in the Aleph 4 is a 680pf silver mica, in the Aleph 2 there is a 1nf silver mica. Can I keep the 680pf or do I really need the 1nf? Silver mica's are overhere hard to get, that's why I ask!
Edwin
BrianGT said:
For the difference in the arrangement of the npn compensation cap (C7 on the Aleph 2), it does not matter if it goes across the collector emitter, or the collector base, as long as the correct value is used (0.001uF for collector base, and 0.01uF (labeled 103) for collector emitter). The existing setup of the Aleph 4 should be fine here.
For the connection of the 220uF (C9 in the Aleph 2), it does not really make any difference in the operation of the circuit. The majority of the Aleph schematics and the patent schematic are done the say way that the aleph 4 circuit is done. For the pcbs I made for the aleph, I kept to the way that the aleph 4 is wired. You should not need changes here.
The only real change that I forsee in the transformation from Aleph 4 to 2 would be to change the resistors near the ZTX450, which if I can remember, set up the biasing current for the current source. I am not sure what values you would want to use here.
The board layout for the Aleph 4 should work fine for the Aleph 2, with minor component changes.
