This is a simplified version of a Univibe.
Univox Univibe was one of the first phasers available in 60s.
You can hear it on such tracks as Jimi Hendrix - Machine Gun; Pink Floyd – Breathe; Robin Trower - Bridge of Sighs.
In 2001 John Hollis designed the Easy Vibe, substituting Univibe transistors and light bulbs with opamps and leds.
This circuit allows to get a Univibe sound at much cheaper price.