Initial Idea

As I built my lighting system for my DJ setup I knew I needed a way to control my old PAR Flood Light chaser which is sound activated but not DMX enabled. I wanted a way to cut the chaser in and out automatically with my lighting scenes. For this I used a DMX 8ch relay module which I initially used to simply control a 240v high powered relay switch to turn power to the chaser on and off.

I had a smoke machine that was controlled by a small wireless remote or from the button on my light mixer and bubble machines which needed to be switched manually on and off. After a few gigs I learned I really needed a timer on my smoke machine and I needed a way to control the bubbles easier possibly also with a timer and I really wanted wireless control of the bubble machines too so I started designing all these requirements into a single multi-function controller. 

I started by making a list of what I wanted the system to do:

- 3 devices I needed to control (Light Chaser, Smoke machine and Bubble machine)
- Allowance for additional devices such as snow machines or other effects down the track
- The ability to have DMX control any device
- 2 independent timers with both adjustable on/off times
- Ability to assign either timer to any device
- Wireless on/off operation of any device
- Manual control of any device
- Ability to enable/disable DMX/Wireless/Timer for any device
- Visual feedback of what is triggering a device (DMX/Wireless/Timer)
- 12v to be triggered out a jack to connect to remote power switches.

Basically the controller would be powered from a 12v plug pack and allow timers, DMX signals or wireless remote to trigger a device by sending 12vDC out the controller channel which can then operate a high powered relay switch to switch 240v to a device or a dry contact relay switch such as required by the smoke machine.  

I started my initial design based on 8 channels of control but decided to settle for 6 channels of control because of the space needed for all the switches and I do not believe I would ever need more than 6. The parts list was roughly drawn up so I could research what parts were available:

- DMX relay module 
- Radio Relay Module
- 2 x Timer Module (with adjustable on and off times)
- Toggle Switches (on-off-on)
- 3mm LED with bezel
- 2.1mm DC sockets
- 1 XLR male panel mount
- 1 XLR female panel mount
- IN4004 Diodes (approx 20)

Getting The Parts

I already had the DMX relay module so I just needed the wireless module and the timers. All other components (switches/leds/plugs etc) were sourced at my local electronics store (Jaycar) as these were common parts. 

First was the wireless module as that was the easiest.  

Ebay listed quite a few wireless relay modules that are all based around the same kinds of 433Mhz receivers and transmitters. I have used these types before and they work pretty well for this kind of task.

This module would be installed in the controller and connected to each of the channels to operate from the remote. 

Next were the timer modules. I needed a specific kind of timer module that allowed 2 different timers to be set (relay ON time and relay OFF time). I purchased a few different cheaper PCB style timers with led readouts to test operation and see how they would work. They were exactly what I needed but being only small PCB timers they would be painful to mount in a case with the other switches.

I hunted around for panel mount timers and found the one pictured. It offered 2 different timers and had several modes of operation. Importantly it was designed to be flush mounted in a panel and was simple to program and operate. These were just $10 from Ebay (here)

Designing The Circuit

With parts on order I could now start designing exactly how I wanted the system to operate. I have a lot of experience with designing systems and working through logical solutions and started as I always do of thinking out the problem and writing down how it would operate:

- Power switch to turn on the system
- Master switch to enable/disable the timers
- Master switch to enable/disable DMX control
- Master switch to enable/disable wireless control
- Selection switch per channel to select timer 1 / 2 / No Timer
- Selection switch to select DMX On/Off
- Manual channel control on/off switch
- Wireless control in paralell with all other controls
- LED indicators showing channel/dmx/wireless/timer status for each channel

From there it was time to draw up a diagram and figure out how it would all work. To do this I use an online service http://www.schematics.com which allows for quick and easy schematic blueprints. This took a little time to figure out and get down but the final schematic was as follows:

Designing The Controller Layout

Once I had the schematic planned out I then started to design the control box. I needed to make sure everything would fit and I needed a box that could be placed into a rack and operated from the front. 

The housing I decided to use was a common one I have used a number of times before for mounting instrumentation and controls in. It's available from Jaycar and was 253x190x82mm. I wanted the controller to be desktop and also be mountable in my rack housing so it was the perfect option. The issue was it did not have enough space for all the controls for an 8ch system which is why I decided on 6 channels.

With a circuit designed and a housing picked I needed to design the panel layout and make sure things would actually fit physically not just roughly on paper. For this I used Sketchup

I measured the size of every component and of the housing itself and designed each component in sketchup. Luckily for the switches I found existing models but I needed to mock up the housing panel, box, timers and LEDs. I shifted things round a bit until I found a layout that would fit everything and not be too crowded:

Up the top are the 2 timers. Each one can be set to a channel using the T1/T2 switches to the right. These are centre OFF which sets neither timer to the channel. Below are the main power switch and master switches to deactivate the timers, DMX and Wireless modules separately. On the right in the middle are rows of LED indicators that show when the channel is active and if DMX or Wireless is active for the channel. On the far right is a 3 position switch to set the channel to be triggered from DMX (left) completely off (center) or manually ON (right). 

Once I was happy with the layout I designed a template I would use to drill out the holes and cut the mounting holes for the timers

Building Controller

With the template stuck on the front panel (made from acrylic) I used a nail to punch each location where a hole needed to be drilled for the switches and LEDs. I then used a small 4mm drill to tap a pilot hole before using the 6mm drill to drill out the holes completely. 

Next I drilled a hole in each corner for the timers and used a coping saw to cut out the holes. After each hole was cut I used a rotary tool to smooth and nibble the edges until the timer fit perfectly. 

I mounted everything into the panel for a test fit and ran into a problem. I decided to order in special switches for my power and master switches that had an LED built-in but these were much larger than the toggle switches I used in the 3D design. While there was just enough room to fit these under the timers the bottom of the switches touched the bottom of the case and prevented the panel to mount properly in the case by just a few milimeters. This was a frustrating setback but was solved by grinding down some of the inside plastic to make enough room... everyone needs a multi-tool!

For the LEDs I decided to order pre-wired 12v 3mm LEDs from an electronics supplier through ebay who had different colour packs. This saved me a lot of extra time having the dropping resistor pre-soldered and each LED came with a bezel. I decided to hot glue all these once fitted to stop any popping out  

 I then setup my work station in front of my computer, threw on some youtube documentaries and set about wiring everything in together

Finished!

The finished controller worked perfectly and exactly as I designed which is always a good end game. I already had small 1m extension cables with inline 12v relay switches I had made for other projects which I used with this controller. Around the back of this is a 12v DC input (2.1mm DC socket), 6 x 12v switched outputs (2.1mm DC sockets) and XLR in/out for DMX. 

Having the timers available for controlling bubbles and smoke worked out to be very much needed allowing a constant smoke filled room making the light show really stand out. No more flooding the room for 30 seconnds every 10 minutes. 

The total build cost was approx $100 for all components with most of the cost in the toggle switches. I could have tried to save a few dollars here but have been burned on cheap switches before so stuck with quality proven ones. 

Feel free to ask any questions if you like.