 |
16-position ActiveKnob Station and
AC power junction box (beneath)
Before adding With Cover and temporary
panel cover (ugly) knobs
A single removable wall-colored panel covers both the the ActiveKnob (low-voltage) Station and the 120vac junction box. Note that the fact that the low-voltage and 120vac boxes are close together is an artifact of the fact that the installation is a retrofit. There is no electrical connection whatever between them.
The portion of the panel in front of the ActiveKnob station box is covered with wood veneer. The black plastic knobs are temporary until wooden knobs are made from the principal wood types used in the den, dining room and kitchen (oak, walnut and hickory respectively) and installed.
The bottom 12 knobs individually control the 10 ceiling lights and two fans in the adjacent kitchen, dining room, and family room.
individually control the 10 ceiling lights and two fans in the adjacent kitchen, dining room, and family room.
ActiveKnob (a 10Kohm Alps motorized potentiometer $3.50 from www.allelectronics.com )
Photo showing back side of the ActiveKnob. I soldered in a diode bridge to power the LED that is located in the shaft. Whenever the knob is being controlled remotely (i.e., the motor is turning) , the LED light can be seen through a small hole in the front of the knob.
Plan is replace the uppermost rotary potentiometer with a Panasonic EVANMKP08B14 motorized slide pot with 4” travel to distinguish it functionally from the lighting controls and to allow for clearer labeling as an occupancy indicator/input (Goodnight, Just-Back-from -Work, Vacation, etc)
The middle set of three knobs each will control the group of four ActiveKnobs directly below them simultaneously through software. This provides for being able to set scenes for each group of lights or have them work in concert.
There is room reserved on the upper left of the panel to mount a LCD+ from Basicx for enunciation and local analog measurement and control. The LCD+ is a RS-232 interface, four-line x 20-character backlit LCD with eight,10-bit analog inputs, eight digital output/relay drivers, and 4x4 keyboard input..
Inside
of 16-position ActiveKnob station panel
The motorized potentiometers used (Alps Electric# 726T-10KBX2) are 10K ohms. .The output is buffered by inexpensive unity-gain LM324 quad operational amps. The divider voltage is derived from a buffered 10.0vdc reference (LM4040-10). High accuracy signals simplify calibration for (eg) dimmer curves in software. Buffering reduces the likelihood that a problem in one signal will affect them all. The standard for analog 0-10vdc lighting control (ESTA ANSI E1.3 -2001) stipulates 10K ohms input impedance.
Electronic controls for the motors (description in starts in paragraph below) are presently located in the basement. But they could be relocated to this enclosure which would reduce the low-voltage wiring requirement to a single RS232 cable between the station and the basement panel/controller.
The lights could be quickly converted to on-off (no dimming) using minimal (no) electronics simply by connecting the outputs of the pots directly to the input of the Solid State Relays (SSR’s). This would not intrinsically affect automation. See Modes
16/32-channel ActiveKnob Motor Control Circuit Board
The circuit is controlled by a Netmedia BX-24p (purchase here: www.phanderson.com) with conditioned 0-10vdc analog inputs and Microchip TC4423 motor driver IC's
An unstuffed 16/32 ActiveKnob prototype is shown above. Click picture to enlarge. Parts (less PCB) are about $70 for 16 channels and less than $100 for 32 channels.
A 3.9 x 6-inch (euro-board) printed circuit board layout is shown above. It uses different H-driver, multiplexer and latch IC's and has surface-mounted IC's on both the top (red) and bottom (blue) of the board
It provides for:
 | 16 inputs (0-10vdc) from ActiveKnobs
|
|
Motor control for 16 channels of ActiveKnob
| ||||||
| Eight additional 0-10vdc analog inputs with 10-bit resolution
| ||||||
|
Header for TTL connection to a 16-input multiplexor and analog-to-digital converter with 16-bit resolution (Microchip TC3400) that can be used for sensors that require high resolution such as thermocouples and thermistors. | ||||||
|
A half-euro 3.9 x 3-inch board layout for an optically-coupled 16-input differential input board is shown below and discussed in the environmental monitoring section of this web site. |
|
4 com ports including two RS-232, one
RS-485 and one TTL-level.
| ||||||||
|
Real-time clock/calendar with a high-accuracy DS32kHz oscillator (on daughter board). This eliminates the need to synchronize the on-board clock more often than about once every year. |
|
32+ MB of static memory on a Rogue Robotics uMMC SD daughter board This allows for logging of all functions at one minute intervals for a year before downloading is required. |
Description and objectives of ActiveKnob "Mode Four"
This controller is designed to implement the configuration that I've termed "Mode 4" here on this site. The 0-10vdc signals from ActiveKnobs are connected both to the device to be controlled (AC or DC lighting dimmer, preamp/audio matrix etc) and to the motor control circuit board described here. So the device output is always controlled by the physical position of the potentiometer knobs.
Automation is accomplished when the controller board is instructed via RS-232/485 to rotate a motor attached to the potentiometer clockwise ("up", "higher" ) or counterclockwise ("down", lower"), much like the volume control on a modern receiver can be controlled by hand (literally) or by IR remote.
The automation system knows when to stop turning the motor because the BX-24 constantly monitors the potentiometer output (control ) voltage. This voltage can also be logged to maintain a historical record of status. or monitored to provide controller defined flag, "wake-up" or alarm functions.
Mode
4 is described here. In brief, it provides provides:
|
That the actual physical position of the
knob always accurately indicates the value of the device being controlled | ||||||||
|
Robust fail-over modes. If a computer or
other home automation controller goes off-line or fails, manual operation of
the system is unaffected. | ||||||||
|
Simple reversion to a conventional
standardized system. Removing the custom controller(s) causes the system to
conform to industry standard
0-10vdc control. | ||||||||
|
Use of ActiveKnobs for control of
devices with native
| ||||||||
|
Use of ActiveKnob as logical devices
defined by the home automation system such as:
|
