Elmo omnigraphic 253af slide projector, similar to a kodak s-av 2000. Turn on, slide change at 10 second intervals, turn off. Recorded on a marantz pmd 661 with a rode nt4, 250 mm above centre rear of projector, angled down at 45º. I needed this sound as part of an audio-visual that mimics a slide show. I chose to record a 10-second change interval (instead of a shorter interval) because that allows me to razor the waveform between changes, and then extend (or reduce) the time between changes. Too short a time interval between slide changes means you'd have to add motor/fan sound between every change.
Author: Guyburns