Thursday, December 18, 2008
Below are a few progress photos to give an idea of where the project is to date. All of the components that I will be installing internal to Silvia, have been installed. Those that will remain external, in an attached project box, have not yet been installed. In the next week of so, I plan to make my own project box, since I haven't been able to locate a box to purchase that is the size that I want to use.
The photos show some of the individual components prior to installation, the last photo illustrates the installation.
This image demonstrates the installation of the Solid State Relay (power supply to the boiler heating element) in the "usual" location, i.e., behind the lower front panel. The RED 5v supply wire is the PWM control from Arduino. The GREEN wire is connected to a common Arduino ground. The PURPLE wires out are the power supply to the heating element.
Here the small printed circuit board that I made to organize the QT113 capacitance sensor that is used for water level detection, the Css reference capacitors, the 5v and ground supply, the input from the sensor electrode, and the output to Arduino. The board is attached to the stainless steel wall that separates the boiler compartment from the water tank / pump area inside Silvia. The PCB is screwed into nylon bushings that are glued to the stainless steel wall with the same 5200 Marine Adhesive.
This is how it all goes together as it will be installed
Now lets take a look at the IAC5 Optoisolators....
The four IAC5 optoisolators are installed on the PB4 data board which allows for really nice connectivity and organization. On the Control Side, each individual optoisolator is connected to one of Silvia's face panel switches (power, brew, steam, hot water). The Data Side outputs 5 vdc when each of the corresponding face panel switches are "off" and 0 vdc when the corresponding switch is "on". This way Arduino can "sense" the status of Silvia's face panel buttons.
This is how I installed the PB4 with the optoisolators. The PB4 is standing on an edge, you can see a white strip to the left of the numbers on the PB4; this strip is a piece of synthetic "asbestos" to act as a bit of a thermal insulator. There is another piece of this thermal insulator that I placed over the shaft of the steam valve too.
Here is a close up of the LM34AH temperature sensor. I made a small bracket out of a section of a wall of 1" copper tubing. It is shaped so that it's ID is just slightly bigger than the OD of the LM34AH. It holds the LM34 tightly against the boiler. You can see a bit of thermal conducting grease between the boiler and the temperature sensor.
Another view of the same thing. The LM34 is held down by one of the pressurestat screws (steam)
Ok... so this is the last photo for now... It shows how I managed to pack all of the components in the photos above into Silvia:
The legend to the numbers is as follows:
1. LM34AH IC Temperature Sensor
2. IA5c Optoisolators installed on the PB4 Data Board
3. Water Level Sensor - QT113 on the homemade pcb attached to the stainless steel dividing wall
4. Water Tank - water level prob is on the front outside surface of the tank but not visible in this view
5. Hard shell, split tube thermal insulator covering the tube connecting to the steam valve
6. Woven PPS Nomex thermal insulator for a few of the wires close to the boiler.
That's where I am to date... I just got the chrome goose neck that will attach the project box to Silvia. The project box will hold Arduino, the LCD, the Real Time Clock (RTC) module, and the input device (either the Wii nunchuck, or the button interface I am currently working on). Also, I didn't take a picture of it, but the 12vdc transformer that supplies Arduino has been "spliced" into Silvia's main power supply, and is located behind the stainless steel dividing wall, underneath the water tank, next to the ULKA pump.
More to follow, once the project is completed.........