Well, the boards and The 4 matched fets are 200. The board, which Wayne posted a link to, shows all the parts except a resistor and a cap whose value isnt stated. Just go to your favorite supplier and get prices for every thing but the supplied fets, and double it and add to the original 200. Oh, and a transformer of some sort.
Russellc
The critical ones are the four paralled at the input. Four paralled to lower noise.
If you use LM7824 then the MAX is 40V. The 78xx drop out voltage is ~2V, so anything above 26V is OK. Need some room for AC line variation, so nominally 30V is about right. I plan to use 24V transformer, which will get me ~ 32VDC into the regs.
oooh, and it's teflon dialectric...
expected air, never thought about trimmer caps...
I suppose only 4 need to be matched. I dont know which ones, but I suspect its the two that are facing each other. ( 2 on each board) I'll have to wait for the article before I can build, but am anxious to start!
Russellc
That flew over my head, (which isnt saying much with the knowledge base around here) could you explain this teflon coated wire being used as a cap?
Thanks,
Russellc
Just twist two pieces of wire and cut them off for the desired capacitance value(for which you'll need a capacitance measuring thinges)
PTFE trimmer caps have gotten harder to obtain, i buy that stuff in every available value for two bits to two quarters overhere, but regular suppliers usually have only high value types left.
High pF versions can be modified to a lower value by someone handy enough.
Philips BC also made pretty plastic covers for these things, for protection against ambient agents, but even harder to find by the average Joe.
I suppose only 4 need to be matched. I dont know which ones, but I suspect its the two that are facing each other. ( 2 on each board) I'll have to wait for the article before I can build, but am anxious to start!
Russellc
Each board requires four matched 2SK370 jfets at the input.
See post #322 for schematic.
Attachments
Last edited:
Will this work for the 5pf cap. I know its mica but the tolerance is +- .5pf
Digi-Key - 338-1073-ND (Manufacturer - CD5CC050D03)
Digi-Key - 338-1073-ND (Manufacturer - CD5CC050D03)
Just one of these per board? Total of two needed? Newark told me they have no "minimum order" I'mm thinking of snagging these. Maybe I should wait for the article and suggestions?
russellc
The one's I have around are 1%.
I've heard good things about the sounds of both for smaller capacitance.