Monday, February 21, 2011

Arduino Stroboscope

I was watching TV a bit ago and playing with my model wind turbine from my fluids class and was having a good time playing with aliasing. From there, the obvious answer to my problem that I didn't really have was to build a stroboscope. This little tangent has resulted in a stroboscope capable of measuring rotational speeds from 577 to 30,000 rpm.

Before I get too far into the code and such, a brief description of a stroboscope is in order. A stroboscope is essentially a pulsed light at a known frequency. when the frequency of a rotating object matches that of the stroboscope, it appears to stand still. It is possible for the object to be moving at a multiple of the strobe frequency as well. for more info check out the interwebs or something.

Thursday, February 17, 2011

6 channel serial LED Dimmer w/ Arduino

While continuing research for senior project we came across the LanBox DMX controller. It essentially takes a hex string and converts it to DMX. Since the LanBox is expensive and we only have one, I wanted to make something that could function similarly for prototyping applications.

What I came up with was using all 6 PWM pins on the Arduino and assigning them intensities through a serial string beginning with "A"

Since allowable intensities varied between 0 and 255 I had the code break down the serial string into chunks of 3 characters. I dont know a whole ton about hex, but it would have been ideal.

So if you send the string "A255000255000122200"
channel intensities would be
  1. 255
  2. 000
  3. 255
  4. 000
  5. 122
  6. 200

The idea is that a whole string of all the instrument (LED) values would be sent in some sort of loop to control dimming operations so that minimal to no code would have to reside on the dmx device improving reliability of the system.

In the meantime, this is the code that I have come up with ideally I would like to be able to send information only on certain channels with some sort of identifier.

The exact code that is currently in use can be found after the break

Saturday, February 5, 2011

DIY temp controlled fermentation chamber from broken fridge.

(reposted from last year from Homebrewtalk)

So a couple weeks ago, my fridge broke. Since I live in an apartment, the landlord had a new one brought
3 flights of stairs by his crew. I saw an opportunity in this as it took those guys around 20 minutes to bring the new one up. I asked them if I could keep it and they said "sure go ahead." I now had this dead fridge out in my 30ยบ sun room that I needed to get working on. I already had a thermostat in my closet, but the closet has been proving too leaky to keep at a reasonable temp. So it worked out really well. 
Here's what I did. 

Friday, February 4, 2011

Closed loop evaporative wort chiller

Reading the forums, I noticed that a lot of people were feeling somewhat guilty about all the water that they go through chilling their beer. As a good engineer interested in thermodynamics, I decided that I would take a shot at tackling this problem. Since many of the people with the water issues were in warm climates with fairly warm water temperatures tended to be in the southwest, I decided that an evaporative chiller would be the easiest and most effective way to go.

My cooling system consists of the following parts connected in this order
1: High head pump (115' head, 650GPH))
2: Wort chiller (I used an immersion chiller but a counterflow or other isolated chiller would work as well)
3: Spray head (constructed out of PVC, 1/8" hole with flat surface to disperse water, I used a 14 Ga. copper wire)
4: Spray Column (used some circular duct from an old furnace install)
5: Reservoir (An old trash can in my case, I cleaned it, but it doesn't really matter)

The idea is to pump the water through the chiller and disperse it into a fine mist while moving massive amounts of air to evaporate as much water as possible. Each pound of water evaporated removes about 960 BTU from the environment in the form of a temperature drop. With evaporative cooling, it is possible to cool the working fluid down to the dew point so that means you can cool below the outside temperature which can be very significant in dry climates.

I have some more pics and details of the rig following

Prototype for Arduino control of Midi Dimmer pack

For my ME Senior Project this year, I have been assigned to work with the Galena Historical Society in Galena, Illinois. My Group has the task of designing three different exhibits for the museum. One exhibit involves the creation of a holographic type projection of Ulysses S. Grant and his wife Julia. The second exhibit is an interactive exhibit designed to highlight the famous Peace in Union painting, which will possibly be using this Arduino control, and a third hypothetical exhibit consisting of a rotating/translating display case. Write ups or more details on the display case and holographic projection may be posted later.

For the illuminated painting, the idea is to have a touchscreen with a digital version of the painting. Guests will be able to click on the individual figures to learn more about everyone contained in the painting. When a character is selected, they will be highlighted on the actual painting on the wall either by the addition or subtraction of lighting. Users will be able to navigate through various layers of details for each individual as they see fit, with the lighting following along.