Ella: a power amplifier, all purity, cost of realization = 5 CD, it lends to test 4 different versions all with their personality, little watt but exceptional sound. This is that most elementary one, its particularitity resides in the perfect compatibility between the anodic current of ecc83 and a current of rest of the BU508, therefore to allow the directed connection, without no stabilization of the job point, is sufficient the resistance from 18 Ohm on the emitter for one perfect stability of the gain in function of the temperature.
The coupled transformer of escape being to a transistor, is a lot little critical, can usefully be used a common transformer, - trasf- 160 coils d=0.7mm, 2800 coils d=0.25mm, 160 coils d=0.7mm nucleus to double quantity C type U38, the two windings of secondary (the out) by 160 coils go connected in parallel, are not previewed feedback, transformer of feeding: Pn=80va, v1=220v v2=200v 0.3Ä, v3=6.3v 1A, - v2 it is the common anodic feeding to both channels, that it goes at least straightened with a bridge 800v 1A and filtered with at least 100 mF, v3 is the feeding of the filament that does not go straightened, to connect a resistance from 4,7 K between filament and massa. The power that is obtained is of various W, attends W well not tens of W.
One sketch of the piece of furniture with the measures click here
This is simple varying, but to try.
c1=1mF 63v c2=3300mF 16v c3=4700mF 16v c4=33mF 350v R1=150K 1w R2=1,2K1/2w R3 is the feedback, optional, to try leaving from 100K R4=60 Ohm1w R5=100 Ohm 1w R6=10K1w - D1 = 1N4007- trasf1 interstage trasf2 160 coils d=0.7mm, 2800 coils d=0.25mm, 160 coils d=0.7mm 800 coils d=0.125mm nucleus to double quantity C type U38, i two windings of secondary (the OUTPUT) of 160 coils goes connected in parallel, the 800 coils is the optional feedback, transformer of feeding: Pn=80va, v1=220v v2=200v 0.3 A, v3=6.3v 1A, v4=5v 0.À v5=5v 0.À - v2 is the anodic feeding, v3 is the feeding of the filament, v4 and v5 they are the polarizations of the two channels, go opportunely processed with a bridge of diods and very leaked, possibly stabilized p. es. with two stabilizers 7805, or more better reglaging the tension to 4.5v with opportune resistances.
mod Ella by Alessandro Coppi
Good job by Alessandro Coppi