Well the last one I had next doors cat peeed against it so in my case the answer was No.
Now I have a big GSD. I swear she would would ingest a cat....she hates them.
Don't get any cats now and the blue tits have always been able to successfully rear chicks which they could not before.

The answer is yes.
That is if you use the type that sends out a high pitch sound that cats don't like.
They come as battery operated or mains (recommended).
I have three around certain areas of the garden and have not had cats fouling the garden for about three years now.
The battery ones activate when cats pass by them up to a hundred metres and the mains one works continually.
I got them from a garden centre.

I wonder if they work as a squirrel scarer? Magpie scarer? The squirrels (possibly just one) bury nuts everywhere, then the magpies swoop in and dig them up again. It would be comical if it wasn't damaging so many plants.

B&Q were selling rat detectors/scarers last week. Is that the same thing? I was think of putting one in my cold frames to stop mice chopping off new shoots and flowers. Do they work for snails and slugs too :-)
Some years ago I stayed one night in a down market hotel/motel in the suberbs of Milan, when the city was full in fashion week. Above the bedroom door was a box labelled Rat something, and the rest in Italian, with a red light on it. I never did decide if it was a rodent scarer. Fortunately I had enough wine with the meal to prevent me worrying too much.

Brian

Re; cat scares. Product PESTBAN.
These will keep out the following: Cats,Dogs,Deer,Rats,Mice,Rabbits and squirrels subject to what setting you have the device set to.

I want to scare cats from my bird feeding area - do they scare away birds too?

No they don't scare away birds.

iam in the process of buying one now from a place called primrose/london its advertised on the net as a mains cat repellent 100 with a seperate pir i hope its the same and works the cats are killing off loads of expensive plants. if this doesnt work has anyone got a shot gun for sale ha ha

Hi Can anyone tell me if I can get a cat scarer that does not effect dogs

"Can anyone tell me if I can get a cat scarer that does not effect dogs"

A large dog??

I am owned by a very dear tomcat that has been part of the family for 13 years. He is an integral part of my pest control program, making a large number of rats pack their bags and bugger off from the pump house. But he does prefer my vegetable patch to his dirt box when it comes to doing business. Any suggestions for keeping my seedlings safe while not barring Tiddles from the manor completely?

a dog, any dog

There is now a battery operated PIR operating a water jet/ sprayer on the market .. that you connect to a hose pipe and set to an entry point to cover ....cats hate the water spray .
My pal has successfuly used three units in his large enclosed garden to keep the moggies out .

google " PIR cat deterrent "