|
Mouse trap
|
Two over engineered mouse trap are presented here in this section. The first trap uses a laser to trigger the trap and the second uses a contact plate. Both traps are non-lethal and are designed to trap the mouse only. The fate of the trapped mouse was up to the user. The design of the mousetraps was motivated by a rodent problem that occured around 2004 and 2007.
|
|
Table of contents
- Introduction
- Laser activated mouse trap
- Experimental results
- Contact plate activated mouse trap
| |
New catch - 05/09
[Top]
Sometime around 2004 our house began to experience a mice problem. The usual approach of using a mousetrap was taken. However, we noticed that in some cases the mice were able to nibble on the bait without setting the trap off, despite tying the bait tightly with a string. Poison was not considered because the idea of a dead mouse corpse in an impossible to reach spot is not very appealing. The problem at hand called for a better mouse trap design. I wanted a trap that did not require the mouse to exert any force. Using a laser tripwire was an obvious solution. A laser is projected onto a light sensor. When the mouse crosses the laser and breaks the beam, the circuit will activate an actuator and trap the mouse. The trap was built from MDF wood and electronic parts bought from Jaycar.
In 2007, a whole new batch of mice emerged. These mice were much bigger than previously encountered, in fact, they were probably rats. I decided to make a new mouse trap because I wanted to try a new design with new features. The second trap was bigger and used a highly sensitive contact plate instead of a laser. The trap was also made from clear perspex allowing the user to have a clear view of the trapped mouse.
[Top]
The initial design for the first mouse trap is shown in Figure 1. The actual trapping mechanism is the sliding door at the front where the mouse enters. It is held up by a rod connected to a magnetic actuator that pulls the rod when energised. When the rod is pulled in, the sliding door will drop. The door is made from steel so that it is heavy enough to overcome friction and drop smoothly.
Figure 1: Initial design for the mouse trap.
The final product is shown in Figure 2,3,4,5. Not the most elegant wiring job. It's powered of a 12V adapter. Figure 1 shows the main entrance where the mouse enters. Figure 2 shows the back of the trap. There is a clear sliding door (peep hole) to allow the user to see the captured mouse. Figure 3 shows the metal sliding door and the circular hole where the rod connects to. I had to block the hole with a piece of wood because the mouse was able to squeeze through it! Figure 4 shows the inside of the trap after some usage. The floor is discoloured from mouse urine. Some of the wood inside was chewed on a bit as the mouse tried to escape. In hindsight, using MDF wood was not a good choice.
|
|
| |
Figure 2: View of the main entrance.
|
Figure 3: Back view showing the peep hole.
|
|
| |
Figure 4: Sliding door. The circular hole is where the rod connects to.
|
Figure 5: Inside the trap. The floor is discoloured because of mouse urine.
|
|
| |
[Top]
Figure 6 shows a captured mouse (photo taken through the peep hole). I used peanut butter for bait. That chubby furry mouse can actually squeeze through the circular hole shown in the background if I didn't block it off. Around 5 mice were caught in total. The fate of the mice varied. Some were killed by mum (I don't like to kill unecessarily, but too lazy to do something about it at the time). Most were released to a nearby quiet park by me. I know, I'm probably just passing the problem onto someone else, but hey, at least I'm guilt free. There was one mouse that I accidentally left too long in the trap and it starved to death, laziness on my behalf. I kept putting off releasing it at the park.
Figure 6: A successful catch.
[Top]
With new and bigger mice popping up in 2007, I decided to keep a similar design to the previous trap but with a new trigger mechanism and replaced the material with aluminium and perspex, as shown in Figure 7,8. Since the circuit only activates when there is a connection between the contact plates the whole thing runs off a rechargable 9V battery, making it quite portable compared to the previous moue trap. Though, for some reason the battery only lasted 3 days, probably due to some current leaking through the transistor even when the circuit is off. Figure 9 shows the two contact plates used to trigger the trap. I added some rubber pads to the contact plate because I did not want the circuit to be on all the time should the mouse decides to urinate. Although the circuit worked when I touched the contact plates, I wasn't sure if the mouse's feet would conduct enough to trigger the trap.
I used expoxy glue to join the perspex to aluminium but did not take care to clamp it. Some of the bits are falling apart as a result. Lesson learnt, use screws instead.
As good as the new trap may look, it sadly failed to catch a single mouse. The new mice did not once attempt to go and take the bait. Could it be because the trap is transparent and not a dark box? What were the mice thinking when they saw the trap? Hmmm.
|
|
|
|
|
