Continuing to work on a BOM for this. Struggling a bit with the 10.000uF 25V PSU electrolytic. The PSU board looks to have 12.5mm spacing, and there is nothing at a reasonable price I can see that just plugs in.
I could not see why 25V was specified for this part - 16V should also be OK? Isn't it just less than 1.4 x 9VAC? The general purpose caps have a lowly life of 2000hrs @ 85C. I widened the range a bit, and came up with this candidate. Anyone see an issue?
EKYA160ELL123MLP1S 12.000uf 16V Chemi-con
I could not see why 25V was specified for this part - 16V should also be OK? Isn't it just less than 1.4 x 9VAC? The general purpose caps have a lowly life of 2000hrs @ 85C. I widened the range a bit, and came up with this candidate. Anyone see an issue?
EKYA160ELL123MLP1S 12.000uf 16V Chemi-con
Santa has come early and dropped off the PCBs down the chimney. Impressive service throughout, with simple confirmation of my address needed so it went to my mailbox. The boards look ace too! Time to press the 'go to checkout' button on my Mouser project list and get the missing parts. I will order in two tranches so I get free delivery each time, and have time to remember the bits I should have ordered :-/
Thankyou @snapper for facilitating everything! You have opened my eyes to the power of these PCB solutions.
Thankyou @snapper for facilitating everything! You have opened my eyes to the power of these PCB solutions.
I repeat it here as a precaution for all those who ordered the boards of the first version:
now, to my regret, i have discovered an error on the powerboard: the soldering eye of the resistor next to the 9v terminal block must be separated on both sides from the ground see pictures. This is best done with a sharp cutter knife, then measure again with a multimeter to be on the safe side!
sorry
now, to my regret, i have discovered an error on the powerboard: the soldering eye of the resistor next to the 9v terminal block must be separated on both sides from the ground see pictures. This is best done with a sharp cutter knife, then measure again with a multimeter to be on the safe side!
sorry
back to the topic of power supply: if you use an r-core transformer and switch the 6.3VAC windings in series to 12.6VAC, the LM338 series controller will probably get pretty hot at work. It doesn't bother the transformer, I loaded it with 800mA for a long time. I would prefer an adjustable step-down switching regulator here, as I have seen in the forum with the baby-huey amplifier. My question would be whether I should put an additional LC filter behind it, there is still space on the board? (I'll probably make a new board for myself)
what i have found are complete preamplifier power supplies that make a separate power transformer completely superfluous.
https://www.ebay.com/itm/195500527259
https://aliexpress.com/item/1005003365085395.html
https://aliexpress.com/item/1005001814771782.html
https://aliexpress.com/item/1005004463301307.html (only 260V out!)
what i have found are complete preamplifier power supplies that make a separate power transformer completely superfluous.
https://www.ebay.com/itm/195500527259
https://aliexpress.com/item/1005003365085395.html
https://aliexpress.com/item/1005001814771782.html
https://aliexpress.com/item/1005004463301307.html (only 260V out!)
another solution for the problem with the ground soldering eye of the 1K5 resistor (the traces are very small that by welding you risk restoring the connection): drill out the soldering eye (approx. 3mm), cover one resistance wire with insulating tube and solder it to the rectifier or terminal block from the bottom side, in my opinion a "clean" solution 
