Sometimes something old is new again. We all love the optical tremolo effect on Fender amplifiers (though it’s not used that frequently), but here’s another way to get the same effect using an old record player and vinyl record.
555 timer IC (Jacob Ellzey) used a gutted record player, a light bulb, and a few electronic components to create this very cool tremolo effect. The simple circuit consists of a voltage divider and low gain amplifier connected to a photoresistor and a 555 IC timer circuit for driving the incandescent bulb (complete instructions here).
The key to the effect is a vinyl record with large tabs cut out of it though. As the record spins, these cut-outs block and unblock the light from a small incandescent bulb. A GL5537 photoresistor is mounted on the tonearm where the cartridge would normally sit. This picks up the different light levels and passes that on to the electronics underneath the deck. It’s important to note that the effect’s sound can be changed by also changing the spacing and size of the vinyl cutouts.
There are also a couple of parameter controls as well with a couple of rotary pots mounted to the side of the record player for adjusting the depth of the effect, and output volume (just like you’d find on a Fender amp). He even added an external foot pedal for switching the effect on and off (again, just like. . . ).
What you wind up with is a very usable tremolo. Is it as efficient as just using a pedal? No, but it looks way cooler.