Gene Roddenberry’s original TV series of "Star Trek" broke quite a bit of new sci-fi ground in its day, with imaginative thought-provoking stories and a collection of interesting characters: Captain James T. Kirk, science officer Spock, engineer Scotty ("you canna’ change the laws of physics, Jim") and so on. Small wonder it spawned a number of spin-off movies and a follow-on series, along with a huge following of ‘trekkie’ fans who seem just as dedicated today as they were 30 years ago – no doubt helped by the release of all the original episodes on DVD.

Fig.1: the circuit uses an HK828 sound recorder chip (IC1) to store two different "Starship Enterprise" door sounds. This drives audio amplifier stage IC2 to replay one of these sounds when switch S1 or S2 is momentarily closed.

Of course, along with those original episodes, many keen trekkies also like to acquire "Star Trek" memorabilia: replicas of the costumes worn by the "Enterprise" crew, copies of Mr Spock’s pointy ears, fake phaser guns and so on. They also like being able to generate some of the distinctive sound effects which helped make the first series so memorable.

So if you have a friend or relative who’s one of these dedicated trekkies, you might want to build this project for them – or for yourself! It recreates the "ssshhhHHHh-thump" sound that always accompanied the sliding power doors opening or closing on the "Starship Enterprise" and can be triggered by either pressing a pushbutton or closing the contacts of an external switch (eg, a reed switch activated by a bedroom door or sliding wardrobe door). It’s also quite easy to build and can be operated from a 9V battery or 12V plugpack.