Smart Cat Scarer

We have been using these cat scarers for a while now. Whilst they are quite cheap (about £15), they have two main problems:

  1. They are battery powered and the batteries really don't last very long, especially in colder weather.
  2. They can be triggered by people and when they are triggered, the in-built Passive Infra-Red (PIR) sensor flashes blue and (despite using ultrasonic frequencies) children and older people with good hearing can still hear them 'chirping'. Both of which are annoying.

We don't generally have an issue with cats in our garden but, they seem to like to use our front garden as a litter tray. This damages the plants and doesn't smell too good, so we would like to keep them away from this area. The cat scarer seems the best way to achieve this and as a dumb device it is effective.

Our goal with this project is to make these 'dumb' devices work much smarter and to eliminate the need for batteries. Like many of our projects it is essentially about improving quality of life.

Note:  This project is not monitoring when the cat scarers are being activated by cats in our garden. This is not a feature that we require.

Batteries

Each scarer uses four AA batteries and is therefore using 6V dc. We drilled a small hole in the battery compartment cover and ran two wires through this hole, so we could solder them to the battery terminals. We then sealed the wire entry point to keep moisture out.

We can now control whether the device is on or off by switching the power via the wires.

Power Control

We are using an Arduino to switch the power on and off, using one of our output boards to handle the higher voltages and currents involved. These work at 12V dc.

We are using a dc-dc converter to step down the 12V dc voltage to the 6.5V dc required by the cat scarer. These are very efficient, reliable and can be cheaply bought on sites like eBay. Most have an adjustable output voltage, so they can be used for many applications.

It would be very easy to add another scarer, to cover a larger area and this would simply be added to the dc-dc converter output.

Models & Intelligent Control

Our smart home models the cat scarer as a simple appliance that can be turned on or off. It is therefore really easy to configure the cat scarer's behaviour using our software controller, one of the inherent capabilities of our Home Control System. It has been configured to be on by default and off when the porch or drive is occupied. It's that easy to do! There are many things that drive occupancy of these zones and our Home Control System handles the complexities behind this for us. It simply means that when people are present, they will not be annoyed by the cat scarer.

When we activate our scene called 'Guests Arriving', the cat scarer will also be switched off automatically for about half an hour.

Insight

Smart home occupancy detection is a core part of the intelligent smart home and hugely important in delivering a great user experience. Simple occupancy based control of appliances like this improves the experience further.

Ultimately, this automation is about improving quality of life. We get a front garden that is not soiled by cats and we are not annoyed by a cat scarer going off when people are present. It is a cheap and simple solution enabled by our contextual smart home.