Coded something new during last weekend, another classic effect which sounds great with many instruments:

12 stage mono phaser with internal (built in) LFO or an external modulation input

Click image for larger version. 

Name:	phaser_internal.png 
Views:	21 
Size:	88.4 KB 
ID:	23805

Link to code:
https://github.com/hexeguitar/t40fx/tree/main/Hx_Phaser

Sound Sample (drum loop, stereo guitar track, synth)
https://soundcloud.com/hexeguitar/te...2-stage-phaser

Internal LFO is active when there is no modulation input signal connected. The waveform is similar to parabolic (often described as hypertriangular in hardware effects). Instead of a usual rate/depth controls the depth is set by two params: top value and bottom value. Incoming modulation waveform, internal or external, is then scaled to operate within that range.

Effect is not really cpu and ram heavy. T40 reported only 1% load.

I/Os:
input [0] - audio in
input [1] - modulation in (int16)
output[0] - audio output

One interesting use case of the phase shifter is a vibrato effect: set the feedback to 0.0, mix to full Wet (1.0) and adjust the top/bottom/rate values for the LFO to get different vibrato sounds.