How to Wear a Cabochon with an Irregular Shape

beaded-cabochon

WP-White-Bar-550x10

Now that members have made a bunch of fused glass cabochons this week, what can we do with them? You can make several cabochons and mount them on your own Medieval style gemstone covered book, hot glue it onto your stapler at work and really establish that one is yours, make some really shiny refrigerator magnets but jewelry is the most common application.

I encased my cabochon in a mount by free form hand weaving seed beads. This piece used different stitches and a strong nylon mono-filament thread. The beads are 11/0 size Czech glass and 15/0 size Japanese Miyuki glass. I encased the whole cabochon because the back of the fused glass was rough and uneven.

WP-White-Bar-550x10

beaded-cobochon-back

WP-White-Bar-550x10

Other methods to make jewelry with a cabochon with an irregular shape are:

  • You can stitch bead embroidery around the cabochon securing it onto a backing of leather or heavy fabric. This will be similar to my example but simpler in its execution.
  • Glue on a bar pin back to wear it as a pin.
  • Glue on a bail to wear it on a chain or cord. There are many colors, sizes and shapes of ready made jewelry bails.
  • Wire wrap the cabochon with jewelry wire.

Given the resources we have at the space, someone could even 3D print a setting for their piece and then cast it in metal!

 

 

 

 

 

28

07 2016

The Joy of Melting Glass in a Microwave Oven

microwave-glass-kiln-2016

WP-White-Bar-550x10

Samuel and Sylvia Sion brought in to last night’s member meeting an amazing impromptu class on fused glass. Glass usually has melting points higher than metal, yet there are these new miniature kilns that work inside of a conventional microwave oven! This makes fused glass work far more accessible and affordable from past days of using a larger plug-in electric kiln for hours. The time to melt an art glass cabochon was usually under five minutes with about 45 minutes needed for cooling. The larger kiln fit several pieces at once.

The microwave being used for glass fusing needs to be dedicated to art use only and never used for food again. (Cadmium and other pigments used for colorants are toxic, so this is a needed safety precaution.) Care needs to be taken to not overheat the microwave and destroy it, so letting the door stand open and the unit cool off between rounds of fusing glass is needed. Also, microwave kiln shelf paper needs to be placed on the base of the kiln to keep glass from melting onto the surface the kiln and destroying it. Heavy weight welding gloves worked as oven mitts to transfer hot kilns and the kilns rested safely on our ceramic fire bricks to cool.

Glass specifically made for fusing needs to be used for projects, like the brightly colored Dichroic glass example I made below. Dichroic and fusing glasses are the shiny, beautiful art glass pieces you always see in jewelry at art fairs. The price for making them yourself is very reasonable with this new method; you can buy enough to make several pieces for $20-$30. The kilns and tools to get started are being added to the small metals area and will be available within the following weeks.

WP-White-Bar-550x10

microwaved-dichroic-glass

27

07 2016

July Beer Church

The opening round

The opening round

In this month’s edition of Beer Church, the bombers flowed smoothly as we started off with the beer tasting:

After several rounds of tasting, we headed to Brew & Grow to start on our Brown Ale.  If you’ve never gone to Brew & Grow, this brew shop will have everything you need to start your own batch of beer from start to finish.

Grains

Grains

Gathering our ingredients entailed grabbing a cart with a bucket and scale attached and digging through our recipe book to catch all of our various grains needed for the mash.  We also grabbed some yeast and hops pellets to finish up our collecting.  Of course when you go to Brew & Grow you can sample some of their brews while you shop.

Wort Prep

Wort Prep

While the wort was being prepared I then decided it was grilling time!

Roll burgers into balls

Roll burgers into balls

Using a 75% / 25% fat mix, the beef was rolled into giant meat balls for smashing.

Smash into patties

Smash into patties

Once the burgers are made into balls, it’s time to smash them down and evening out the edges to make solid patties that will not disintegrate or crumble on the flame.  Salt, pepper, cajun seasoning were added on both sides of the burger.

