The PCS Scenemaster

Description: The PCS SceneMaster Model LM4LS2 was awarded "Best Web Site" by Home Automator Magazine and was installed in the spring of 1999. This controller can ramp lights on and off and create "scenes," where a single X-10 command can generate a combination of lighting levels. These levels can be achieved with programmable ramp rates. In a specific location within the home, four lighting circuits are controlled. Previously, three of these circuits were managed by standard X-10 wall switches, while the fourth was a bank of fluorescent lights that were not X-10 controlled. This location manages lighting that illuminates a significant portion of the open living space, making it an ideal choice for the SceneMaster. The intention was to control the fluorescents as well; however, connecting them directly to the TRIAC output of the SceneMaster posed risks. Therefore, a relay was added to the SceneMaster. The relay coil is connected to "Load 4," and its output links to an unused contact on the barrier strip at the back of the SceneMaster. The relay is a four-pole, double-throw type and fits within the SceneMaster housing. Three relay poles are used in parallel to share the current and provide redundancy, while the fourth pole serves as a spare contact in case the others fail. This design allows for temporary wiring to the fourth contact to maintain circuit operation until a long-term solution can be devised. Additionally, a Metal Oxide Varistor (MOV) surge suppressor is placed across the relay contacts to protect against voltage spikes. One operational limitation is that this circuit cannot be dimmed; dimming the "Load 4" circuit causes the relay to buzz loudly during the transition from bright to dark, preventing the fluorescent lights (totaling 240 Watts) from lighting. The SceneMaster lacks a built-in control pushbutton, necessitating the purchase of "slave switches" for non-X-10 control. With a need for approximately six slave switches at around $20 each, the cost could become prohibitive. Consequently, an investigation into building the slave switches was conducted. Based on the SceneMaster user manual, a schematic was developed that successfully replaced the slave switch. Testing confirmed its functionality, and it was found that a half-watt resistor could be as high as 500K, but a 100K resistor was chosen as a balanced option for operational margin and safe current limits. Round and square pushbuttons from TechAmerica Inc, priced at approximately $2 each, were selected for their compatibility with standard wall plates, allowing reuse of existing decor. The unit is mounted on the wall behind the control panel located in the garage. The large box above the PCS unit accommodates the Home Automation Computer. Modified chassis from two standard wall switches were utilized to secure the wall plate, with four of the eight screws serving a functional purpose and the other four being decorative. A grey control cable connects the switches to the SceneMaster, exiting through a hole drilled in the back of the junction box and leading into the garage where the SceneMaster is installed. Power and loads for the SceneMaster are connected via a heavy gauge cable. The entire system integrates effectively with the Home Automation System, allowing for automatic lighting control. For instance, when night falls and no lights are on downstairs, the Home Automation System activates two of the four SceneMaster circuits, illuminating a significant portion of the bottom floor.

The PCS SceneMaster Model LM4LS2 serves as a versatile lighting control solution, particularly in environments where multiple lighting circuits require coordinated operation. The ability to create scenes enhances the functionality of the lighting system, allowing users to establish specific moods or settings based on their needs. The incorporation of a relay for controlling fluorescent lights demonstrates a thoughtful approach to integrating non-X-10 compatible fixtures into a modern home automation system. The use of a MOV surge suppressor adds an additional layer of protection, ensuring the longevity and reliability of the lighting circuit. Furthermore, the DIY approach to creating slave switches not only reduces costs but also allows for customization tailored to the specific requirements of the home. Overall, the SceneMaster's design and implementation reflect a comprehensive understanding of both electrical engineering principles and practical home automation needs.The PCS SceneMaster Model LM4LS2 was won from Home Automator Magazine for `Best Web Site` and was installed during the spring of 1999. This controller is capable of ramping lights on and off, and `scenes`. This is where a single X-10 command can produce a combination of lighting levels. These light levels can be achieved with programmable ramp rat es. I have a location in my home where four lighting circuits are controlled. In the past, three of these have been controlled by standard X-10 wall switches. The fourth one was a bank of fluorescents, and it was not X-10 controlled. This location controls lighting that covers a majority of the open design of the living space, and is the logical choice for the SceneMaster. I wanted the fluorescents to be controlled also, but connecting them to the TRIAC output of the SceneMaster is risky.

I therefore chose to add a relay to the SceneMaster. The coil is wired to `Load 4`, and its output is connected to the unused contact on the barrier strip on the back of the SceneMaster. The relay is a four pole, double throw, and fits inside the SceneMaster. The whole package is quite tidy and self-contained. Three poles of the relay are used in parallel to share the current and to provide redundant contacts.

The fourth one is left for a spare contact in case the other three fail. If that point comes I can then temporarily wire to the fourth one to get the circuit operational again, buying me some time to think up a long term solution. In addition to three poles sharing the current, I added an MOV (Metal Oxide Varistor) surge suppressor across the relay contacts.

One operational restraint is that this circuit is not allowed to be dimmed. When the `Load 4` circuit is dimmed, the relay buzzes loudly in the transition range between bright and dark. When this occurs, the fluorescent lights (240 Watts in all) do not light. Time will tell if this is an issue. Unlike standard X-10 wall switches, the SceneMaster does not have a control pushbutton built into it.

In order to have non X-10 control, one needs to purchase `slave switches`. Since I needed about six of these at a cost of about $20 each, I realize that non X-10 control could get expensive. For that reason I investigated building the slave switches myself. Based on the user manual of the Scenemaster I speculated the following schematic could be used instead of the slave switch.

Testing showed that this circuit does indeed work. I found that the half watt resistor could be as high as 500K, but I decided that 100K provided a good compromise between operational margin and a safe current limit. The buttons used were round and square pushbuttons from TechAmerica Inc for about $2 each. Apart from their low cost, these switches were chosen because they fit into the hole of a standard wall plate.

I could then reuse the existing wall plates, which already match the decor of the home. The actual unit mounts on the wall behind the control panel, which happens to be the garage of my home. The large box above the PCS unit is the alcove that houses my Home Automation Computer. The modified chassis from two standard wall switches were used to hold the wall plate. Four of the eight screws on the front of the wall plate thus hold the plate to the wall, the other four are decorative.

The grey control cable connects the switches to the SceneMaster by exiting thru a hole drilled at the back of the junction box. This cable then leads into the garage where the SceneMaster is mounted. The loads and power to the SceneMaster is connected via another (heavy gauge) cable. The whole system works quite well together with my Home Automation System. For example, when it is night time, and no lights downstairs are on, the Home Automation System turns on two of the four SceneMaster circuits, lighting a good portion of the bottom floor of my home.

When I descend the stairs from the second floor, the lighting cascades ge