Monday, July 28, 2014

2014-07-27 (Su) Conductive Paint Experiment


The response to my conductive paint experiment on sites like Hack A Day and Instructables.com has been phenomenal so I have kept experimenting with different parameters. Today may be the last day but then again someone may suggest something else that makes me want to pick up and try some more. I won't force it either way.

Someone on Instructables suggested mixing graphite powder with paint medium which eliminates paint pigments which may interfere with the resistivity. As it would happen, my roommate, who gave me the idea to start this experiment, had some gel medium which she donated to the experiment.

Enough background.
----------

Black acrylic paint was purchased but the pigment is unknown. Ideally the pigment would be carbon. A swatch was painted on Friday and allowed to dry. No measurable resistance could be measured on the pure paint. The goal is to test two more substances with graphite powder in the same manner as the first three experiments.

 Materials for this experiment

Graphite powder was added to two jars. Black paint was mixed into the first jar at a ratio of approximately 1:1 by volume. The mixture was stirred with a toothpick. Once mixed a single heavy line was drawn before the toothpick was wiped off in the jar and allowed to dry next to the sample.

Amount of graphite in each jar
Line and toothpick covered in paint and graphite powder

Gel medium was added to the second jar at a ratio of approximately 1:1 by volume. The mixture was stirred with a toothpick. Once mixed a single heavy line was drawn before the toothpick was wiped off in the jar and allowed to dry next to the sample. The gel medium and graphite powder required more laborious mixing than the black paint and graphite powder.

Open jar of gel medium
Adding gel medium to graphite powder

Mixing gel medium and graphite powder

Lines and toothpicks drying

The samples were allowed to dry for five hours. No resistive reading could be taken from the gel and graphite powder after hours of drying. The black paint and graphite powder had acceptable readings.

Toothpick
Line
Pure black paint
∞Ω
∞Ω
Gel medium and graphite powder
∞Ω
∞Ω
Black paint and graphite powder
997
164Ω

Testing gel medium and graphite line

 Testing gel medium and graphite toothpick

Testing black paint and graphite line
 Testing black paint and graphite toothpick

Journal page


The rest of the posts for this project have been arranged by date.

A list showing of all the final posts of COMPLETED projects.


This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

Sunday, July 27, 2014

2014-07-26 (Sa) Sous Vide Oven V2.0

I was very happy with my first sous vide oven controller and my mom was pretty excited to hear about it. I've mentioned this before. On Saturday I gave her my first model, which is dead simple to operate and has a temperature probe that is easy to disconnect. She was pretty excited to use it. We went out and bought a hot plate identical to mine so her setup even matches the instructions I wrote for her. Part of the appeal for her is that she can prepare several single serving meals at a time and just seal them up to cook at her leisure.

Here's hoping she enjoys the oven controller!

Enough background.
----------

To supply the controller with DC power an extension cord was cut so the socket end could be fastened in place with the lever-style wire nuts and a DC power supply could be plugged in. A 5VDC power supply was salvaged from an old mini USB charger. 5VDC, 1A. The power supply had the wires stripped and a volt meter was used to determine the polarity. As expected the positive lead was inside the negative which is standard for coaxial cords. The AC socket wand DC adapter were connected and secured with zip ties. The DC wires were stripped again to get more distance between the tips since they will be wired to different locations. The shielding wire was twisted to bundle it neatly and covered in shrink tube. The DC supply was wired into the circuit according to the schematic sketched earlier.

Extension cord to be sacrificed

Socket end of extension cord with six inch tail

Power supply being sacrificed

Testing polarity of DC supply in a different extension cord

DC supply attached and secured to power socket

Trimmed ties of power supply and extension cord

DC wired into circuit

Schematic of circuit with DC power supply

Once the wiring was done the warning sticker was removed form the plug and the unit was plugged in. The temperature probe was installed and held against a 4Watt incandescent light bulb but it would not light up. Continuity and voltage testing was performed to ensure that all the connections were correct and solid. A DC examination showed that the new power supply was functioning but the temperature controller was outputting a DC signal of its own. The 5VD power supply was removed and the SSR was wired as intended by the manufacturer. No instructions came with the temperature controller kit so more research should have been done to avoid the extra work and expense. The unit was plugged in and tested again. The unit functioned well. It hit the target temperature without exceeding it and held steadily. The frequency of the PWM (Pulse Width Modulation) was much lower than expected but done to accommodate AC power which may function unreliably at high frequency, such as over 50Hz. The unit was fully assembled and a rotating shot was taken at full camera resolution using video and still shots.