Grill, flip only once and add cheese

Grill, flip only once and add cheese

Once the charcoal (which was started before the burgers were started) turns white, the lighter fluid should have burnt off and the grill is ready for use.  Toss on the buns to toast them but pay attention or they can scorch to a crisp.  Toss on the burgers with a spatula and note that the center is the hottest area so burgers are susceptible to scorching if you’re not careful.

The payoff: CHEESEBURGER!

The payoff: CHEESEBURGER!

Medium Rare

Medium Rare

Add condiments if necessary, and avoid shrinkage by removing the burgers before they are charred to a crisp.  Grill flame can get up to 500 degrees, so watch out or you or your food may get burnt!

IMG_8772

Back in brewing land, while the mash was settling, the kettle was loaded with water and lit to reach 190 degrees.

IMG_8778

After letting the wort settle, it was time to separate the sugars from the grain.

IMG_8779

In sparging we rinse the grain with hot water that is about 170 degrees, using the wrong temp can result in unwanted consequences!

IMG_8786

After the wort is in the kettle we turn back on the turkey fryer in order to begin the sterilization process and killing off bacteria.  As we mix the wort with a giant paddle, the heat coming from the turkey fryer singes everyone’s shins.

Pumping wort to carboy

Once the wort is heated up, we then cool it down by pumping cold water through the copper coils to bring the temperature back down.  Once the temperature drops, we then pump the remainder  through a tube into the carboy.

Here our decision to use pellet hops cause a lot of blockages in the tubes.  Using a mesh or filter bag on the pellet hops may have prevented some blockage but we were able to get most of the wort out into the carboy and did not smash it.

The ring of shame

The ring of shame

From last Beer Church we got to this final end stage and this handle failed causing the carboy to fall and smash all over the shop floor.  We were not to be tricked again and employed a harness setup to prevent any dropping.

Overall another successful Beer Church, we now have beer in progress which will be ready to be tapped soon.  Next iteration will use Creeping Charlie as the bittering agent in lieu of hops so it will be interesting to see how these two beers compare when it’s time.

If you are interested in beer or brewing, make sure to stop by next month’s edition of Beer Church!

19

07 2016

Configuring Pi 3 with a TFT touchscreen and GPIO buttons

A while back I built a pair of sound-reactive LED towers which were on display a few times, at some local Chicago events.

To plug into the DJ mixer output required a relatively expensive device to get the stereo signals (with external gain control) seen by a computer running processing.org as a microphone input.  Also, it was a relatively bulky affair to have yet another laptop sitting next to the mixer when the artist wasn’t using it to make the music.

Recently I discovered that starting with the 3.1 release, Processing can now run on a Raspberry Pi and has built-in ability to manipulate the GPIO ports.  This blog entry highlights the release.  This is exciting news as now the laptop can be replaced by a Pi 3 with a small touchscreen.

Here is a video of the light towers in action.

The towers each have 8 panels with 60 individually addressable RGB LEDs.  These pictures show off more of the visual esthetic and the cutaway view reveals something of the construction.  The LED strips are hidden in a channel in the wood supports which side illuminate acrylic panels (backed with just a strip of white cardboard).  The acrylic is impregnated with a diffuser which reflects the edge-lit light 90 degrees to exit out of the faces of the panels.  The white cardboard reflects the 1/2 of the light that would otherwise be directed inwards.   The acrylic is produced by Evonik and is called Acrylite EndLighten.  The towers themselves only require 110 VAC power.  The data frames to control the LED strips are sent wirelessly from the processing script using an Open Pixel Control  module which maps points on the processing screen into frames sent to a Fadecandy server running inside a OpenWRT Wifi device which is then physically connected to a Fadecandy board.  I used TP-Link TL-MR3040 WiFi devices to run OpenWRT and added the Fadecandy server application into the img file used to reflash the WiFi devices.  The Fadecandy GIT repository can be found here.

IMG_1689 IMG_1682

This is the assembled Raspberry Pi 3 w/ 2.8″ TFT Capacitive Touchscreen mirroring the HDMI frame buffer in a Zebra case without the top cover.

