Schematics of Atanasoff-Berry Computer logic circuits?

Correct, but I think you've misinterpetted what I was saying. Philips/Mullard valve numbers are actually quite informative, and can be decoded as follows : First letter gives the heater/filament rating : A = 4V B = 180mA??? C = 200mA D = 1.5V E = 6.3V G = 5V (early-ish ones, later used for miscellaneous ratings) H = 12.6V? K = 2V O = Semiconductor (no heater) P = 300mA U = 100mA Y = 450mA (Where a current is given, the valve was intended for series-string operation) Subsequent letters give the electrode structure. For multi-section vales, they're given in alphabetical order A = diode B = double diode C = triode D = power/output triode E = signal tetrode F = signal pentode H = hextode/heptode K = heptode (phantom-cathode tpye of fequency changer)/octode L = power/output tetrode/pentode M = tuning indicator ('magic eye') N = thyratron (gas-filled triode/tetrode) Q = nonode X = gass-filed full-wave rectifier Y = half-wave rectifier Z = vaccume full-wave rectifier The first digit gives the base type None/1 = miscllaneous (often only a single-digit number means P side contact base) 2 = B8B 'Loctal' For 3-digit numbers, 2 = B10B 3 = International Octal 4 = B8A Rimlock 5 = B9G. For 3 digit numbers, 5 = B9D 6,7 Subminiatores 8 = B9A Noval 9 = B7G (7 pin miniatore) Other digits distinguish between valves where the rest of the code is the same. Now the oroginal poster was talking about some 12V-anode-voltage valves. He'd rememebrs are frequency changer -- a triode hexode -- with an ECHnn bumber. I beleive the full number of that valve is the ECH83. And that the EBF83, and possibly the EF83 are als 12V anode types. This has nothing to do with the the American type 83 rectifier valve -tony