Dog & Cat Communicator

A dog and cat communicator? Try it, you might be surprised! Trainers tell us that dogs and cats respond to high frequency sounds – higher than we humans can hear – and you might just hit on the right note to train your pooch to come in for dinner.
A simple modification turns this project into an alarm – which can be used to surprise unwelcome visitors or warn you without them knowing.

You will need these components
Resistors:
One 100 ohms (brown – black – brown)
One 1.2k ohms (brown – red – red)
Two 10k ohms (brown – black – orange)
One light dependent resistor (LDR)
Capacitors:
Two .01uF polyester ‘greencaps’ (for the dog & cat communicator only)
Two 0.1uF polyester ‘greencaps’ (for the burglar alarm only)
Diodes:
One protection diode (1N4002 or similar)
Transistors:
Two NPN type DS548 or similar
Miscellaneous:
One battery clip
One 8-ohm loudspeaker
Two 12cm lengths insulated hook-up wire
One 5cm length insulated hook-up wire
Three lengths of tinned copper wire
17 self-tapping screws with washers
Baseboard & project overlay No. 7