Pi 3 w/ 2.8" TFT Capacitive Touchscreen HDMI framebuffer

There were a lot of possible paths to follow in getting this build working the way I wanted it to be.  Most of my Google searching turned up outdated examples, particularly due to the changes introduced in the 4.4 kernel with /boot/config.txt use of overlays.  Adafruit had this very nice looking tutorial of how to get the touchscreen working with their version of the Jassie Raspbian os image.  The inclusion of how to use FBCP was of particular interest as mirroring the HDMI output is important for displaying processing scripts with the 2D or 3D graphics libraries.  Their Raspbian image was based on an older kernel and updating the os (sudo apt-get update; sudo apt-get dist-upgrade) turned out not to just work.

After much tinkering, these are the steps that worked for me.  (note that I working with OSX 10.11)

  1. Download the latest Raspbian Jessie image here.
  2. Extract the .img file using “The Unarchiver.app” as opposed to the built-in “Archive Utility.app” as I saw many comments that the default app caused issues.
  3. I chose a 32GB Samsung EVO Plus (model MB-MC32D) micro SD.  It has a red background.
  4. Flash the SD card with the extracted image file.  Instructions for doing this can be found easily.  I used the following procedure:
    • open a terminal window and change to the directory with the extracted image file
    • $ diskutil list
    • note the device path of the SD card (eg: /dev/disk4)
    • unmount the SD card, replace disk4 with what was discovered in the previous step
    • $ diskutil unmountDisk /dev/disk4
    • flash the SD card, again update rdisk4 and also make sure the if= filename is correct
    • $ sudo dd if=./2016-05-27-raspbian-jessie.img of=/dev/rdisk4 bs=1m
    • this will take at least 5 minutes to complete, but it is possible to see some status without interrupting the transfer, by pressing ctrl-t
    • exit the terminal window and eject the SD card
  5. Insert the SD card into the Pi and hook it up to an HDMI monitor.  You will need a keyboard and mouse as well.
  6. Open a terminal window
    • disable power management for the onboard WiFi module for stability
    • $ sudo nano /etc/network/if-up.d/wlan0
      #!/bin/bash
      iwconfig wlan0 power off
      
    • $ sudo chmod +x /etc/network/if-up.d/wlan0
    • $ sudo raspi-config
    • select Expand Filesystem and reboot
  7. Configure the WiFi as usual from icon at the top of the desktop
  8. Open a terminal window
    1. install updates
    2. $ sudo apt-get update
    3. $ sudo apt-get dist-upgrade
    4. install build utility
    5. $ sudo apt-get install cmake
    6. fetch the FBCP source, compile and install
    7. $ git clone https://github.com/tasanakorn/rpi-fbcp
    8. $ mkdir ./rpi-fbcp/fbcp/build
    9. $ cd ./rpi-fbcp/fbcp/build
    10. $ cmake ..
    11. $ make
    12. $ sudo install fbcp /usr/local/bin/fbcp
    13. configure the touchscreen by uncommenting, changing or adding the following config entries
    14. $ sudo nano /boot/config.txt
      # match console size
      framebuffer_width=640
      framebuffer_height=480
      
      # force 640x480 VGA on HDMI
      hdmi_force_hotplug=1
      hdmi_group=2
      hdmi_mode=4
      
      # 2.8" Capacitive 320x240 Touchscreen
      dtoverlay=pitft28-capacitive,rotate=90,speed=80000000,fps=60
      dtoverlay=pitft28-capacitive,touch-swapxy=true,touch-invx=true
      
    15. expose touchscreen events
    16. $ sudo nano /etc/udev/rules.d/95-ft6206.rules
      SUBSYSTEM=="input", ATTRS{name}=="ft6236", ENV{DEVNAME}=="*event*", SYMLINK+="input/touchscreen"
      
    17. select an easier to read console font
    18. $ sudo dpkg-reconfigure console-setup
      • UTF-8
      • “Guess optimal character set”
      • Terminus
      • 6×12 (framebuffer only)
    19. remove extra GLES library see this issue
    20. $ sudo aptitude remove libgles2-mesa
    21. install processing
    22. $ curl https://processing.org/download/install-arm.sh | sudo sh
    23. disable auto monitor-off
    24. $ sudo nano /etc/lightdm/lightdm.conf
      xserver-command=X -s 0 -dpms
      
  9. Reboot

The touchscreen should now display the 640×480 desktop scaled down to the 320×240 PiTFT screen.  This makes things look less crisp but has the advantage that connecting to an external HDMI display will work and that most apps need the larger dimensions be usable.  Note that many HDMI displays will not be able to handle a 320×240 HDMI signal.

