Simple LED/sound/email alert for small animal trap (100ft distance)

Hi all,

I have very little experience with arduino, but understand the basic concepts. Looking for guidance on a rather simple project with several possible approaches. My main question is how to do it with minimal cost and fuss. I've seen similar kinds of projects, but they all seem much more complicated / expensive than necessary for my needs.

I have a Havahart small animal trap for the large, vicious rodents that invade my garden and eat my precious flowers.

The trap is about 100ft (30m) away from my door, but it's blocked by a tree, so I have to walk over to the trap several times a day to see if there's anything inside. I'd like to set up a sensor that would detect whether the trap was closed, and if so, notify me in some way. Though the rodents are my sworn enemy, I don't wish to extend their suffering any more than necessary.

I see three possible setups.

  1. The ideal setup involves no long cables: a wifi-enabled MCU, powered by batteries, connected to a sensor that detects the open or closed state. If the sensor reports a closed state, it would send me an email.

I could use a battery and keep the device in sleep mode most of the time, waking it up every 30-60 minutes during the day to check the trap and sleeping all night. It would be best if the power could last for about a week, so I don't have to keep changing the batteries. It is probably close enough to get a wifi signal; definitely close enough if I use a wifi repeater, which I happen to have. However, the unit would have to be weatherproof.

  1. I could also use a long cable between the sensor and the house, keeping the MCU plugged into mains and activating an LED or speaker on the MCU inside the house. This seems like the cheapest, simplest solution, but I'm not sure of the feasibility of running such a long cable.

  2. Or keep the MCU outside near the trap and run an extension cord over there, and then another cable back to the house to trigger an LED. But that seems like more cabling than necessary, possibly requiring two MCUs, and would require weatherproofing the outdoor MCU.

My questions are as follows:

  • Which of these three is the best approach? Or is there another I'm missing?
  • What sort of sensor is best to determine the state of the trap?
  • In the event I use a long cable, what sort of cable is up to the job?

As much specificity as possible regarding the recommended components and links to relevant tutorials / projects / other resources would be enormously helpful. I'm not too worried about tackling the actual project once I have the approach and components figured out. Thanks so much!

I'd suggest an ESP8266 dev board (Wemos, Adafruit Feather HUZZAH,nodeMCU etc) coupled with the IFTTT Maker channel (Webhooks Integrations - Connect Your Apps with IFTTT) to do the notifications. Search the internet for "esp8266 doorbell" for lots of examples to get you started.

Assuming your trap has a strong mechanical component for slamming the door on your furry adversaries I would imagine it would easy to fit a mechanical switch or contacts that would close and trigger the process. If you arrange it so the ESP8266 is held in the reset state until the contact closes it should run for a long time on batteries.

Theres some nice weatherproof boxes available (search for "project box" or "electrical box") or you can just wrap the whole thing in a few layers of duct-tape to keep it out of the weather.

Awesome! That should be all I need to get started. The trap has a handle on top that should provide enough force to trigger a contact. Will post as it comes together.