Hi all and thank you in advance for your help.
I have a problem with my GF cats scratching at the door before we get up in the morning so I had the idea of making a motion controlled squirt gun that would squirt them when they come near the door, a bonus would be using it to keep them off the counters as well.
I was hoping to use a motion controlled light I already had and I purchased a squirt gun with a motorized trigger. (Light http://www.amazon.com/gp/product/B00GWLVREE/ref=oh_details_o05_s00_i01?ie=UTF8&psc=1 Squirt Gun http://www.amazon.com/gp/product/B00416QW88/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1). I was able to isolate the output of the PIR sensor in the light but unfortunately it does not have enough to drive the motor so I tried a relay and this worked good. But the light is set to be active for 1 Min which is way to long, I would need it to be 1 -2 sec. I was thinking about using a 555 circuit to drive the relay but I was hoping to get your advise as I have a sneaking suspicion there might be an easier way.
Thank you very much!
Sean

 

There might be an adjustment for how long the light stays on, so I'd check for one of those first, but if it doesn't have one then I think it probably would come down to using a monostable 555.

using a 47K Resistor and a 10uF cap you would get a 0.5sec pulse.

I just roughed that up with an app I have on my phone.

 

Have you considered a new girlfriend?

 

hi Kucster,

This method may get the job done, bit over the top, but well worth watching.

http://www.youtube.com/watch?v=uIbkLjjlMV8

http://www.youtube.com/watch?v=goZ2DqMnaGc

 

You simply HAVE to watch this video.

 

There is most likely a chip in the PIR sensor that controls the output. Get the chip number and maybe the output time can be controlled. Can you get a closeup of the PC board?

 

Thank you everyone for your response's and what an awesome video!

@burger2227 I do not have it with me but I can find out later and let you know. I did some research on changing the timing of the circuit and most people said to change one of the R or C's. The problem I see if that they are surface mount and I'm not sure if I would be able to get them off the board and if I could I do not have any other surface mount components.

@GRNDPNDR Thank you for your help, I will use this as a start if I choose to go that direction

 

Personally, I like this device. It does what you are describing but with compressed air, thus no worries about water damage. And I can say it works well (at least while it lasted).

However, water is very effective too. A monostable 555 would do, just be sure to add an edge-trigger, otherwise the 555 will keep your water gun on as long as the PIR is outputting a signal. Take a look here. You can also find a schematic for making the monostable.

 

You simply HAVE to watch this video.

Hilarious. I still think changing the girlfriend is easier...

 

Thank you very much everyone for your help. I was able to go back an analyze the circuit closer and find the R and C combo that was setting up the timing. I replaced the R with a POT and now the timing is adjustable.

Thanks again