Electronics is about controlling the passage of electrons through semiconductors and thereby creating desirable outcomes. Mini projects for electronics and communications can encompass practical projects for use with telephones and fun projects that integrate sound and light. At a slightly less serious level, they can also include paranormal experimentation, ESP and many more phenomena.
Electronics and microcomputers expert Fred Blechman (see Reference 1) has built several gadgets incorporating electronics and communication. These include a telephone hold button, remote ringer, recording beeper, FM transmitter and line analyzer. Blechman recommends using parts kits as the circuit boards come etched and drilled, although you can print your own board if you prefer.
The telephone hold button takes about five minutes to make, says Blechman. The telephone ringer is constructed easily with point to point wiring. The recording beeper does not even need a printed circuit board. The FM transmitter does not need a battery, whilst the line analyzer can be made from parts you probably already have.
Music and Light Show
Expert electronics projects builders Earl Boysen and Nancy Muir came up with a fun design for a circuit to switch on LEDs, or light emitting diodes, in response to music. (See Reference 2.) They set up two rows of lights that illuminate in response to different sound frequencies. The trick is to use a circuit that uses an electret microphone that converts sound into electrical signals. An operational amplifier picks up the signal from the microphone. The circuit is split so that the upper half switches on the LEDs for high-frequency sound and the lower half lights up LEDs for low frequencies. This means that every piece of music produces a different light show.
Electronics hobbyist Newton C. Braga offers a slightly tongue-in-cheek approach to mini electronics projects (see Reference 3), with a range of projects that includes instrumental transcommunication (ITC). This is the phenomena of unintentional, electronically generated noises resembling speech. Braga's experiments also include Kirlian photography, where images are created with electrical voltage. Further, the author offers "plasma" experiments in which a sensor is made with a candle. The flame is in contact with a circuit and conducts electric current, thereby keeping the circuit oscillating. The changing resistance of the candle changes the frequency of the oscillator, with interesting effects.