This is a nice little PT2399 based delay circuit. I would advise clicking on the vfepedals link in the sidebar. I like the interactive way he descibes his circuits. I also enjoy that it seems his main goal is to teach and he likes to share his knowledge.
From the VFE Website:
The BLUEPRINT is an analog-voiced delay pedal, perfect for warm, ambient delays that don’t muddy up your tone. The BLUEPRINT delay uses a unique EQ method that blends a dark and bright delay, yielding a warm tone without sacrificing clarity. An internal trimpot allows you to adjust the blend to brighten or darken the tone to your taste. Get up to 580ms of delay time, plus modulation for adding slight detuning, warbled chaos, or even pseudochorus sounds.
TIME: Sets the delay time from ~ 40ms up to 580ms.
ECHO: Controls the amount of feedback in the delay circuit, and therefore the rate of decay of the repeats. It has a range from one repeat all the way to self-oscillation for those spaceship-style sounds.
MIX: Mixes between the unaffected dry signal & the wet delay signal. Fully counterclockwise = pure dry signal, fully clockwise = pure wet signal.
LEVEL: Sets the output volume of the Blueprint. Up to 20dB of clean boost on tap, making this a perfect boost/delay for your solos!
DEPTH: Sets the depth of the modulation. Turn 100% counterclockwise to turn the modulation off.
SPEED: Sets the speed of the modulation. Go from fast warble to a slow detuning effect.
TONE: The internal TONE trimpot blends the delay between two signals, one with a bright EQ and another with a dark EQ.