Hi Chris @chris101 and Frank @Frankje,
My electro-mechanical tremolo works as a tremolo and also as a vibrato.
When connected to the filter bit after an oscillator it changes the volume so you get a WAH WAH effect, as shown in my project mentioned above.
And when it is connected directly to the input of an oscillator it changes the tone of the oscillator instead.
I am not sure how to call this gadget then, there seems to be a lot of confusion on the internet about the real definition of these effects. Vibrato and tremolo are mixed up a lot, even by specialists knowing much more about music then i do. So I could call it a vibrolo. Ha.
Making a real LFO would be nice, it is a great addition to the KORG Littlebits set.