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TTP223 capacitance sensor rat trap for outdoor use?

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BlackICE:
Would using a capacitance sensor outdoors where it is exposed to possible fog but not direct rain be going down a rat hole?

I'm currently using a IR emitter receiver pair as a trigger controlled by and Arduino that activates a relay to trigger a modified snap trap. This works very well but has a few downside. The MCU is sleeping over 99% of the time waking up 50 times /sec, activating the IR pair and triggering if necessary. The average current draw is less than 0.4ma. Now that I have a 3d printer I would like to make a "better mouse/rat trap." The current design is larger than needed, moderately hard to set and the BOM of Arduino mini, 12v tool battery is "expensive" for mass use and if used outdoor kills too many birds.

I would like to lower the cost and power use by eliminated the use of a MCU. Both passive IR motion and capacitance sensors use less than 50ua so leaving them on all the time wouldn't matter. Adding a light sensor to trigger only during night would minimize or eliminate killing birds. The possible advantage of the capacitance sensor is the trigger's head placement would be more exact and birds would be less likely to even activate the trigger. I'm assuming a bird's pointed beak will have much less capacitance than a rat's head. Downsides of the capacitance sensor I believe is reduced reliability. False triggers would be a big negative!

Would a capacitance sensor even work or would it be going down a rat hole?

MrAl:

--- Quote from: BlackICE on September 29, 2022, 06:53:59 am ---Would using a capacitance sensor outdoors where it is exposed to possible fog but not direct rain be going down a rat hole?

I'm currently using a IR emitter receiver pair as a trigger controlled by and Arduino that activates a relay to trigger a modified snap trap. This works very well but has a few downside. The MCU is sleeping over 99% of the time waking up 50 times /sec, activating the IR pair and triggering if necessary. The average current draw is less than 0.4ma. Now that I have a 3d printer I would like to make a "better mouse/rat trap." The current design is larger than needed, moderately hard to set and the BOM of Arduino mini, 12v tool battery is "expensive" for mass use and if used outdoor kills too many birds.

I would like to lower the cost and power use by eliminated the use of a MCU. Both passive IR motion and capacitance sensors use less than 50ua so leaving them on all the time wouldn't matter. Adding a light sensor to trigger only during night would minimize or eliminate killing birds. The possible advantage of the capacitance sensor is the trigger's head placement would be more exact and birds would be less likely to even activate the trigger. I'm assuming a bird's pointed beak will have much less capacitance than a rat's head. Downsides of the capacitance sensor I believe is reduced reliability. False triggers would be a big negative!

Would a capacitance sensor even work or would it be going down a rat hole?

--- End quote ---

Hi,

I guess this is part of the "Build a better mousetrap" global project :-)

A simpler way is to use a relay contact switch, a solenoid, an inverted shoe box or similar, and a plastic  CD case that has hinges.
The rodent steps on the CD case, it hinges and folds causing the relay contacts to either open or close which then activates the solenoid, the solenoid slips out from under the shoe box, the shoe box falls, the creature is trapped.
The relay contacts are connected to the 'top' of the inverted shoe box and the CD case cover so when it hinges the contacts either open or closed.  With the solenoid energized all the time the contacts would open and the solenoid spring would pull back moving the shaft which then releases the inverted shoe box and it falls on the top which traps the rodent.
If you dont want to expend the energy, then perhaps a solenoid that pulls in when the relay contacts close and thus releasing the inverted shoe box and it falls.

In case you are wondering if this works, it works, tried and tested over several years.
The one catch i found is if you use a plastic shoe box you cant leave the rodent in there too long before you do something with it because it can slowly chew it's way out.  That means if there will be a lot of time before you can release the animal you would have to use a stronger material like aluminum.  An inverted aluminum box would be good i think, with a extra weight attached to the upper side to hold it down once it falls.  The box is tilted up so only one end is above ground like a lean to tent.  The bottom has to be metal too if you cant get to the animal fast enough.  So you have something like this:

[attachimg=1]

BlackICE:
I suspect this may work some of the time but not all of the time. The Trap design I've been using is 100% effective and kills most rats within less than 15 minutes from when they first see the trap. The longest living rat that's saw my trap died in 2 days. There has been zero rats that saw the trap that lived. Trap designs often fail where the rat doesn't trip the trigger, avoids it all together, or is trapped but escapes. The Trap design I use the rat doesn't need to touch anything, it only needs to be curious enough to poke his head in the right location and it's dead. You never want to give a rat a second chance because they're pretty smart and never fall for the same trap twice. Also I don't want to have to deal with a live rat, only dead ones. If you are curious and not repulsed by morbid videos you could do a search on YouTube for rat trap Chronicles. It will demonstrate my rat trap in action. My goal is to duplicate a similar trap but to lower the cost and size so that I could deploy 10 plus of them around my property without killing other animals besides rats.

If I can't think of a suitable design that's doesn't use a microcontroller I believe I have a plan where I can use a Firebeetle ESP32 with three AA batteries that should work. The advantage of using the esp32 is I can have  periodic reporting of the battery and trap status sent over wi-fi to alert me when the trap needs servicing. Additional cost will be about $10.

ledtester:

--- Quote ---...  and Arduino that activates a relay to trigger a modified snap trap. ...

--- End quote ---

You mention using a tool battery -- what voltage is needed for the relay?

BlackICE:
The tool battery is 12 volts in used to activated 12 volt solenoid. Running with less than 5 volts with three batteries that won't be possible. It's difficult to find a low-cost powerful enough solenoid that would work with only three double A batteries. So I'm thinking of using either a 5 volt Servo motor or muscle wire as an actuator.

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