FBCP stands for frame buffer copy, which rescales and mirrors the HDMI framebuffer (/dev/fb0) onto the PiTFT framebuffer (/dev/fb1)

The version of the 2.8″ PiTFT I got from Adafruit, comes with 4 buttons and I created this test Python script to demonstrate not only how to use the RPi.GPIO library, but how to manipulate the PiTFT backlight (so as to not burn-in the screen), use multi-threaded event handlers, and shutdown the os to safely disconnect the power.

I created this script as: /home/pi/pitft_buttons.py  (chmod +c pitft_buttons.py to make it executable) and test by typing ./pitft_buttons.py.  Note that pressing the bottom right button (#27) will ask for authentication for powering off the Pi.  See below to set this script running as a service, in which case, the user will not be asked for authentication.

#!/usr/bin/env python2.7

# example code tested with Pi 3
# Raspibian Jassie (4.4 kernel): https://www.raspberrypi.org/downloads/raspbian/
# Adafruit 2.8" Capacitive Touchscreen: https://www.adafruit.com/products/2423
# for running on startup see: https://learn.adafruit.com/running-programs-automatically-on-your-tiny-computer/systemd-writing-and-enabling-a-service
# make sure to update the ExecStart= entry in the Adafruit script after copying from the example

import subprocess
import time
import RPi.GPIO as GPIO

# list of BCM channels from RPO.GPIO (printed on the Adafruit PCB next to each button)
channel_list = [17, 22, 23, 27]
backlightOn = True

# event handler to toggle the TFT backlight
def toggleBacklight(channel):
    global backlightOn
    if backlightOn:
        backlightOn = False
        backlight.start(0)
    else:
        backlightOn = True
        backlight.start(100)

# event handler to manage button presses
def buttonEvent(channel):
    startTime = time.time()
    while GPIO.input(channel) == GPIO.LOW:
        time.sleep(0.02)
    print "Button #%d pressed for %f seconds." % (channel, time.time() - startTime)

# event handler to manage Pi shutdown
def poweroff(channel):
    startTime = time.time()
    while GPIO.input(channel) == GPIO.LOW:
        time.sleep(0.02)
    if (time.time() - startTime) > 2:
        subprocess.call(['poweroff'], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

# initialize GPIO library
GPIO.setmode(GPIO.BCM)
GPIO.setup(channel_list, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(18, GPIO.OUT)
backlight = GPIO.PWM(18, 1000)
backlight.start(100)

print "Button #17 exits."
print "Button #22 toggles the TFT backlight."
print "Button #23 displayed the time the button is pressed."
print "!!! Pressing button #27 for at least 2 seconds, powers down the Pi !!!"

GPIO.add_event_detect(22, GPIO.FALLING, callback=toggleBacklight, bouncetime=200)
GPIO.add_event_detect(23, GPIO.FALLING, callback=buttonEvent, bouncetime=200)
GPIO.add_event_detect(27, GPIO.FALLING, callback=poweroff, bouncetime=200)

try:
    GPIO.wait_for_edge(17, GPIO.FALLING)
    print "Exit button pressed."

except:
    pass

# exit gracefully
backlight.stop()
GPIO.cleanup()

To install pitft_buttons.py as a service,

# pitft_buttons service file, start a daemon on startup
# file: /etc/systemd/system/pitft_buttons.service

[Unit]
Description=Start PiTFT buttons daemon

[Service]
RemainAfterExit=true
ExecStart=/usr/bin/python -u /home/pi/pitft_buttons.py

[Install]
WantedBy=multi-user.target

Run a processing sketch from a script or from a terminal window or ssh session.
$ DISPLAY=:0 processing-java –sketch=/home/pi/HelloWorld –present

16

07 2016

4th of July – BBQ o’clock!

A long time ago a friend moved to Chicago and I invited her to my BBQ.  When she got there, she was very confused.

