Friday, November 02, 2007

Quantum mice - a watched mouse never gets caught...

About a week ago we discovered we have mice in the eaves, a situation SWMBO asked me to remedy in my own time, or at least that's how I chose to interpret her hour of screaming hysterics...

So, following on from a design for a mouse trap Ste and I made about twenty years ago, which caught a dozen mice in its first four hours of operation, I hacked together a transparent box with some bait, an infra-red beam to detect the mouse and a solenoid operated trap door to catch it. This was then placed in a likely spot and an infra-red video camera rigged up to watch the mice being caught.

About an hour later the first customer turns up. After a cautious sniff around the outside it stuck its head and shoulders into the box and rooted about, not going far enough in to break the beam. Fair enough, perhaps mice have grown more cunning in the last twenty years... Nil desperandum - give them a chance to get used to it.

A bit later another mouse appears and goes through the same process... Perhaps they don't like plastic boxes?

Then one turns up and gets inside the box - I sit poised - surely this is it? But no, somehow the bloody thing doesn't trip the trap, and leaves. Bastard, I'll get it next time... But no, it's back, and this time it brings a friend. To cut a long story short they explore the box, they party on down on the bait, they jump about, have sex, snooze a little, and at no point does the bloody trap door close. After a bit they get bored waiting for something to happen and wander off, presumably giving the place a bad review.

Only then does it occur to me that a mouse trap that relies on the mice breaking an infra-red beak in a transparent box is probably not the best thing to watch using an infra-red camera that has about a dozen high-intensity infra-red LEDs built in as illumination... Doh!

Got 'em when they came back an while later - amazing the difference a bit of cardboard around the camera makes...


  1. Caught six mice so far, though two of those fell to a new, improved, microprocessor driven trap... That's progress for you. Twenty years ago I used a CMOS invertor package and some passives, now I use a micro and rather fewer passives. For the record, I think the CMOS invertor version used less power and worked just as well...

  2. Caught over a dozen of the bloody things over xmas and no end in sight.

    The degenerate freeloaders must be having far more fun than I am... Bastards...

  3. Surely you have a compressor at Crem Towers? Get some duct of about 1.2 mouse diameter, angle one end up at 45 degrees in the direction of the neighbors fence. Attach t'other end to mouse trap. Mouse breaks beam, trap shuts, compressed air dumps into trap....
    You get the idea.

  4. Do you think it would scale up to 1.2 wife diameters? The mice don't bother me half as much as her hysterical reaction to them...

    [sigh] It would never work. The neighbours would send her back :(

  5. It would scale, but the last people to try it got into an awful lot of trouble when they exported their finished product to the middle east.

    So you married a Mouse-Screamer. Still, look on the bright side. Take it as inspiration. There's a computer game in this. SWMBO jumping from chair to chair in a frogger-esque attempt to get out of the house....

  6. Why am I reminded of Vogons?

    The bloody woman's intolerable. I only got three hours sleep last night because she woke me up after finding some mouse poo in the kitchen.

    After a few choice remarks I went back to bed and then an hour later one of the bloody things ran across the living room and I was up again...

    Actually, it wasn't the running mouse poo so much as the mouse it was attached too that bothered her.