Valve Preamplifier (2a)
Construction (continued) and test data

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Component list
Resistors:
R1,R1´= 100?
R2,R2´,R4,R4´= 3k?9
R3,R3´= 470?
R5,R5´= 10k?
P1 = 10k? stereo potentiometer, linear, tracking
P2 = 10k? stereo potentiometer, linear, tracking
2 holders for potentiometers
Miscellaneous:
S1 = rocker switch, 2 poles, 3 contacts
Solder pins
High Voltage Supply
Resistors:
R1 = 10k?, 2W
R2 = 100?, 4.5W
R3,R4 = 1k?
R5 = 6?8, 2W
R6 = 150k?, 2W
Capacitors:
C1 = 100µF 400V, raster 10mm
C2,C3 = 22µF 400V, raster 7.5mm
Semiconductors:
T1 = BUZ92
T2 = BC546
D1,D2,D3 = zener diode 110V, 1.3W
D4 = zener diode 18V, 1.3W
Gl1 = B500C1500, rectangular case (500V piv, 1.5A peak)
Miscellaneous:
Heatsink for T1: SK 68/50 (Fischer, Dau Components)
Isolation and mounting material for T1 and heatsink
Solder pins
Headphones/Line Switch
K1 = stereo headphones socket, PCB mount
Re1,Re2 = relay, 1 changeover contact, 12V coil (Omron G6E)
R1,R2 = 680k?
Low Voltage Supply
Capacitors:
C1 = 2200µF 40V, raster 7.5mm
C2 = 100µF 40V, raster 5mm
C3,C4 = 100nF, ceramic, raster 5mm
Semiconductors:
Gl1 = B80C1500, rectangular case (80V piv, 1.5A peak)
D1 = 1N4148
IC1 = 7812
Miscellaneous:
Isolation material for IC1
Si1,Si2 = fuse, 0.2 A, slow, with PCB mount holder
Solder pins
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