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Topic: An air pump, that I can control the rate of the air being pumped? (Read 8212 times) previous topic - next topic

mcozire

Hi there, I am looking to push small round LEDs around a plastic tube, I thought I might achieve this by blowing them around essentially, using an air pump.

I was wondering does anyone know of an air pump, that I could control,

on/off air,
and
the rate or pressure of air, so that I can control the rate of which the items are being blown around the plastic tubing.

Many many thanks!

Mark.

Robin2

Are you expecting the LEDs to be lighting?  How will you get power to them?

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

Peter_n

Search Ebay for this: air pump 12v -car
It all depends on how much pressure and how much air flow you want. You could buy about ten different pumps and see which one is best for you.

MarkT

Such pumps are usually very loud indeed, being diaphragm pumps, since
fans stall at very small back pressures.

The speed of a diaphragm pump will control pressure and flow rate, but
I suspect the noise issue will mean having to contain the pump in an acoustically
padded box.

I also fear you'll find all the LED modules clump together due to small differences
in friction, unless you have a mechanical means to space them out.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

michinyon

You might want to consider a fixed speed pump which pumps air into a reservoir,    and then using a controllable valve to release air from the reservoir as much as you want it.

That is the way that the majority of air-powered devices work,   and they probably have a good reason for doing it that way.

raschemmel

Closed-loop air pump control is certainly do-able but not necessarily cheap. If  you want to control the pressure you need to be able to measure it. None of the commercially available 12V powered air pumps offer uC output so that means you need to combine open loop off the shelf with mosfet switching of the air-pump based on air pressure sensor feedback. The good news is you can PWM the air pump to control the speed so you can slow it down as you approach the target pressure. The bad news is PID software control using the air pressure sensor and the auto-parts store 12V air pump may not be plug and play. Take a look at this post and tell me if this sounds like something you can do  :
http://playground.arduino.cc/Code/PIDLibrary   
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

mcozire

Hi everyone, thanks for your replies.

I was hoping to find LEDs powered by a small watch battery maybe? And enclose them in some sort of plastic, into a sphere shape, like a marble. ???

In relation to them clumping together, I could maybe get away with using one per tube. Or another solution?

Ok do in regards to controlling the air flow rate, and in turn controlling the LED lights going around, it seems quite complicated. I'm only new to arduino really.

How does the reservoir set up work/look like? Would this be a difficult operation?

Hi there, raschemmel

"You need to combine open loop off the shelf with mosfet switching of the air-pump based on air pressure sensor feedback"

I'm afraid I don't know what most of this sentence means :( I thought that the PWM would be the one to control the air, but I am not aware of the PID software control.

How much simpler would it be to connect an air pump, and make it go on/off?

Thank you all for your replies.

Robin2

Before you start thinking of pumps you need to figure out how much airflow you need (cu Metre / minute for example) and what pressure it needs to be at.

Many small cheap air pumps are designed for small flows at high pressure - such as for pumping car tyres.

My guess is that you need a substantial flow rate at a relatively low pressure.

You need to make up a sample of your tube (probably the full length so you get an idea of friction losses) and the encapsulation for the LED and try them. This is the sort of thing that will be difficult or impossible to figure out theoretically.

Assuming you have the air flowing in one end and out the other end of the tube how do you plan to get your LED capsules into the tube?

Perhaps you could post a diagram of what the final product should look like - a photo of a pencil sketch would be fine.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

raschemmel

Use PWM. It's not that complicated. Robin can help you . I'm a little busy right now.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Robin2


Use PWM. It's not that complicated. Robin can help you . I'm a little busy right now.


I think that's what is known as a "hospital pass".

What have I done to deserve it ?  :)

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

dave-in-nj

not sure if I understand the full concept.
a tall tube, a 'throwie' and a fan

http://www.element14.com/community/thread/4099/l/led-throwies-extend-their-life-annoyance


if you take a tall plastic tube, sized slightly larger than a pin-pong ball, put your throwie into that, you should be able to float the ball without too much problem.

the flow meters
http://www.lutz-jesco.com/fileadmin/data/dokumente/products/B-Flowmeter-TR01-RGB-L.jpg
have a ball with a tube that gets wider at it rises.  that way, more and more air will slip around it.  this is very desirable.

if you have a close fitting tube, you basically have a rifle barrel.  albeit with a pretty, lighted and soft bullet.

to test such a thing with a straigh tube, you could put in some clear tape up about 1/3rd of the tube, a couple layers thick, then less layers up to about 2/3

any blower will move enough air to make the balls rise.

if you create a plenum, you can open and close the door to release air and make the balls bounce up and down.
the smaller the release hole the better the control.






raschemmel

Sorry. I probably shouldn't have phrased it that way but I was a bit preoccupied by the fact that I just found out the insurance policy for my mother's house had the wrong address and we've been insuring the neighbors house since Oct, 2013 and we were uninsured. I got it straightened out though.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Robin2


we've been insuring the neighbors house since Oct, 2013 and we were uninsured.


oooooooHHHH      painfullllllllll

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

dave-in-nj


Sorry. I probably shouldn't have phrased it that way but I was a bit preoccupied by the fact that I just found out the insurance policy for my mother's house had the wrong address and we've been insuring the neighbors house since Oct, 2013 and we were uninsured. I got it straightened out though.

dave-in-nj


Sorry. I probably shouldn't have phrased it that way but I was a bit preoccupied by the fact that I just found out the insurance policy for my mother's house had the wrong address and we've been insuring the neighbors house since Oct, 2013 and we were uninsured. I got it straightened out though.


sorry to hear that,  post the code (don't forget to put it between the hashmarks) and we'll be happy to help you get the right pin addresses.

up-loading that will be a bit of a pain. highly recommend you keep any correspondence that shows they have made the change.


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