“This is a cookout!” she said.  Not understanding, I tried to figure out what she was talking about.  Apparently in the south, BBQ’g means you take a smoker and smoke meat low and slow for long periods of time and a cookout is when you take your grill and cook some hamburgers and hot dogs.

Fast forward three years, it’s now 12:45am and it’s time to start BBQ’g.  Today’s recipe is 18.5 pounds of pork shoulder otherwise known as Boston Butt.

What is Pork Shoulder?

Boston Butt / Pork Shoulder

A staple of American barbecue, pork shoulder counts itself as one of the most forgiving of meats.  If you smoke it for too long, the meat tends to dry out some but with enough BBQ sauce, you won’t need to worry.  From a default, I usually serve my pork shoulder with no BBQ sauce as good BBQ doesn’t really need it but BBQ sauce is not faux pas and will bring more complexity to the dish.

Starting your fire

To start your fire you will need

  1. Charcoal briquettes
  2. Hickory Wood Chunks (read chunks, not chips)
  3. Water
  4. Chimney Starter

IMG_7934

What you will need to do is lay the charcoal and hickory into the coal pan of the smoker.  Once placed, the chimney starter will be lit from the bottom to start the flame without lighter fluid.  You can either use newspaper or Weber ignition cubes to get the fire started.  The goal here is to get the coals in the chimney smoking and red hot so that you can dump them into the coal pile below.  Avoiding lighter fluid is important here because the gasoline/lighter fluid smell will get into the food which will make for some unappetizing eats!

Meat Preparation

IMG_7944IMG_7945IMG_7943

While the chimney is smoking, grab some pork shoulder and lightly apply yellow mustard.  The mustard will work to hold the rub to the pork shoulder while it smokes to help the rub caramelize and give the pork shoulder nice bark.  Once light mustard is applied, add on the rub on both sides of the pork shoulder

IMG_7938

Once the chimney is on fire you will need to exercise caution to pick up the chimney starter, remove the grate and dump it onto the bed of coal and wood below.

IMG_7939

By dumping the hot chimney coals to the pile below, it will ignite the rest of the coals without the use of lighter fluid and sustain itself for a prolonged period of time.

IMG_7935

Next up fill your water pan with a watering can, this will help regulate temperature as well as generate additional smoke.

IMG_7942

Once you have the smoker up and running you will have smoke from coal and wood that will run for a good 5-7 hour stretch before the temperature starts to diminish.

IMG_7946IMG_7947

The trick with smoking meat is to try to keep the temperature low and slow.  Too much heat and you will end up burning the meat.  Not enough heat and the meat will not get past the stall and will not be as tender as you need it to be.

stall

Source: Amazingribs.com

Smoking meat is somewhat of a marathon.  The target temperature to hit with most meat is about 200 degrees F.  At this point, meat tenderizes and reaches peak flavor.  While it’s still possible to eat pork shoulder at 180 or even 190F, I’ve definitely seen that breaking past 200F will yield great results.  Some people will go 215F but risk the meat drying out when smoked for that long.  When smoking meat applying some apple cider with a spray bottle about 5 hours into the smoke.  You can also wrap the pork shoulder in foil and spray the shoulder, this Texas Crutch will help speed up the process and shave off a few hours off the total smoke time.

After 6 hours the coals will die down, so at that point apple cider vinegar will be misted on the shoulder and you can either finish it up in the oven or load a new chimney or charcoal and keep going.  It’s up to you if you want to wrap the pork shoulder or let it ride on the smoker.  Since I was in a time crunch I decided to deploy the Texas Crutch and bring the pork shoulders to the finish line.

IMG_2624IMG_2627 IMG_2631

Once the pork shoulder eclipses 200F, it is time to let it sit in a tray and cool off and rest.  This resting period lets the pork shoulder reabsorb some of the juice that may be in the foil to get juicier pork shoulder.  Once the shoulder is rested 45 minutes to 1 hour, take your favorite set of bear claws and start ripping up the pork.  You’ll find it therapeutic but if you have no bear claws you can use your bare hands or two fork method.  Since I got a set of bear claws I’ve never had to turn back.  After you’re done, it’s ready to go, make sure to mix up the pork shoulder and make sure the juice gets on a lot of pieces.  One 9lb of pork shoulder should be able to feed 20 people or so, so not bad in a long night’s work.

