This is an electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. This relay can operate a power-to-open type electric strike with a shorting contact or a power-to-hold type electromagnetic lock with a breaking contact (we need the relay because these locks usually work with AC, not DC). The code can be changed any time after entering the current code.source

This is a lamp timer capable of operating two separate relay switches. Outputs can be in three (or restricted to two) states: OFF, delayed ON and constant ON. Delayed ON mode is indicated by the LEDs. The source code is easily customizable for your needs: set your desired delay time or disable constant ON state.source

This is the classic PIC16C84/16F84 programmer. The design is originally by David Tait.The programmer connects to the parallel printer port of your computer and requires external power. If you want to program a PIC you’ll have a hex file created by your assembler or created by someone else. You will also need to drive the programmer with some software. source

The interface uses a PIC16F876 microcontroller and not much else. It performs channel mixing, current limiting, and noise rejection. Push the stick forward, both motors move forward, move the stick to the left and the robot moves left. It makes the robot very driveable. You can use a wheel transmitter meant for cars to control it, in other words, one channel is throttle(both forward and reverse), the other steering. Speed control is smooth, and the H-Bridge transistors are sensed and protected cycle-by-cycle against over-current. Noise from the receiver, whether the transmitter is on or off, is ignored. Temperature sensing is also possible.source

This is Propeller Clock.A motor spins the “propeller”, and a small microprocessor keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs. It is an illusion, but it works nicely.source