Yahoo Groups archive
Messages
Page 55 of 307 · 15341 messages matched
2009-05-16 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Brian" wrote: > > I know pressure is equal on all sides. Hmm. This depends what you mean by "sides". If you're counting the top and the bottom, then no. Imaging a cube instead of the ball and imagine that it is oriented with one face parallel to
2009-05-16 by dlc
Brian wrote: > I think I understand what you are saying. I know pressure is equal on all sides. So as the ball desends in the water the point of Bouyancy would raise from the center of the ball. Would this cause it to rise faster at deaper depths? If it were a balloon it'd be the
2009-05-16 by John Samperi
At 12:10 PM 16/05/2009, you wrote: >I think John is correct. It seems a case of "premature initialization". The cpu may start and finish before the oscillator has started to get warmed up...... Regards John Samperi ******************************************************** Ampertro
2009-05-16 by Phil Birkelbach
That is correct. A cubic foot of water weighs considerably more than 10 oz. You could take that thing to the bottom of the Gulf and let it go and it'll shoot straight back up. This does assume that it doesn't get crushed somewhere along the way. Pressure does not matter. The assu
2009-05-16 by Brian
I think John is correct. Also, the default setting per the datasheets is 1MHz and calibration is set (page 28 of the datasheet). When programed at 8MHz the calibration is not set and requires manual setting and a longer startup time. Page 29 talks about saving the value to eprom
2009-05-15 by Brian
I think I understand what you are saying. I know pressure is equal on all sides. So as the ball desends in the water the point of Bouyancy would raise from the center of the ball. Would this cause it to rise faster at deaper depths? Brian --- In AVR-Chat@yahoogroups.com, Phil Bir
2009-05-15 by Bob Paddock
> i want make project for measuring the level of water on the tank that > approximately 15 m high. what senssor that i should use ? http://www.analog.com/library/analogDialogue/archives/43-02/level_sensing.html The comments from that post point to real hardware: https://www.blogg
2009-05-15 by Brian
I might be wrong but what you are saying is if I have a non-compressable ball weighing 10 oz displacing 1 cubic foot of water it would take the same amount of force to hold it under 50 foot of water as it would at 100 feet? If weight and volume didnt change what would keep it fro
2009-05-15 by John Samperi
At 09:31 PM 15/05/2009, you wrote: >This suggests that the internal osc is running at 16MHz. You are a MIRACLE worker. :-) >(but Bod is not enabled, which the datasheet says it should be with >this setting). If I >change it to 6CK+64ms then it appears to start up correctly every
2009-05-15 by Ken Holt
No, the buoyancy of a submerged object does not increase with depth because water density does not increase with depth(not much anyway). The buoyancy is proportional to the differential pressure across the object. Jim Wagner wrote: > > > But water density increases with depth, an
2009-05-15 by Robert Tilden
The liquid in the modern version of Galileo's Thermoscope may not be water... As I understand it, in the original version the floats were open, inverted 'cups' in which the trapped air changed volume with temperature, causing the floats to rise or fall. The modern version uses se
2009-05-15 by Jim Wagner
This is exactly why the floaters in a Galilleo's Thermoscope hover at a specific depth. There is a density gradient in a column of fluid. At a greater depth, the floater is lighter than the fluid it displaces and at a lesser depth, it is heaver than the fluid it displaces. Defini
2009-05-15 by Tim Mitchell
Hi folks, Got a weird problem with a Mega8. It's in a timer device, the customer was reporting that the timed periods were half what they should be. On testing it, the timed periods were indeed half, unless you reset the device using the ISP header, in which case it worked correc
2009-05-15 by Brian
I was on Submarines in the Navy. They do compress but that is under a couple hundred feet of water. the compression of the plastic ball, could even be solid, should be small and still produce a measurable upforce with depth. Brian --- In AVR-Chat@yahoogroups.com, David VanHorn wr
2009-05-15 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Brian" wrote: > > From what I know, as the water > level rises the pressure at the > bottom increases causing more > of an uplift of an object held > at the bottom. OK, forget Archimedes, have a word with your tenth-grade physics teacher. Bouyanc
2009-05-15 by David VanHorn
On Thu, May 14, 2009 at 11:37 PM, dlc wrote: > Ahem, > > Water density is a constant, water _pressure_ increases with depth, > and if the ball acts the way my BC does, the air in the plastic ball > loses buoyancy as the water depth increases. But since my BC compresses > with dep
2009-05-15 by dlc