05

07 2016

CNC Birdbath Bowl

I recently completed my most ambitious ShopBot project to date: casting a concrete birdbath bowl in a mold that I CNC’d. This was also my first attempt at producing a video about a project as I’m working on it. Watch the video below:

05

07 2016

Of Biscuits and Pirates

A lively assist!

A lively assist!

Hark! Saturday eve a few weeks past our dear “Spoons” (AKA Gerald Gayares) held a feast of hearty proportions! Eggs were broken, strawberries destemmed, chives snipped, and oh the mushroom boiling! He was valiantly assisted in this effort by Shelly “Pickles” Gayares and a smattering of the Mighty Crew of PS:One who were drafted to the event.

 

A Hearty-har-har Hardtack

A Hearty-har-har Hardtack

Ye may be asking then: how to can I provoke such a feast of glory of mine own?

1: Firstly ye must be WISE! Tender biscuits and crispy yeasty waffles are not the product of a few hours of careless abandon. Ye must plan for your journey so as to have on hand all the necessary apparatus, provender, and mates to accomplish your goal. Spoon’s yon tender-crisp waffles had begun some twelve hours in advance! Supplies were amassed over the whole of the week. Mark yer book of accounting with a list of needs and wants. Timing be’ critical.

pirated-me

Gather A Crew!

2: Secondly ye must be BOLD and Seductive! Declare yer intentions. Claim thy time and place with loud hollering. Alert thy comrades old and new. Do ye be thinking that a person shall attend the quiet church mouse squeaking out a proclamation of a tidy crumb to be nibbled? NAY I say! Go instead to the weekly meeting and bellow out “FEAST” so that all may know of yer intended soiree. (In our case it be more like a sortie…) Then go to the town square (Google Groups) and post a list declaring your nefarious goal along with any needs of supplies and crew. If-n’ ye be the timid sort or of short time then promote yer-self a good first mate to advocate for your cause. There be’ many a good mate to be had at this port, especially for the cause of a good feeding.

 

pot-o-mushrooms-before

Pot-O’ Mushrooms

mushroom-gravey-after

Pot-O’ Victory

3.Thirdly ye must be STRONG! The day of yer tasty battle will not be kiddy pools and microwaves. There will be fire, a broad side of gloriously dirty dishes, and absent baking soda all bent on thwarting yer merrymaking. Command thy crew with vitality and they will follow you to the depths of this Cursed Sea and to the grocery store no matter what behemoth lays in wait, as long as they get fed.

 

 

 

 

 

With the aforementioned application of Wisdom in planning, and Boldness for comrades, and Strength in application ye shall have all a person needs to attain a tasty conquest. This is after all a maker space: Just do it.

waffly-goodness

Aged Yeasty Waffles of Joy

16

06 2016

100th NERP Tonite! Embedded GUIs part 2 of 2: Qt

For the 100th NERP Meetup (Yea!), we’ll have the second of a two-part discussion of embedded GUIs on small Linux devices. Qt is much more than a GUI library. Tonight Ron Olson will share some wisdom on the Qt application framework. Ron tells me that Qt promises a lot, and it delivers. Sounds good to me!

Ron says “I figured the main thrust of the talk would be Qt, how it works, its two main parts (C++, QML), and how it works with the BBB as well as a Qt project controlling an Arduino, all with an eye towards demonstrating the QML, and lightly, the C++ connection.”

After graduating from NYU’s film school, Ron took full advantage of his film and theatre background by becoming a software developer. For 24 years, Ron has been one of the developers that companies go to when they want to make their customers lives worse; he helped write the system to show commercials at MTV, worked on cancelled projects at an animation studio that went out of business, pioneered allowing you to lose your retirement savings on the web at Bankers Trust, came up with new ways to target ads to you at DoubleClick, did his part in the financial crisis at Goldman Sachs, and lately has been writing software to help your attorney remember when your trial date is.
Mostly in C++ and Java.

