@yahoo.com...
shift.Hello i'm making my own vario meter for sensing vertical speed can you
give me some link to sensors for that type of device??
Any of the piezo pressure sensors, either piezo resistive, or frequency
You will have to decide on the 'methodology' that you want to use for the
variometer. So (for instance), you could use the traditional approach, of
having a gas bottle with a slow 'leak' to the external atmosphere. Then have
a two port (pressure difference) sensor with high resolution, but limited
range, connected between the bottle, and the external atmosphere. This has
the advantage of very high potential resolution, but the extra complexity of
the bottle and vent (though standard versions of these are readily
available). The alternative, is to have a single port sensor (these have a
sealed internal cavity, and return the pressure _relative_ to the pressure
in the fixed cavity). You then take the readings from this, and generate the
rate of change of these readings, as the vario data, effectively performing
the same operation as the gas bottle in software. The limiting factor here
becomes the resolution of basic sensor. The 'gas bottle' approach is used in
the standard mechanical vario systems, and can easily give resolutions in
the order of 0.1mB/minute (in 'glider' units).
There are then questions about power consumption. The pressure sensors tend
to require a reasonable (though not silly) amount of power. Hence in battery
operated equipment (the 'altimeter' watches for instance), the sensor is
only turned on for a brief moment to read the pressure, and then switched
off when not required.
So the best sensor choice, will depend on the methodology you choose, and
the sort of sensitivity required. Typical choices would be:
http://e-www.motorola.com/webapp/sps/site/taxonomy.jsp?nodeId=03QvzRmxrqScNb9036
These are the Motorola sensor family, commonly used in many simple
instruments of this sort.
Honeywell do a similar range.
Lucas do their 'NovaSensor', which has better basic linearity than the above
devices at:
http://www.novasensor.com/catalog/catalog.html
Then there are the 'vibrating' sensors, that give yet higher accuracy, like
those from Pressure systems at:
http://www.psih.com/quartzonix.html
These have the advantage of having a frequency output, which removes the
need for an AD converter, reducing the cost of other parts involved.
There are also other designs, that can be used, but on a price/performance
basis, these are currently the 'best'.
If this is a 'one off', and you are not wanting to get involved in
purchasing a lot of parts, and don't need massive accuracy, you might also
look at some of the units being offered for amateur rocketry. One of the
designs readily available from suppliers, is a small transducer, built and
working, that returns altitude as a serial data stream for use with the
'logging' systems, and parachute trigger systems, being used on the larger
models.
Best Wishes
N
Nikola
Guest
Roger Hamlett wrote:
Thanks."Nikola" <nikolahg@yahoo.com> wrote in message
news:3F5B7038.B63F9A0A@yahoo.com...
Hello i'm making my own vario meter for sensing vertical speed can you
give me some link to sensors for that type of device??
Any of the piezo pressure sensors, either piezo resistive, or frequency
shift.
You will have to decide on the 'methodology' that you want to use for the
variometer. So (for instance), you could use the traditional approach, of......
Best Wishes