Cat Repeller

On-Guard Sonic Cat Repeller type 72505 ex Bunnings distributed by Brunnings.
Also sold under various names.

Some details for purchasers and hopeful repairers like me with certain tendencies toward detail.

Does it work? Yes as an movement detector and ultrasonic sound source.
Dos it repel cats? Don't really know, no double blind tests here, but it seems to keep them away from my vegies.
Had it for two months.

Booklet says "For Outdoor Use Only".
It is not waterproof.
Mine had some water drops seep out of a seam when I was moving it around the garden to reduce “cat familiarity”.
Designer made the bottom part partly waterproof, but the top is marginal, and the sides are not.
The bottom pull-off sealing cap is just a rain catcher, so discard it.
The plastic stand is a joke, as it is too flimsy;binned.

I could not pull this thing apart to dry it out.
Eventually, with nothing to lose as it had water inside, I broke four screw tab fittings and "disassembled" it.
I drilled two 2.00mm drain holes in the bottom.
Reassembled, after drying, and a spray of "anti-everything nasty" (Lanolin Spray) on the two PCBs, using top screws and a few dabs of Sellys AllFix glue.

It is assembled with two PK screws on top, and then with four PK screws at the base, and two hidden screws under, and inside, the top plate.
The top screws are under little green plastic plugs, easily removed.
The bottom screws are under four green plastic plugs, all recessed 15 mm, and which I could not remove, even with force.

If you really must pull it apart, try WD40 to loosen those four bottom plastic plugs, then try using a long screw as a puller to axially pull out the cap, by screwing directly into the centre of the plug cap.
Centre punch it first.
You cannot drill the bottom caps, as I did, as the drill bit destroys the screw head cross point, and a screwdriver is then useless.

Failing this.
Remove top screws, bend top plate back until it breaks the two top rear (hidden) screw plastic tabs; top will then separate.
Then bend the back of the bottom until those screw tabs break away, leaving the front still attached.
You are in!
Drain and dry. Reassemble.

I tried a plastic bag over the whole thing to keep rain out, but it reduced the detector sensitivity.
Sensitivity is critical, as the Radar Cross Sectional Area of a cat is small WRT a vegie grower.
I then made up a rain “hat” for the top plate out of scrap 2mm polycarbonate.

The device uses two 9V batteries in parallel, and draws 300 uA in "search for cats" mode, and 30 mA (averaged on an analogue VOM) on "blast that cat".
My unit still has original batteries after two months and they are still OK at 8.9 V. Amazing.
Caution on using a mains DC plugpack, as the power socket is negative to centre pin, not the usual arrangement.

Frequency is 22kHz start, ascending in bursts of slightly higher frequency each burst for five seconds, then in descending frequency in more bursts.
About a twelve second overall burst of ultrasonics.
Across the piezo transducer is 3 V pp when ON, as per CRO.
The waveshape is about halfway between triangular and sine.
I don't know the transducer impedance, so cannot determine the power exactly, but if if it is say 8 ohms, then cats are hit with about 125 mW (Fourier not explored).
This is probably just enough to really get their attention, but not enough to instil uncontrolled body function.
When triggered you can hear only clicks from the piezo as it goes thru its "Andante in Z major" ultrasonic scream sequence.

Probably affects dogs, but I have not heard dogs reacting with a howl.
Easily detects a human at ten to fifteen feet or so.
Long term performance on pesky feline critters unknown.

For your amusement, curiosity, and it may be actually helpful to some.
Australia Felix

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