Ahem, Water density is a constant, water _pressure_ increases with depth, and if the ball acts the way my BC does, the air in the plastic ball loses buoyancy as the water depth increases. But since my BC compresses with depth and the plastic ball probably wouldn't, that might not
2009-05-15 by Roy E. Burrage
I've lost the original post about this application, but we've had to use level sensors here a good bit. Capacitive sensors will be very temperature sensitive. This is not just a function of capacitor plate physical issues, but the vapor in the vessel. Vapor in the vessel will als
2009-05-15 by Alex Shepherd
> Detection range is only 1.5m. OP asks for 15m. I was considering one of these: http://www.sparkfun.com/commerce/product_info.php?products_id=9009 For my water tanks but they are completely buried so could get flooded in a storm so I might try the: measuring the upwards force ex
2009-05-15 by Jim Wagner
But water density increases with depth, and thus apparent buoyancy increases as the water gets deeper. Jim Wagner Oregon Research Electronics On May 14, 2009, at 5:28 PM, Graham Davies wrote: > > > --- In AVR-Chat@yahoogroups.com, "Brian" wrote: > > > > ... a pressure sensor at t
2009-05-15 by Jim Wagner
Detection range is only 1.5m. OP asks for 15m. Jim Wagner Oregon Research Electronics On May 14, 2009, at 4:49 PM, Brian wrote: > > > Jameco has this > > http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=129120& > > y
2009-05-14 by Brian
There is a user manual at: http://www.jameco.com/Jameco/Products/ProdDS/129120MAN.pdf It also has a schmatic to help interface it. Brian --- In AVR-Chat@yahoogroups.com, "Alex Shepherd" wrote: > > > Detection range is only 1.5m. OP asks for 15m. > > I was considering one of these
2009-05-14 by Brian
From what I know, as the water level rises the pressure at the bottom increases causing more of an uplift of an object held at the bottom. Brian > > Are you suggesting that the force of buoyancy on the plastic ball will increase as the water level increases? You might want to hav
2009-05-14 by wagnerj@proaxis.com
This might work for small depth changes, such as trying to hold a water level constant. But, I would not bet anything on having it work over a 15 meter range. Jim Wagner Oregon Research Electronics > How about this? > A water tight ball with a magnet in it. A magnetic field senso
2009-05-14 by Brian
This is true if you use the device as is but.... using only the sensor module, not using the control board, and a micro you should be able to extend the range. Thinking this is an AVR group it may be dooable. As for me I would have to modify it. Couldnt resist, the only thing I w
2009-05-14 by Dennis Clark
How about this? A water tight ball with a magnet in it. A magnetic field sensor at the top of the tank. The higher the fluid level, the more mag field sensed. Use a permeable tube to hold the floating ball so that it stays more-or-less in one area. A magnetic sensor sensitive eno
2009-05-14 by Graham Davies
--- In AVR-Chat@yahoogroups.com, "Brian" wrote: > > ... a pressure sensor at the top > of the tank and a rod extending > down into the tank with a plastic > ball fixed at the end. the higher > the water level the more force on > the sensor. Are you suggesting that the force of bu
2009-05-14 by Brian
Jameco has this http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=129120& you could interface it with a microcontroller and obtain almost any distance within reason. Brian --- In AVR-Chat@yahoogroups.com, wagnerj@...
2009-05-14 by Brian
I think I may have an idea. a pressure sensor at the top of the tank and a rod extending down into the tank with a plastic ball fixed at the end. the higher the water level the more force on the sensor. Brian --- In AVR-Chat@yahoogroups.com, Muhammad Amiruddin wrote: > > Dear all
2009-05-14 by Muhammad Amiruddin
If we use a pressure sensor, first idea on my head is a load cell, but i have experience with a load cell, it need a diff amp , little movement of the load cause so many noise and ripple on diff amp output, how to minimize that ? --- On Wed, 5/13/09, Bruce Parham wrote: From: Bru
2009-05-14 by Jim Wagner
Campbell Scientific makes a "bubbler" to measure water depth. They get a good price for it, also. Jim Wagner Oregon Research Electronics On May 13, 2009, at 6:41 PM, Robert Tilden wrote: > > > Besides the ultrasonic sensor there are a number of other methods.. > > A donut shaped
2009-05-14 by Julian Higginson
I've been looking at VEGA stuff lately for liquid level detection purposes. http://www.vega.com/au/Level_measurement_ultrasonic_VEGASON63.htm this does what you want.... just.... It is a loop powered 4-20mA acoustic probe, and so you just sit it above the water, and then give it
2009-05-14 by Robert Tilden
Besides the ultrasonic sensor there are a number of other methods... A donut shaped float incorporating a magnet which rides up and down around a magnetostrictive line. One sends a pulse down the line and measures the return from the magnetic float location. Very accurate. A donu
2009-05-13 by kernels_nz