NERP is not exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago. Find NERP and Pumping Station:One at

http:// www.meetup.com/NERP-Not-Exclusively-Raspberry-Pi/
and
http://pumpingstationone.org/

Doors open at 6:30pm. NERP is free and open to the public. Ed Bennett ed @ kinetics and electronics com Tags: electronics, embedded, NERP, Open Source, raspberry pi, hackerspace, Beagle Bone, Pumping Station One, programming, Qt

06

06 2016

So you want a smart thermostat but don’t have a ‘C-Wire’

Background

You are rent/own a condo/apartment and you want a smart thermostat to keep track of your spending on heat/cool, or want a thermostat with remote sensor support.  You pulled the current thermostat off the wall and looked at the wiring and you have a 4 wire system (R, Y, G, W) but no ‘C-Wire’ and the thermostat you want to use requires a ‘C-wire’ but you don’t have one.  You look at the Ecobee3 that supports 4 wire systems but you don’t have access to the HVAC unit because its in a locked closet/on the roof and you don’t want to have to deal with your landlord/association to get access to it as it probably means having to spend a few hundred more bucks to have a professional installer do the work.  Don’t worry though you can still have that smart thermostat you want, but it’s gonna be a little ugly but you can still have what you want.

What is a ‘C-Wire’ and why do thermostats need them?

HVAC control systems are based on 24V AC control signals, in a combined heat/cool unit you have 4 or 5 wires (we are going to concentrate on the 4 wires here because if you had 5 then you probably would not be searching for a solution for this problem.  In a 4 wire system you have one common supply wire (R) when the thermostat wants to request a function from your HVAC unit it connects one of the other 3 wires to the common supply wire to complete the circuit for that feature. 4-Wire ‘pins’

  • R – Common supply line
  • G – Fan request
  • Y – A/C Request
  • W –  Heat Request

The 5th wire in the system is C this is the second common wire and is connected to the other side of the 24V transformer in the HVAC control system, its used to power accessories such as a thermostat.  Your system probably does not have a C-Wire as your thermostat is battery powered.  ‘So how does the Nest manage to work without the c-wire?’ I hear you ask, well it scavenges power to charge an internal battery/capacitor by using G wire in short bursts to complete its charging circuit.  ‘Ok so why don’t other thermostats do that?’ Well if your HVAC system is to sensitive it can cause your fan to turn on and off for very short periods of time, this can be very bad for the longevity of your blower motor.

Imagine this simplified control board diagram:

 

hvac-control

So can’t I just hook up a second PSU to the thermostat and hook it up from R to C?

Short answer, no!  Long answer if you are are VERY VERY VERY sure that the phases of your HVAC unit and the outlet you use are in sync it is a very bad idea to just hook up a second PSU to the system, you will damage both your thermostat and HVAC control board.

So what is the solution?

To get the system to work you have to create an interface that will mimic a thermostat to the HVAC control board and mimic a 5 wire HVAC control board to your smart thermostat.  To do this we need 3 relays with a coil voltage of 24V AC, a 24V AC PSU, some screw terminals, a proto-board and some form of case.  I used the following relays and PSU:

  • Relay RT314524  – Newark P/N 03P2422
  • Triad Magnetics WAU24-200 – Newark P/N 96M0310 (Note this item is discontinued once stock levels are depleted so you may need to find an alternative)

Once you have the parts you need to assemble the following circuit:

 

interface

Put it in a case and hook it up to your system.  Now you can enjoy your 5-wire requiring thermostat with your 4 wire controlled HVAC system.

 

IMG_0545

IMG_0546

You should also design a better wall mounting solution into your case so you don’t have to use blue painters tape to hold it to the wall, this will be being rectified with some double sided foam mount tape in the future.

05

06 2016

House Number

This was a simple project that took a lot longer than it should have. Nothing fancy, just numbers welded from 1-1/4″ mild steel stock and 3/32 rods. Some of you may have seen me tackle it a few months back in the hot metals area. Due to a total lack of free time, I only now installed it on my house.

20160529_140934(1)

The rods are painted a color approximating the brick, making the numbers “float” about 1-1/2″ from the face of the wall.

31

05 2016