Show Posts
Pages: 1 2 3 [4] 5 6 ... 24
46  International / Proyectos / Re: Proyecto luz pulsada -dudas- on: May 03, 2014, 05:10:05 pm
Puedes estudiar los temas "voltaje rms" y "modulacion de ancho de pulso" para que comprendas mejor.
Este video quizas te ayude a observar lo que sucede y como varian la senal y el voltaje medido, al variar el ciclo util con modulacion de ancho de pulso. Es importante que notes, que el voltaje pico de la senal (en tu caso 5V, en el video 10V) no varia al cambiar el ciclo util (excepto cuando es 0% el ciclo util y no hay pulsos, por supuesto)
https://www.youtube.com/watch?v=271qPIFaC2E
47  Topics / Science and Measurement / Re: Volume Meassurement (Dry Method) on: May 02, 2014, 07:16:40 pm
I've been thinking on the 2 containers method you suggested and seems very feasible too; but perhaps, I will have the same 2 problems again: containers leak and temp dependency of the amount of air entering the first container (the one with the object) and it will basically be the same thing; but I really don't know either??. So far, the results I've obtained with one container, apparently indicate the method is working; but I still have to solve these two problems, that I think  are the reasons for (greater) inaccuracies, which only appear, once I open the container or the temp changes substantially. The results repeat, when temp is about the same and leaks are about the same, which I can observe by repeating the test over and over without opening the container.
Thanks.
48  International / Proyectos / Re: Medicion de Volumen (Metodo Seco) on: May 02, 2014, 04:44:13 pm
El "cacharro", lo tengo hecho; pero no creo que sea lo importante. Es solo un prototipo para probar el concepto.
Si observas el diagrama es basicamente eso con un Arduino controlando el sistema y la computadora comandandolo todo y visualizando los resultados en la pantalla. Aun estoy trabajando en este Proyecto.
49  Topics / Science and Measurement / Re: Volume Meassurement (Dry Method) on: May 02, 2014, 03:46:39 pm
Yes, making the container leak free has been really difficult. The main problem is the leaks change every time it is opened to place the sample inside. However, once the container is sealed and the test repeated, it looks the repeatability of the results is good (if temp does not changes significantly). I already checked a local machine shop with a proposed container to be built; but since my goal for now is to find if the method could be used, I have been delaying that.
The fixed amount of air looks a good assertion; but I'm using the air pressure drop in the vessel as an indirect method of finding the volume. The initial pressure from which deflation occurs is measured on every test. The time it takes to reach 36.7% of the initial value is recorded and the volume calculated. I have changed the initial pressure at which the container is filled and the time to reach 36.7% of the new initial Pr. appears to be about the same.
Another problem affecting the results is temp drift. The air volume required to reach the required initial Pr changes at different temps, and that affects the calculated volume. This is possible to solve (I think) and I have been trying to find the relationship between the measured volume and temp, (by also measuring the temp); but that has proven to be really difficult.
I don't know much about fluids dynamics either; but I wanted to test if this method could work.
I'm still working on this.


50  Topics / Science and Measurement / Re: Something like an ARDULAB, please! on: May 01, 2014, 06:48:05 am
This posts may help you:
http://forum.arduino.cc/index.php?topic=226510.0
http://forum.arduino.cc//index.php?topic=188610.msg1396951#msg1396951


51  Topics / Science and Measurement / Re: Functions Generator on: April 30, 2014, 11:33:52 am
Thank you. While under pressure  people tend to make mistakes. At the end of the day, I think its still good to share these Projects here, even without code, as we all benefit with ideas. I have also posted some codes here before.
52  Topics / Science and Measurement / Re: Functions Generator on: April 30, 2014, 09:34:43 am
The truth of the matter is that these are codes I'm building for fun and they are probably full of inefficiencies, making them unsuitable for sale or anything like that.
53  International / Proyectos / Re: Medicion de Volumen (Metodo Seco) on: April 30, 2014, 08:08:47 am
Todavia tengo que trabajar mas en este Proyecto.
54  Topics / Science and Measurement / Re: Volume Meassurement (Dry Method) on: April 30, 2014, 08:05:41 am
I still have to work more on this Project, sorry.
55  Topics / Science and Measurement / Re: Create Your own Arduino Oscilloscope on: April 28, 2014, 08:08:04 am
Quote
i don't see any link smiley
Starting at 00:14.
56  International / Proyectos / Re: Ayuda para proyecto con Solenoides. on: April 25, 2014, 11:45:25 am
Quote
Si dispones de fuentes de alimentacion de PC en teoria puedes conectar varias en paralelo para conseguir la intensidad necesaria.
En teoria es possible; pero en la practica no es una buena solucion. Si las salidas son reguladas y los voltajes ligeramente diferentes se producen corrientes parasitas para igualar los voltajes al conectarse en paralelo.

Si no necesitas que todas las solenoids se activen simultaneamente entonces los requerimientos de la fuente en cuanto a corriente son mucho menores y siguiendo el ejemplo anterior puedes calcularla. En ese caso solo una solenoid a la vez) dada la abundancia de este tipo de Fuentes, puedes utilizer una ATX de computadora que de 1A de salida en los 12V.

57  International / Proyectos / Re: Ayuda para proyecto con Solenoides. on: April 23, 2014, 10:21:05 pm
Las 10 solenoides pueden ser activadas a la vez en alguna circunstancia? Te pregunto porque tengo entendido que no es muy facil conseguir una fuente de 12V 5A. Si ese es el caso, entonces la fuente debe ser capaz de entregar al menos un 20% mas de corriente que la maxima posible que demandara la carga para evitar que se sobrecaliente. En tu caso, entonces seria 6A y no 5A. Eso es sino anades algo mas como carga a los 12V. Eso hace que la fuente sea de 12V*6A=75 watts al menos. Pienso que no es muy facil  encontrar una fuente asi. No recuerdo bien; pero no creo que las Fuentes ATX de computadoras sean capaces de entregar tanta corriente en la salida de 12V. Si no es como pienso, entonces son muy buena opcion para tu proyecto, pues tanbiem entergan los 5V que necesitas.
58  Topics / Science and Measurement / Re: Volume Meassurement (Dry Method) on: April 23, 2014, 10:14:24 am
I started this Project because while working on the one below, I thought it was a good way to find out how many Gauges the operator had placed in the bench for real. This was perfect, as there was no need to add any extra hardware and only coding could solve the problem using the already installed hardware. I was seriously defeated at that time given the complexity of the whole thing, despite trying really hard for about a month and decided to tackle the problem in complete isolation from any other Project to better understand and study what was really going on.
I'm planning on posting a video with the rest of this project some day.

https://www.youtube.com/watch?v=HoorVivjawE
59  Topics / Science and Measurement / Re: Volume Meassurement (Dry Method) on: April 23, 2014, 10:04:36 am
Quote
this could explain the spike (air is hot at the end of inflation in the bottle) and when you stop it is cooling and the pressure decrease ...
the slight difference between the deflation too (strong deflation at the begining causing a drop of the temperature ...)

Interesting explanation and very possible. Thanks

Quote
Have you thought about differential methods or using acoustic resonance to probe
volume (the elastic constant of a container of gas depends on the volume of gas).

Thanks for the interesting links.
In practice, there are many different methods to solve the same problem. I had the intention to test this one, which by the way, I haven't found in use or tested anywhere else. Another alternative I think. Like any other, probably with some advantages as well as disadvantages.
60  Topics / Science and Measurement / Re: Functions Generator on: April 23, 2014, 08:40:48 am
Sorry, no its is not open source.
Pages: 1 2 3 [4] 5 6 ... 24