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How do I wire a fog machine to be triggered by a motion sensor?

I have a couple fog machines purchased at Target around Halloween last year. The model has a switch on an extension cord which when pressed triggers the fog machine to produce fog for 5-10 seconds. They work great but I want to use a remotely placed motion sensor, like from a motion sensor flood light to trigger the fog machine when people walk past. I purchased a replacement motion sensor module for a flood light and looked at the wiring of the switch and the fog machine but haven't figured out how to properly wire it. The motion sensor module has a "test" setting which would turn on the light fixture for 5 seconds, I want to use this to trigger the fog periodically as people walk past. Any help would be appreciated. A couple photos to show the pieces are included. If more detailed information about the wiring is needed please let me know.

jj.inc3 years ago
 If your fog machine is like mine it has a detachable trigger w/ a light and the socket for it looks like one on a computer cord.  The easiest thing to do would be to find a cheap motion sensor w/ a little dinger on it.  Then replace the speaker with the switch on your regular remote.
I don't actually have these labeled with the correct prong-poles but this gives you an idea
Motion Sensor fog machine.png
seandogue4 years ago
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cbulloch (author)  seandogue4 years ago
Thanks for the response. My circuitry skills are generally pretty basic,I wire a basic light & switch circuit in my house but when itcomes to relays, transitors, and the like I don't have muchknowledge or experience.

Not sure how I can tell if the sensor has an isolated output relayor if I need to add one. Can you give me a little advice on how to goabout it? I appreciate the offer for help.
(removed by author or community request)
(removed by author or community request)
cbulloch (author)  seandogue4 years ago
I think I have the motion sensor figured out. I wired it in a simple circuit with a lamp and an extension cord. I now can see how it works to operate the light. Still didn't get into the guts of it, and not sure if I need to. (Fig 1)

I now moved on to the fog machine switch to understand how best to connect the motion sensor to act as the switch. I did some investigation with a multimeter to get a sense of what is happening. I am a bit confused and need some help (again).

The fog machine switch has a small lamp and a toggle switch. When the fog machine is first plugged in, it has to warm up before the switch will activate the fog. During this startup time (cold) the lamp is on. When the machine is warm and ready the lamp turns off. If the fog is run for a length of time say 15s it seems to have a safety mechanism to let it cool down to normal operating temperature. When it is "hot" and in the wait mode the lamp is on again. 

In each of these periods I documented the voltage across the various parts of the switch to try to understand what is happening. The results are shown in Fig 2.

I am confused as how to replace the switch. Any pointers on how to proceed? Are there any other data points that would be helpful to know?


MotionSesorWiring.pngFogMachineSwitch.png
cbulloch (author)  seandogue4 years ago
I think I am starting to understand. I'll take a look at thesensor in more detail tomorrow to see what I am working with. The usermanual for the sensor can be found here.http://heath-zenith.hcents.com/data/manuals/598-1295-02.pdf I alsoattached a crude mock up of the same diagram.<br /><br />The basic connection diagram which from my elementary understanding ofyour response and diagram, would seem to have a relay involved. Iimagine that if I can just get the connections to the switch on thefog machine correct it should work. I get into it and do some testslike you outline and let you know what I find.<br /><br />
lofty4 years ago
We did this last year for halloween but I made a laser gate instead. You should take the button apart that controls the fog machine and wire a relay to the 2 contacts of the button. I don't know how those sensors work but you should check the manual for the connections and measure the voltage that it outputs. If it's not the right voltage for your relay you might need to use a transistor to control the relay. Heres how we did it anyways.... For the laser gate it was just a cheapo laser pointer with the button taped down aimed at a light dependant resistor. Put the LDR in a voltage divider with another resistor, then take the midpoint into a comparator op-amp, then make that trigger a monostable a 555 timer which will control the relay.
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