Height of low pass filter

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Height of low pass filter

Post  jetty on Sun Sep 11, 2011 11:22 am

In installation I am obtaining different results with the quality of the laminar stream, with everything the same apart from the location of the various parts: pump, low pass filter and nozzle.

Pump is on the bottom, and nozzle is 2 feet higher. It turns out that in this configuration, the height of the low pass filter is important. With the filter at the height of the nozzle, laminar quality is poor, and placing it as low to the bottom as possible, quality is good.

Not sure why the filter is less effective higher up.
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Re: Height of low pass filter

Post  scrafy on Sun Sep 11, 2011 8:06 pm

Post pictures and maybe I can come up with an answer.

thanks!

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Re: Height of low pass filter

Post  jetty on Mon Sep 12, 2011 9:05 am

It was not so much of a question, more of a statement to help others, although it would be interesting to know why.

You wouldn't be able to see it from a picture as I have everything crammed in a 3 foot wide drum making it hard to see, as stuff is hidden by other stuff but it's pretty easy to visualize. Pump is at 0 feet off the bottom of the barrel, Nozzle is at 2 foot and bottom of filter is at 2 feet (both the level of the filter and nozzle inlets). In this configuration, filter has water in to the correct level but performance is poor, almost like there's no filter. Move the filter to 0 feet and performance is superb. Development was completed with all components laid out flat, hence the surprise when I put them in a drum.

On to final installation now and a 2nd nozzle. I have a 10 inch nozzle with a 9 foot distance, 4.5 foot height and perfectly laminar to the end (can get around 60 ft with the nozzle if I sacrifice laminar flow after 10 ft :-) ).

40W RGBW led lighting driven at 700mA per channel RGB (buck puck, so virtually no heat on the driver). Led mounted on a custom heatsink at the bottom of the nozzle, i.e. no fiber optic), using a perspex rod instead. Stepper motor cutter. Used Mario's air relief valve design (they work great by the way, a quick puff of air as the tube loads and they close off).

5 x 1-wire temperature sensors (Led heatsink x 2, outside, electronics and stepper motor x 2). BlinkM MaxM's which generate the color schemes and control signals for the LEDs.

Also have the 0-100% tank level indicators in place and diode based wind sensor (no moving parts to break).

Everything is controlled by Arduino and it's web based. I.E. I can control the system remotely by iPhone / Computer over wifi.

Very close to the end, and quite the journey.


Last edited by jetty on Mon Sep 12, 2011 9:07 am; edited 1 time in total (Reason for editing : Omitted the blinkM)
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Re: Height of low pass filter

Post  scrafy on Mon Sep 12, 2011 11:56 am

Sound so nice, what was the aproximate cost of everything?

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Re: Height of low pass filter

Post  jetty on Mon Sep 12, 2011 10:46 pm

Tough to say, haven't been keeping a close track. Bear in mind that the electronics are for 2 nozzles. Here are rough prices. Also, depending on where purchased and how resourceful you are, prices can vary.

2 x 55 gallon drums $20 (recycled from local hospital)
10 inch diameter drainage pipe 10 foot: $20 (scrap at local public works supplier)
2 X 1500 GPH Pro grade Pumps: $139 Home Depot
2 x Low Pass Filter: Approx $10
2 x 40W RGBW Led: $44.94 Mouser
6 x BuckPuck 3021-D-E-1000 $13.84 Future Electronics Inc. (3 per LED, White channel I've omitted)
1/2 inch Perspex Rod 6 ft $10 (not using fiber, LED mounted outside tube on bottom plate)
2 x Stepper Motor 12V 0.4A Unipolar $19.99
DiamondBack Arduino Wifi $78.75 (You could also use Arduino + WifiShield)
2 x Arduino Prototype boards: $15
2 x BlinkM MaxM: $25 (drives color sequencing on LED's via BuckPucks and additional inverting circuitry)
2 x Water Levels: MPX2010DP Pressure sensor $10.35, LM324N $0.50
(2 water levels seems strange as the tanks are connected, however as water flows, between the 2, you can get uneven levels as the water moves around. Personal preference, you can probably get away with one.)
1 x solid state wind sensor, $7.09 for INA126PA
Custom stepper motor circuitry: $20
Additional components for above $10-20
5 x DS18B20 Temp sensors: $5
2 x 24V supplies for LED's IP67 rated: $16
1 x 12V supply (IP76) for Microcontroller / steppers and other electronics: $16
1 x Solid State Relay: $30 (for switching 2 pumps) To build a fully opto-isolated remote socket
Various other stuff $30-$50
Plus time coding.

If there's enough interest I'll post circuit schematics, measurements, design of everything and code.

When buildling all this, I haven't gone for cheapest everything. Primarily I've been interested in functionality, modularity and ease of design. Where I have a choice of electronics versus doing something in software, I've chosen software if it doesn't compromise functionality. This all could have been implemented on a custom PCB, but it takes time and messing around, hence this approach. However because all of this is modular, things can be plugged into other projects too.
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Re: Height of low pass filter

Post  jetty on Sat Sep 24, 2011 3:54 pm

Have now replaced the Diamondback Arduino, with:

Arduino Mega 2560: $59.95
Cupperhead WiFi Shield: $57.75

The reason for this is that despite everything working I only had enough program space with 32K of flash to just manually control things via a web browser by the time the wifi, temperature, stepper libraries etc. were loaded on to the board, the Wifi library takes up half of the board space.

Automating things, requires at least 2-4K extra, hence the switch to the larger board, and then requiring a separate wifi board. Bonus, there's lot of spare pins for controlling other stuff too and more RAM.
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Re: Height of low pass filter

Post  karsten.bojesen on Sun Feb 05, 2012 9:27 pm

Hi Jetty,

Can you post circuit schematics for your LED setup?


Brgrds

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Re: Height of low pass filter

Post  jetty on Sun Feb 05, 2012 9:50 pm

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Re: Height of low pass filter

Post  karsten.bojesen on Sun Feb 05, 2012 9:53 pm

Thanks! Sorry for the inconvenience. ;-)

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