The Wobbler - a custom vibrato thing

This pedal is now available to buy, having been re-named "Inkcap"!

> Link to video

> LInk to store

This pedal was commissioned by Phil at Pedal Experiments, who also made the video and you should definitely be subscribed to his channel.

I'm using an Electric Druid StompLFO chip. You'll likely recognise the waveforms, this chip gets everywhere these days.

The pedal uses a method similar to the Little Angel chorus by Rick Holt to create the vibrato: modulating the PT2399 via the VREF pin. This means we can keep the latency down, but we also have to use the "anti-latch-up" circuit so the delay chip doesn't freeze up when turned on.

Unlike the LIttle Angel I have a vactrol (controlled by the LFO) that allows +5v to pass to the VREF pin. After much experimenting I'm fairly sure this is the best way to get low latency while also maintaining the shape of the LFO waveforms.

Another interesting aspect is the Tone pot, which follows this topology, making an active 2-pole filter.

Schematic

This schematic also includes a Chorus switch (ON-OFF).