This project is a DIY small solar cat repellent mounted inside a plastic trash can you can place it in anywhere in your garden, very easy to mount and without microcontrollers.

The device emits a continuous sound and lights up two green LEDs (very bright at night) whenever it detects the heat of an animal nearby.

It is really effective and I use it to protect my planters where cats usually pee.

I hope you like and be useful for somebody.

Step 1: List of Materials

Plastic trash can
Two solar panels (6V, 100 mA)
One pulse generator
One passive buzzer
One PIR sensor
One NPN transistor
One 1kOhm resistor
One little switch
One rectifier diode
One tiny breadboard
One 3,7V battery (1200 mAh)
One micro USB battery charger
One step up boost DC-DC converter
One doubled side PBC board
Digital multimeter
Wires

Step 2: The Circuit

In the first Fritzing diagram you can see the main circuit without the power supply. Basically it uses a NPN transistor to activate the buzzer when the PIR sensor detects the infrared light emitted from an animal. To make sound the buzzer I have used a pulse generator device (PWM) based on the NE555 chip configurated as monostable. To produce a sound in the buzzer, use a little screwdriver and move the screw in the pulse generator device until you hear a sound.

The power supply is represented in the second Fritzing diagram. To adjust the output to 6V, move the screw with a little screwdriver in the setp up boost converter. The power consumption is very low, so, two solar panels (6V,100 mA) are enough to keep working the device 24 hours.

In the following video you can see how it works.

Step 3: Mounting the Device

To mount the device we have to do the following steps:

Open several holes in the plastic trash can to place the leds, the buzzer and the PIR sensor
Glue the the tiny breadboard inside the trash can
Connect the wires following the Fritzing circuit
Connect the solar panels to the power supply PCB
Finally, connect the power supply PCB to the tiny breadboard and insert everything in the trash can

¡That's all!

Thanks for reading this instructable.