Perplexing Problem

Eagle Eye

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I've been trying to find a simple way to trigger JoeD's timer with a X10 sensor. I thought this would be great because both would work off the same battery and last a long time too boot. Plus you could change out the chip for different timing modes.
Hamiltoe has helped me on this but I figured I quit buggin him and bugg everybody else.
Heres what I know, The X10 sends a positive pulse of about 2v when motion is sensed. JoeD's timer takes a negative pulse to trigger. I tried using a comparator which works the first time the sensor is triggered, but after the timer  times out it will retrigger itself .
Figuring this is caused because the comparator keeps a positive charge on the timer trigger until it goes low.
So lets here your suggestions on how I can get these two to work together. Maps, drawings and diagrams are all welcome.
Incidently my test X10 is still going strong after a little over three months on the same two AA batterys.
 



Brian

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Have you tried using an inverting switch with a 2n3904.

You can use the 2 volt signal to turn on the transistor and at the collector with an appropriate resistor it will give you a negative going pulse.  As long as your signal from your X10 is not high to long it would be power effecient as well.

Brian
 

Tinhorn

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Eagle Eye

Tech Talk:
Some chips require only a momentary (in this case, low) pulse to trigger it.  The timer won't reset until the incoming trigger pulse is gone.  (so as long as the trigger is present, the timer won't time out)  I don't know if JoeD's is one like that or not but the following cirucuit should work either way.

This circuit is expanding on Brian's idea of the tranisistor inverter.  The capacitor will only let a negative going pulse get thru which will trigger JoeD's timer.  

Those two 47K resistors connected to "Neg Trig Out" will hold JoeD's trigger terminal to 1/2 batt volts.  If 1/2 batt volts is too low and JoeD's timer triggers, then the bottom 47K, connected to batt (-) can be increased, which will increase the "Idle" volts to "Neg Trig Out".  The problem is, if that Idle Volts in too high, the neg pulse from the cap mite not be strong enough to trigger the timer.....

****************************************

If you don't think a "Momentary" neg trigger pulse is required, connect JoeD's Trigger Terminal directly to the collector of the transistor and leave out the cap and those two 47K resistors attached to it on the rite of the diagram.
End Tech Talk

Tinhorn

 

Eagle Eye

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Thanks guys, I'll get the stuff on my way to work today and see if I can get this sucker working tomorrow. I"ll keep you updated.
 

Brian

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Tinhorn,

Thanks for the pic.  I didn't have a way to post the picture easy but that is exactly what I was referring too with some slight mods.

Brian
 

Eagle Eye

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Well I wont be able to get the transistor till tomorrow, Radio Shack doesnt stock them.
But I did do some research on JoeD's timer and found that as long as the trigger has a negative on it will not retrigger.
Example, If the timer is set for one minute, and you hold the negative to the trigger for one and a half minutes, it will not retrigger after one minute. But will trigger when you remove the negative.
Intermittant pulses do not affect the timing process.
 

hamiltoe

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Eagle Eye,
I was wondering if you ever got JoeD's stuff to work with the X10 stuff....
 

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