[Dino] recently sent us some info on his latest project, a 555 timer-based slider synthesizer. The synth was built to emulate the sound made by playing a slide whistle, and also as an entry into the 555 Design Contest, which is quickly coming to a close. If you’re not familiar with a slide whistle, just spend a few minutes on YouTube looking for clips of Sideshow Bob – it’s ok, we’ll wait.
The circuit is pretty simple, though the implementation is quite clever. While traditional slide whistles require the user to blow in one end, this electronic version operates using a LED and photo cell. When the main switch is closed, the 555 timer is activated, and a tone is produced. The pitch of the tone is controlled by the LED as it slides in and out of the tube. The more light that hits the photo cell, the higher the pitch, and vice versa.
Continue reading to see a quick demonstration of [Dino’s] slide synth, and be sure to check out his other 555 contest entry we featured a short while back.