Tonecoder-sharktooth

A novel effects box

A year or two ago I connected a photocell to a time delay circuit and found that modern light bulbs will modulate the playback frequency. They oscillate at audio frequencies to reduce energy usage but the downside is that it disturbs natural brain function.

Tuning my instrument to the room light (carrier frequency) gave a nice tonal resonance with interesting sideband frequencies. This is essentially fm resynthesis, with the modulator set at fixed frequency.

The pt2399 has a VCO input, so to make a tunable arangement of this you can insert an oscillator directly to modulate the signal. 

I've been designing a box to make use of this effect. After discarding the first circuit board because of noise issues I rearanged the layout

and made two prototypes with various features and concluded with the most simple arangement- two tuning knobs. There is wide range oscillator control- for the carrier, and an attenuator. Its a special effect when full on and but i like to use it almost fully attenuated to enliven the harmonics and tighten the sound of slacktuned guitar.

The box was made from an old rimu door. I hollowed it out enough to house the electronics and cut some iron sheet for the faceplate. The sheet metal got a wee brittle from to much hammering and split on the top edge but otherwise it came together well and it feels nice to hold. The first prototypes had an inlayed plate that I milled with the cnc but I prefer the feel of the iron folded over the wood.

The PT2399 circuit give great depth of modulation and clean sound with some compression. Its still a touch noisy from the internal clock aliasing the modulation oscillator.