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Author Archive | Paul Badger

Dimensional data for the Rev P Wind Sensor

Some customers had requested the dimensional data of the Wind P sensor so I put this together. These dimensions apply to Wind P versions P4, P5 and P6. I will differentiate these different versions and the direction that I am developing this sensor in subsequent posts.

We moved to a smaller header (the two sets of five holes at the top, from the previous version of the sensor the P3. The purpose of these holes is to be able to detach the “sensing stalk” and solder in wires or even a connector. I’ll go over actually doing this in another post, including some photos. In any case the finer pitch holes makes this a little challenging. The mounting holes at the top are also a different diameter than the holes at the bottom. This was probably a bad idea and one I regret now, but it’s done.
The pdf of the dimensional data may be found at the bottom of the Rev. P Wind Sensor page.

RGBW COB LED driver board

         

We created a board for driving  RGBW COB (Chip-On-Board) LEDs. We also sourced some RGBW (red, green, blue, white) COB LEDs, and heatsinks to put together a complete LED lamp kit. The drivers are constant-current source drivers based up the same topology as a buck switching regulator, so there is very little heat generated by the drivers. The other advantages of the driver, and the reason that switching regulators have taken over the world, is that any voltage supply may be used (at or above 12V) without losing efficiency. In other words if the supply voltage is raised, the current draw at the supply is reduced while the current supplied to the LEDs will remain constant.

The COB LEDs however do get hot, and definitely need a heat sink. We put a thermistor on the board, with a voltage divider, so you can monitor the heat on the heatsink if you are using a microcontroller board.

We also sourced the COB leds and the heatsinks so we can provide this either as a complete kit or an complete assembly.

A great thing about the LED driver we found is that the LED AL8861 driver chip inputs can accept an analog input, as well as PWM, allowing you to build a nice variable color RGBW lamp with only four potentiometers. The driver board inputs work equally well with PWM outputs from an Arduino or other microcontroller, and dim easily from 0 to 100% in a nice linear curve. The driver board will accommodate either one or two COB LEDs with currents up to 600 mA.

There is also nothing to say that you couldn’t drive a whole host of other types of LEDs such as 24 or our 1 watt LEDs arranged in a 3 series x 2 parallel x 4 channels, or  120 5mm LEDs arranged in 3 series x 10 parallel x 4 channels. The mind boggles at the possibilities.

Some custom applications might include:

    • Controllable LED signage
    • Custom / DIY LED Lamps
    • Theatrical Lighting
    • Grow Lights
    • Colored Strobe Light Experiments
    • Impressive and blinding Halloween costumes

Specifications for the COB LEDs:

These are the specifications from the manufacturer for one COB LED.

Channel Volts Current Lumens
red 6-7V 350mA 200-220
green 9-11V 350mA 320-340
blue 9-11V 350mA 80-100
white 9-11V 350mA 320-340

We’ll have product links up as soon as get done editing the product pages. Also a discount code for the first few buyers.

Wind Sensors In Escape Rooms

We don’t always get to hear about what our customers create with our products, so when they reach out to us we are always giddy to see what they cook up. Key to Escape, an Escape Room based in North Carolina, put our Wind Sensor Rev. C’s in some prop LED candles and made them react to the user’s breath. By blowing out the candles in a certain order, they can unlock the next clue and proceed through the puzzle (see attached video). Well done!

We would love to hear from more of you on how you use our products. Please feel free to shoot us an email with your work and we’ll feature it here!

Calibrating The Rev. P Wind Sensor From A New Regression

I reprocessed some old data to add some software temperature compensation for the Rev. P wind sensor. The sensor itself has hardware temperature calibration built in, but the hardware compensation isn’t perfect.

You can see by these trend lines in this ADCunit vs static pressure graph that the curves diverge slightly at the upper end of the graph. I used the static pressure data from a pitot tube along with humidity and temp data, to convert the pitot tube data to wind velocities. I then set up a regression and derived an equation that matched the curve of the sensor.

I did the regression, solving for the output voltage instead of the wind speed, as I probably should have done. When the regression was done I had to factor the final equation, solving for the wind speed (in MPH) instead of for the volts, which is what the sensor outputs. This resulted in slightly less clear math, than it might have been, had I done the regression the other way around. I’m far from an expert Excel jockey, but knowing how to use the “Solver” in Excel makes me feel like at least I could play one on TV, after maybe a clean up and a shave.
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