We have a cabin that sits empty a portion of the year. We have arrived to find everything covered in mouse turds and urine. Then spend the first day cleaning everything. We have even found afterbirth on the sheets of a bed once, quite disgusting. My wonderful wife now puts everything in plastic totes when we leave to keep the mice out.
Regular mouse traps work great. Problem is when you set 15 traps and catch 15 mice but there are 25 in the cabin, you still end up with mouse crap everywhere. Poison also works well but them sometimes they crawl under the stove or somewhere inaccessible and die. Then you have to deal with the stink of dead mice. Sometimes they even become immune to the poison and you get little green mouse poison turds all over.
I tried the beer can smeared with peanut butter on a dowel over a 5 gallon bucket. That worked pretty well but some of the mice just wouldn’t venture onto the can so we still have some of the mouse mess. I found a design on the web that had an enclosure over the bucket with a trap door that was triggered by a motion sensor to trigger a motor to pull open the trap door. I thought I’d try and build one of those.
I spent a few hours on Fusion 360 modeling program and designed the enclosure and trap door to print on my 3D printer. Decided to use an Arduino controller and one of my spare servos to pull open the trap door. Bought a small inexpensive motion sensor to detect the mouse. Used a rare earth magnet to hold the trap door closed. Added a long pull arm to the servo and a string attached to the trap door to pull it open then push it back up to magnet. It took a lot of adjustment to get the magnet to hold the trap door closed but weak enough to allow the little servo to pull it open. It worked ok until the temperature dropped, then the motion sensor kept false triggering which seemed to scare the mouse away from the trap. I replaced the motion sensor with a thru beam photo eye detector. This worked better except the photo eye drew too much current and drained the batteries too quickly. Below is the trap.
While scouring the internet for a better sensor, I found the walk-the-plank mouse traps. Great concept but a lot of reviews that it was hard to get the magnets adjusted just right. Seems they wok well but occasionally get stuck then the mice would eat all the bait. I thought I’d take that concept and marry it with my original one. So after a few more hours on the design software I came up with a walk the plank style but using a servo to drop the plank. I still needed a better sensor. Looked at proximity switches but they are quite expensive and heavy for the end of the trap. Finally came across the TTP223 touch key switch module. It was designed to work with Arduinos as a touchless button. They sense any dense object that come in close contact to the sensing area. I bought a few and tried them out. Seems to be the perfect solution to my problem.
After many 3D prints and many redesigns to get the sensor in the correct spot, servo mount correct, cam working properly, I had a decent working prototype. I put it in the cabin and caught 2 mice the first night. Was glad to see that a mouse would trip the sensor. Still had a battery problem. Did some intense testing and found the servo was draining the battery even though it was not enabled. Added some circuitry to cut the power to the servo until the sensor was tripped. This seemed to do the trick. The whole setup was only drawing 180 micro amperes at rest which means 4 AA batteries should last many months depending on how many times it is triggered.
As Ralph Waldo Emerson once wrote “If You Build A Better Mousetrap The World Will Beat A Path To Your Door”, I thought why not try and sell my design. It was hard to come up with a price. It took about 6 hours to print the trap and had about $22 in parts. Took quite a bit of soldering to get it all put together. I built a few and put them on Ebay. After a couple weeks I sold two. The same guy bought both, Shawn Woods. He contacted me later and said he was going to make a video of it and put it on youtube on his MouseTrap Monday. I had seen some of his videos and thought that would be the best free advertising I could hope for. He said to be ready for a ton of orders. He wasn’t wrong. Had about 50 people wanting to buy it. I scrambled to get parts and build the traps. I decided to build my own printed circuit board (pcb), that would cut the soldering time considerably.
That was another learning experience. I used the Autodesk Eagle software to design the board. Luckily it worked out on the first try. It is more expensive to build my own pcbs than using the inexpensive Chinese arduino pro mini boards but saves valuable build time. Plus I’ve ran into problems with some of the inexpensive pro mini controllers. Making my own, I can assure the quality.
Have been making small improvements from customer feedback and feel we have a good quality product now. Had a few requests for a larger trap that would work for rats. We have developed one but have no rats around here in Wasilla to test it on. Hoping to get Shawn to test it in his surprisingly rodent filled barn.
The Rat trap is now live. It is a longer more beefed up version of the mouse trap. The batteries don’t last as long in it as the mouse trap since the flap is twice the weight, it takes more power to lift it. The mouse trap seems to still work with the battery voltages as low as 4.4 volts but the rat trap needs at least 4.8 volts.
We are working on a new version of the mouse trap. Had a suggestion from a viewer which lead to this new design. Basically the flap is raised up above the main body and extended over the body so the whole plank will tip giving less opportunity for the rodent to hold on. Still in the prototype stage but it is looking promising.
SIDE NOTE: We have been testing the battery life in a couple mouse traps starting 11-23-20. Triggered it every day for the first month now just triggering every couple days or once a week. The battery is still at 5.37 volts as of 5-27-21. The servo will continue to operate down to 4.6 volts. The 4 Duracell alkaline batteries voltage started at 6.42 volts. The traps have been indoors. Battery life will degrade much faster in colder temps. 6 months and still going strong.