Estradin Effect-1 Flanger | Эстрадин Эффект-1 Флэнжер приставка к электромузыкальным инструментам, June 1989, made in USSR

Link: sovietguitars

Produced in the USSR on "Estradin" military radioplant (famous for its Estradin-230 & Altair-231 synths) in 1987.
Suitable as signal processor for analog synths, drums, guitars, vocals or for any type interesting sonic experiments. It has standard 1/4TRS "Jack" for In, Out, Direct Out, also a switch between two bias modes. LED is rate\freq synchronized.
Powered by 220 volt. 
Some interesting specs of that flanger is a shift switch.
Actually that switch is used to transfer delay time control
from automatic to manual mode or vice versa.

The knobs: Rate, Depth and Brightness.
Button: Flanger
Inputs\Outputs: In, Out, Direct Out on standard 1/4'' jack. 
Switch between modes: auto and manual mode of flanger.
Power source: 220 volts

Owner's Manual & Schematic: