lanternfish
Senior Member
At my former workplace I was tasked with modifying three large smoke machines so that they could be run via DMX. These machines were originally used as part of a theft/robbery prevention system in a jewellery shop. A previous employee had attempted to DMX them but had only succeeded in dismantling them.
Each smoke machine contained two 1000W heater blocks, fluid pumps and associated optocouplers and triacs.
On the rear was a 15-pin D-type connector that provided access to 3 x optocouplers and 2 x relay contacts. (1 NC and 1 NO). This connector also provided access to (nominally) +16V DC and 0V.
The (external) DMX interface is a 3-ouput DMX relay device (minus the relay's) from dmxprojects.com with one output driving each smoke machine via the optocoupler inputs of the 15-pin D-connector.
On the PCB were two buttons (Test and Fluid Reset).
The smoke machine that was complete revealed some excellent information on voltage levels from the thermocouples and I traced out all the traces on the PCB.
As the main processor was a PIC 18C74B-04 it was a simple matter of fitting a suitably programmed 40X2 in it's place. Well almost! I first had to get rid of the Fuid Reset button as this was linked to the pins that were required for the programming pin(s) and attach suitable resitors. Once done it was all go.
The programming was fairly basic comprising of 3 loops:
1. Preheat Mode:
This simply looped through alternately heating each block to a defined level until the upper heating level was reached.
2. Quiescent Mode:
Having pre-heated the block temperatures are maintained within predefined limits.
3. Trigger Mode:
When triggered this section turns on the pumps and the heaters. Testing showed that this was important as the blocks would cool down rather quickly if heating was not maintained.
If the temperature of a block fell below a predefined threshhold then its pump is turned off until the temperature returns to the upper limit. At that point the pump is turned on again.
A relatively simple modification. In the end though I was only able to get two machines going as the third had one stuffed block and one erratic pump. Still, a satisfying project.
Each machine drinks approx. 1 litre/min of smoke juice when running continuously. When we tested them in our workshop, you could barely see your hand at arms length from your face. It takes one machine approx 10 secs to fill a medium (9m x 6m) stage.
The DMX relay kit from dmxprojects.com also has a timer mode. When set to this a DMX level below 10% is OFF and above 90% is FULL ON. Levels between 10% and 90% provide 8 timed ON/OFF modes from 1 sec ON/10 sec OFF through to 10 sec ON/120 sec OFF e.g. 45% (41-50%) is 2 secs ON/30 secs OFF.
So enjoy the video. The smoke machines are in a timed mode to save juice and it was a bit windy the day I took the video.
Each smoke machine contained two 1000W heater blocks, fluid pumps and associated optocouplers and triacs.
On the rear was a 15-pin D-type connector that provided access to 3 x optocouplers and 2 x relay contacts. (1 NC and 1 NO). This connector also provided access to (nominally) +16V DC and 0V.
The (external) DMX interface is a 3-ouput DMX relay device (minus the relay's) from dmxprojects.com with one output driving each smoke machine via the optocoupler inputs of the 15-pin D-connector.
On the PCB were two buttons (Test and Fluid Reset).
The smoke machine that was complete revealed some excellent information on voltage levels from the thermocouples and I traced out all the traces on the PCB.
As the main processor was a PIC 18C74B-04 it was a simple matter of fitting a suitably programmed 40X2 in it's place. Well almost! I first had to get rid of the Fuid Reset button as this was linked to the pins that were required for the programming pin(s) and attach suitable resitors. Once done it was all go.
The programming was fairly basic comprising of 3 loops:
1. Preheat Mode:
This simply looped through alternately heating each block to a defined level until the upper heating level was reached.
2. Quiescent Mode:
Having pre-heated the block temperatures are maintained within predefined limits.
3. Trigger Mode:
When triggered this section turns on the pumps and the heaters. Testing showed that this was important as the blocks would cool down rather quickly if heating was not maintained.
If the temperature of a block fell below a predefined threshhold then its pump is turned off until the temperature returns to the upper limit. At that point the pump is turned on again.
A relatively simple modification. In the end though I was only able to get two machines going as the third had one stuffed block and one erratic pump. Still, a satisfying project.
Each machine drinks approx. 1 litre/min of smoke juice when running continuously. When we tested them in our workshop, you could barely see your hand at arms length from your face. It takes one machine approx 10 secs to fill a medium (9m x 6m) stage.
The DMX relay kit from dmxprojects.com also has a timer mode. When set to this a DMX level below 10% is OFF and above 90% is FULL ON. Levels between 10% and 90% provide 8 timed ON/OFF modes from 1 sec ON/10 sec OFF through to 10 sec ON/120 sec OFF e.g. 45% (41-50%) is 2 secs ON/30 secs OFF.
So enjoy the video. The smoke machines are in a timed mode to save juice and it was a bit windy the day I took the video.