Frequency of PWM

Rotating view of unit

To do:
  • Sketch new schematic
  • Waterproof thermometer


The rest of the posts for this project have been arranged by date.

A list showing of all the final posts of COMPLETED projects.


This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

Saturday, July 26, 2014

2014-07-25 (F) Sous Vide Oven V2.0


he cord-tite connector was installed using an electrical locknut left over from the first sous vide oven build. A heavy-duty power cord was tightened into the cord-tite connector. The wire sheathing was removed from the first six inches and the wires were stripped. Only the common - white wire - and the hot - black wire - were inserted into lever-style wire nuts, also left over from the first build. On the duplex receptacle the metal tab between the two hot terminals - brass bolts - was removed.


Heavy duty cord installed

Wires stripped and inserted into lever-style wire nuts

Tab removed from duplex receptacle
Wiring of duplex receptacle. Ground wire not show


Wires for the temperature probe were soldered to the screw terminal strip which was installed using four #10-32 bolts from a box of skateboard parts. All wiring done to the receptacle was done while the receptacle was free of the enclosure lid. All wiring to the temperature controller was done while installed on the enclosure lid. When all components were installed on the faceplate the receptacle cover was installed.

Solder, wires, and screw terminal for temperature probe
Wires soldered to screw terminal
Holding the screw terminal with a clipboard. I highly recommend
Enclosure lid components installed

While looking at the design it seemed that a DC power supply would be necessary for running the SSR. The rest of the wiring was completed so a DC supply may be installed with minimal new wiring.

 All wiring expect for DC supply

Faceplate finished
Unit mostly assembled but the plug is taped with a warning message

To do:
  • Sketch schematic 
  • Find and install DC power supply 
  • Mount internal components 
  • Seal thermometer + Install 
  • Program 
  • Test

Journal page


The rest of the posts for this project have been arranged by date.

A list showing of all the final posts of COMPLETED projects.


This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

Friday, July 25, 2014

2014-07-24 (Th) Sous Vide Oven V2.0



Construction on a second sous vide oven controller began in order to gift one to my mother who expressed interest. The second version uses a different temperature controller which utilizes a PID loop and a solid state relay (SSR). The change in controller was prompted by advice from Instructable comments of the first build. The enclosure, receptacle cover, receptacle, and cord-tite connector purchased were the same as the first build. The components were arranged on the enclosure faceplate to establish the arrangement. Masking tape was applied in the vicinity of the devices before each device was carefully aligned and arranged using an artist’s square.

Loose arrange of devices

 Masking tape where the devices will go

Using an artist's square to align the components

The hole positions were marked on the masking tape. 11/64” holes were drilled at the corners of the controller hole and for the temperature probe terminals. Large diameter holes were drilled for the receptacle which fit the receptacle but did not provide enough clearance to add the receptacle cover. The rectangular hole was cut out with a handheld jigsaw and repeatedly trimmed until the receptacle fit squarely. The cutting was all done on the underside of the enclosure faceplate to avoid scratching the visible surface.

 Marked off places to make holes

11/64" drill bit used to drill holes for the corners of the temperature controller
Round holes for area of receptacle
Rectangular hole for receptacle

The hole for the controller was drilled with a large diameter bit to so the edges of the hole aligned with the edges of the intended square hole. The first two cuts left a heart-shaped hole in the PVC faceplate. The hole was slowly trimmed until the controller fit squarely. Holes for the mounting probe terminals were drilled in one side of the enclosure to plate the cord-tite connector.


 Large holes drilled for temperature controller hole

Heart-shaped results of cutting

 Devices and their mounting holes


Cord-tite connector mounted in box

To do:
  • Wire components
  • Mount components
  • Test controller

 Journal page 1

Journal page 2



The rest of the posts for this project have been arranged by date.

A list showing of all the final posts of COMPLETED projects.


This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.