Transistor Vibrato for Guitar Amplifier, in: Radio Electronics, May 1963
Posted: 11 Apr 2022, 23:39
AMPLIFICATEUR GUITARE 5 W (ECC83, ELL80, EZ80), BF REALISATIONS (p. 46 dans Le Haut parleur n° 1061 mars 1963)
But it's sadly not available digitally, as far as I can tell.