Back when I was at Uni a few years ago, one of the students had a project to electronically measure the water level in a plastic tank. Best way I have seen this done is run two parallel metal plates along the depth of the tank and then look at the change in capacitance between th
2009-05-13 by John Samperi
At 06:04 AM 14/05/2009, you wrote: >it's cheap and easy to repair. From the amount of traffic generated by this thread it is clear that the world DOES NEED a good, reliable, easy to use water/liquid sensor!! I went through this a couple of years ago when I got my rain water tank
2009-05-13 by Jeffrey Engel
If a little noise can be tolerated in the sensor input, you can add air to the tube. As the bubbles leave the end of the tube, they'll bounce the pressure a little. Some of the advantages are that you can put the gauge at the top of the tank, it's cheap and easy to repair. If you
2009-05-13 by Ken Holt
My water pressure sensor has only failed due to freezing of the water. My house fresh water tank is only 4' tall, and not quite cylindrical, so the pressure reading is not quite linear with volume. I use a DVM always-on to read millivolts: 100mv empty, 500 mv full. The major prob
2009-05-13 by David VanHorn
> All to avoid purchase of a sensor which won't be damaged by the liquid? > > The compressed air in the inverted standpipe will eventually dissolve > into the liquid. This proposed solution will not work in a static > situation, must be cyclical allowing the air in the standpipe
2009-05-13 by David Kelly
On Wed, May 13, 2009 at 09:47:39AM -0700, Bruce Parham wrote: > Sorry, my earlier response was incomplete, just the germ of an idea. > > Since the inverted standpipe is initially filled with air, when the > liquid level rises, the gas will be compressed allowing liquid to > enter
2009-05-13 by David VanHorn
If you need to keep the liquid out, you can use a diaphram. The diaphram flexes and passes the pressure change, but you could fill the backside with dry nitrogen. -- There is no computer problem which cannot be solved by proper application of a sufficiently large hammer.
2009-05-13 by Bruce Parham
Sorry, my earlier response was incomplete, just the germ of an idea. Since the inverted standpipe is initially filled with air, when the liquid level rises, the gas will be compressed allowing liquid to enter the tube which will reduce the pressure head. The actual pressure measu
2009-05-13 by Philippe Habib
I worked on a lab device that used this system and water droplets still found their way into the sensor and toasted it. The solution was an expensive custom gauge protector. So if you use this approach, you need to be sure the mechanical stuff is 100% taken care of properly. On M
2009-05-13 by David VanHorn
> At the very least study the maximum pressure the sensor can be exposed > in addition to its full scale range. A very good idea.. Water does not compress, but your sensor does. "what was that crunching sound?" -- There is no computer problem which cannot be solved by proper appl
2009-05-13 by David Kelly
On Wed, May 13, 2009 at 08:09:32AM -0700, Bruce Parham wrote: > > Given that water pressure = 1.363 PSI/m, a 15 m water head will > produce 1.363 PSI/m x 15 m = 20.45 PSI. A 25 to 30 PSI full scale > sensor should do the trick. I haven't fielded water pressure sensors but I'd ser
2009-05-13 by Bruce Parham
I like the method used in most washing machines where they place a pressure sensor above the liquid and run an open ended tube down to the bottom. That keeps the sensor and electronics dry. Given that water pressure = 1.363 PSI/m, a 15 m water head will produce 1.363 PSI/m x 15 m
2009-05-13 by Muhammad Amiruddin
thanks for all you --- On Mon, 5/11/09, Muhammad Amiruddin wrote: From: Muhammad Amiruddin Subject: Re: [AVR-Chat] (unknown) To: AVR-Chat@yahoogroups.com Date: Monday, May 11, 2009, 3:10 AM Is there any other sensor that can measure range over than 15 m? --- On Mon, 5/11/09, Jim
2009-05-13 by Philippe Habib
I have seen ultrasonic sensors that do what you want if you can't add a pressure sensor at the bottom. On May 12, 2009, at 7:09 PM, Brian wrote: > I think the best non-movement sensor would be a presure sensor at > the bottom of the tank. No moving parts and it can be sealed. So
2009-05-13 by Brian
I think the best non-movement sensor would be a presure sensor at the bottom of the tank. No moving parts and it can be sealed. So it could measure many liquids. Brian --- In AVR-Chat@yahoogroups.com, Muhammad Amiruddin wrote: > > Dear all, > > please help me, > > i want make pro
2009-05-11 by Robert Tilden
http://www.apgsensors.com/ultrasonic-sensor/dcu-1100.html ----------------------------------- Bob Tilden, tilden@northwestern.edu High Energy Physics Group Northwestern University -----Original Message----- From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behal
2009-05-11 by Robert Adsett
Muhammad Amiruddin wrote: > Is there any other sensor that can measure range over than 15 m? Float Pressure/Weight Radar Conduction Optical should be possible too Robert -- http://www.aeolusdevelopment.com/ From the Divided by a Common Language File (Edited to protect the guilty)