# Motion activated and Interval timer



## Fester (Sep 17, 2006)

I have an old LiteFX 700w fogger that I am wanting to use with a hacked motion activated security light. Last year I was able to get the motion sensor to activate the fogger via the remote, but I want to try and incorporate a 555 interval timer to try and control the length of the blast as well as prevent premature re-triggering.

My 555 interval timer has a limit of 24v/3A. I need a relay that will be able to be controlled by the 555 timer and handle 120v/1A.

My thought is to have the motion sensor trigger the 555 and then the 555 control of relay. Does this sound valid? I used the tutorial that shows how to isolate the motion sensor relay from the 120v power of the sensor so I think that I can use it to switch the 12v power for the 555 timer, but I'm not sure about what relay to use. I was looking at this one 
http://www.simplecircuitboards.com/1A Relays.html

I am headed in the right direction?


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## Otaku (Dec 3, 2004)

The board in your link is a TTL-driven circuit. TTL signals are for transistors to talk to each other, so it probably won't work in this application.
The biggest problem with trying to get fog on demand is that you don't know when the fogger is going to go into re-heat mode. Even a fogger that is just sitting idle will eventually cool down and need to re-heat so your system may try to demand fog that isn't available. The Lite F/X 1741 (is that your fogger?) isn't a continuous one, so it will cycle off now and then.
I'd suggest getting one the 1200W continuous foggers to do this trick. That way, the fogger is always ready to go.

As regards the timer board, use the Time Delay Relay Board on this page:
http://www.simplecircuitboards.com/Timer Boards.html

This board uses a fixed resistor to set the "on" time, but you can substitute a 100K potentiometer so that you can adjust the time without having to change a resistor. It will deliver an "on" time just once when triggered, then wait for the next trigger event. The trigger must be "dry" i.e. no voltage, so you need to use a 110VAC relay that is activated by your hacked motion detector. The Common and Normally Open terminals of that relay will be wired to the Trigger input of the timer board, which needs it's own 12VDC power supply. Using the motion detector to control 12VDC power to a 555 circuit to act as the triggering event will result in failed 555 IC's and unreliable performance from the circuit. Don't ask me how I know this...LOL. This still won't solve your basic problem, however, which is fog on demand. Let me know if I can help.


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## fritz42_male (May 5, 2009)

If you search the forum for '$10 prop controller', I modified a picaxe board setup I have to act as a variable delay/duration timer for my fogger. I had to do this because I couldn't get a timer in Australia for under $100

Total cost was about $25

The same setup could easily have a PIR linked in to provide motion activated fog and I'm just playing with cheap PIR sensors at the moment. I'm using this one:

http://www.futurlec.com/PIR_Module.shtml

However Otaku is right about the cycling - not sure of an easy way to get round this but maybe adjust whatever setup you have to prevent retriggering within a set period. Easy enough with a picaxe setup.


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## Atom058 (Sep 20, 2009)

Fester - I came across your post and see that you were considering a board that I make (simplecircuitboards.com) and I just wanted to let you know that I have been presented with this problem by several people looking for a easy solution. I built a new board just for this purpose that took in everyone's concerns and wishes. I do not have this on my web site yet (I'm very far behind on my updates!), but here is an excerpt from my cut sheet on the board:
"This board has 3 adjustable timing periods that, when triggered by either a dry contact closure or by a PIR, will delay activation of a prop, activate the prop and then prevent the prop from being activated again unit the subject has left. It also has built-in suppression for switching "noisy" devices."

I think it will do exactly what you want. If you want more info, please just email me - [email protected]. Thanks! Jeff


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## hpropman (Jul 27, 2008)

As far as telling if the fogger is ready for fog does a light come on to indicate that the fogger is ready why can't we just have that (depending on the voltage) trigger a 555 or the picaxe controller. You can also use a LDR (light dependent resistor) circuit to indicate to the chip that the fogger is ready


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## Fester (Sep 17, 2006)

Thanks for the feedback. I wimped out and decided to just by a bigger fogger with a timer and just set it for a short interveral/short duration. I won't be fog on demand, but should still get pretty close to getting what I am looking for. It will just be firing when nobody is around to see


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## Otaku (Dec 3, 2004)

hpropman said:


> As far as telling if the fogger is ready for fog does a light come on to indicate that the fogger is ready why can't we just have that (depending on the voltage) trigger a 555 or the picaxe controller. You can also use a LDR (light dependent resistor) circuit to indicate to the chip that the fogger is ready


Your suggestion of a CdS diode to pick up the "ready" LED got me thinking that you could use the power going to the LED as the base/gate voltage to switch a Darlington, other NPN, or a MOSFET. Use the transistor to complete the connection from pin 3 (output) of the 555 to a relay. That relay would switch the fog button contacts. As long as the LED is on, the one-shot timer (set to the desired fog time length) can be used to turn on the fogger. When the LED is off the 555 can still be triggered, but the output voltage stops at the transistor. With this circuit, the fogger can only be turned on when it's ready to fog. You could use a PIR or device of your choice to trigger the 555.
This design assumes that the light in the fogger button is an LED and not a low-voltage AC lamp.
One issue, though - just last night I saw a fogger manual switch that turned on the LED when the fogger was heating, and when the fogger was ready, the LED turned off. This circuit won't work for that situation. The fogger was an old Lite F/X 1741 700W machine.


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## hpropman (Jul 27, 2008)

Why can't you just use an LDR connected to the base of the transistor to trigger the 555. so it does not matter what the light is we are only measuring the amount of light that hits the LDR. This is almost the exact circuit (left half) just replace the relay with the 555 timer or controller chip.

http://www.instructables.com/id/S2YPZ3PFQ6EF21Z/

You can insert the light and the LDR in a tube to prevent false triggering.


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## Otaku (Dec 3, 2004)

hpropman,
You're correct - the LDR would work in either case (light on = ready or light off = ready). Just wire the circuit appropriately. Damn, now I'll have to build one...LOL


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## halstaff (Nov 18, 2009)

Otaku said:


> hpropman,
> You're correct - the LDR would work in either case (light on = ready or light off = ready). Just wire the circuit appropriately. Damn, now I'll have to build one...LOL


Did you ever get around to building this? I think I need at least one of these too!


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## Otaku (Dec 3, 2004)

halstaff said:


> Did you ever get around to building this? I think I need at least one of these too!


No, I never did get to it. The Pumpkin Insert stole all my time...lol


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## halstaff (Nov 18, 2009)

Sorry about that! My fault.


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## Otaku (Dec 3, 2004)

halstaff said:


> Sorry about that! My fault.


Not at all! I've been working on that project for several weeks ($20 Prop entry). I plan to get back to this project as soon as I finish up a couple more things.


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## halstaff (Nov 18, 2009)

I'm just finishing up the second board, just a couple of things left to do. It will have to wait until tomorrow as I need to go get ready for tomorrows bike ride now.
Always plenty of projects to do. My wife was telling a new coworker today what we were up to and her reply was "It's only February". My wife's perfect response was "But there's so much to do yet".


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## fritz42_male (May 5, 2009)

It's February already? Arrrrgggghhhh!


Speed up, speed up!


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