Magic Eye Winker - EAM86

Old "Magic Eye" tube was used as a tuning aid for old tube radios. This "winker" is a circuit that wires its internal triode as a low frequency (~1Hz) phase-shift oscillator, where the oscillation can be viewed as the eye opening and closing. The 300mA to run the tubes' filaments is directly tapped from the 120VAC, thru a 6.8uf capacitor (which has a reactance of 390 ohms, at 60Hz). This is an ALL-TUBE circuit; NO SEMICONDUCTORS !