Sunday, June 17, 2018

Heating element testing

I decided that I would finally test a 10cm length of 36 AWG nichrome wire with a current limited supply of varying voltages.  Since my windmill generates under 1 Amp of electricity I decided to use an LM317 integrated circuit to fix the current at a max of 220mA.  I put an LM317 in a bread board and attached its output to a 10cm length of 36 AWG nichrome wire (from the hair curler heating element).  Below is the circuit diagram for my LM317 set to limit current to 220mA:

Using the LM317 as a current limiter
Need to connect the 3 terminal chip as below:

To calculate the resistance that you need to limit the current to what you want:

In an effort to maximize the effectiveness of the heating element I decided to test different thicknesses (or gauges - higher the gauge thinner the wire) of Nichrome wire to see which would work best (produce the most heat with the power produced by the windmill - just under 2 watts). With this in mind I ordered 40 and 38 AWG Nichrome wire from Jacobs Online . They mainly sell Nichrome wire for making foam cutters and igniters for model rockets (the larger scale rockets). They are fairly inexpensive since you can order lengths as short as 10 feet – for $6 I got 10 feet of each of the 2 sizes I mentioned before (if I had wanted 100 feet of each I think it would have only cost me around $12 – better deal but I just don't want all the excess around).

Some basic notes on Nichrome wire:
  • higher gauge (thinner) = higher resistance per unit length and heats up at lower power (less current)
  • coiled wire produces higher temps than straight wire (with the same voltage and current)
More in depth info on nichrome wire take a look at the Wikipedia Page for Nichrome Wire

Resistivity of 1 foot straight Nichrome wire at room temperature:
AWG Ohms
40       70.2
38       42.2
36       27.0

Need some type of temperature resistant insulation between the wire  and the aluminum casing to prevent shorting out the current to the wire (do not want the wire in direct contact with the aluminum since it also conducts electricity). Insulation: Mica sheet, fiber glass fabric (welding supply, car body work with Bondo)

Ni-chrome Wire Calculator
Gives you some ideas of what you need even though the lowest temperature on the calculator is 400 degrees Fahrenheit.

If average wind speed is 15mph – which produces 220mA at about 9volts. That gives us our average power available. Ohms law states V=IR rearranging we get R=V/I:
R = 9v/0.220Amps
R = 40.9 Ohms

So, with the windmill running with a 15mph wind producing 9 volts with 220mA (which is just under 2 wattS – P=9v*0.22A) if we use a length of wire with 40.9 ohms resistance it should use up all the power. Yes, I know its not perfect reasoning since resistance increases with increasing temperature in the wire but I'm just trying to get an idea of what I need before I begin trying things.

Project Neurofeedback: Going a bit further with EEG hacking (Part 3 - smaller unit)

Remove the TGAM1 Board

(This step is optional – I just wanted to remove parts that are not actually used and free up space. If you do this then you also need too add a 3.3v regulator circuit to the power supply, same as I did)
Separate the TGAM1 Board from the main board in the Mindflex Headset. This reduces the size significantly – Bluetooth board will fit with room to spare.

  • Cut headers attaching boards
  • Desolder and remove cut header pins
  • Keep connections to (Header P1 connections on data-sheet)
    • Ground (electrode)
    • Reference (electrode)
    • EEG (electrode)
Adding a 3.3v regulator, with filter caps, to the power supply (3 x 1.5v AAA batteries in series).
3.3v regulator board (strip board)
  • linear voltage regulator
  • filter caps

Tuesday, May 2, 2017

Project viEwMotion

The goal of viEwMotion is to facilitate communication for individuals who have difficulty expressing emotions due to inherent neurologic issues like Autism, Parkinsons, etc (conditions that make it hard express emotion outwardly and as a result for others to read emotion expressed by the effected individual).  viEwMotion will do this by interpreting real time physiological data acquired from a wristband which is then processed by a single board computer and displayed to allow others to see the persons emotional state.  This will have a profound effect on the ability of people to communicate effectively - changing how they experience and interact with the world around them (in effect changing the world for them and those they interact with).
viEwMotion is a wearable device (worn on the wrist like a watch), that monitors and transmits data to a mini computer which interprets the data and outputs it to a display worn by the individual.

Sunday, February 5, 2017

Project Voight-Kampff

My objective is to build a functional Voight-Kampff machine from the classic Sci-Fi Movie Blade Runner. 
Leon's test :

Rachel's test:

Currently, I'm working on developing the software, integration of sensors and the actual body of the machine.

I currently have this project entered in the Hackaday Sci-Fi Contest  (Voight-Kampff Project Page) and I plan to exhibit it at the Chicago 2017 Maker Faire.

I have much of the mechanics (arm raise, extension, and rotation of the eye sensor) worked out using servos and micro-controllers.

My current design calls for using a Raspberry Pi as the central processor for the VK. The sensors that I'm currently working on integrating are:
  • Melexis MLX90614 Non-contact Temperature sensor (for Blush response)
  • Raspberry Pi NoIR Camera Board v2
    • using software adapted from PyGaze to measure pupil dilation/constriction
  • Separate hand held module for test subject containing:
    • MAX30100 pulse ox sensor
    • Galvanic Skin Response Sensor
I aim to have it all contained in the classic VK machine with read outs from the sensors going to the 3 separate monitors (and the 2 LED Bar Graphs).

Tuesday, January 24, 2017

Project: A Maker Loupe

This project is also published on as Maker Loupe
Commercial Products that work - but don't meet goals and restrictions:
  • Dental Loupes (Links Comming)
What I've tried so far:
  • Simple Magnifying Glasses – hand held and fixed
    • need to be very close to object being viewed
  • Reading glasses (various magnifications)
    • higher the magnification → closer you need to be to what you are viewing
  • Binocular Microscope
    • works quite well but still need to be bent over the scope
    • a movable stage would improve its ease of use
  • USB Microsope
    • not much experience but they can have a bit of a delay (what you see can be a fraction of a second behind what is happening at the moment).
  • Video Scope – NTSC camera, lenses and composite display
    • works reasonably well
      • may be able to improve by moving view screen lower and angling it
 Project Goals/Objectives:
  • Comfortably working with small parts, components, etc. without having to be bend over or bring the parts close to my face.
  • More comfortable – better ergonomics
    • same as above
      • able to sit upright while working (not bending over)
  • inexpensive (under $100 or better yet, under $50)
  • hands free / wearable / light weight
  • Magnification (at least 2x)
  • Field of view (at least 3cm)
  • Depth (about 3cm, enough that working on projects does not lead to neck strain from holding position).
Project Restrictions:
  •  Price - affordable for most people
    • ideal is re-purposed parts 
Updates coming soon.