Notice that the contrast control (LCD pin 3), instead of using a typical 10K potentiometer, uses an LM334, which ensures a constant current of 200µA to ground (so the contrast does not need to be ...

For $26.60, you get a breadboard, wires, and all sorts of components like a buzzer, buttons, an LCD module, and a potentiometer.

Targeted for the smart home, this design leverages two PIC MCUs that use a wireless RF transmitter/receiver to control up to six relays and monitor two analog signals.