On Wed, Jul 19, 2017 at 07:36 am, YT5AAA wrote:
So, following the "low cost yet functional" approach, I'd still opt for a simple resistor.
I'd agree. I've been working 'from the junkbox'. I junked a small PC power supply, and from that recovered a couple of 10uF/50V electro caps, plus resistors;10 ohm and 27 ohm (see footnote). I put the 10uF caps at the 7805, beside that blue pot, centre leg negative, one to each of the others. Either resistor feeding the board gave significant reduction of click, but still not totally clean. I did a bit more extraction from the PSU PCB, and this yielded a 220uF/16V. I took the 10u's off, looked up the spec sheet of the 7805 to find which pin was 'In' and put the 220u where the 10u was (they were both about the same size). Voila! No clicks, stable tuning!
My take: A decent reservoir cap and let the regulator do its job. Then a reasonable time-constant by resistor to keep the cap charged. In my case, 220uF*10e=22ms (45Hz). Bingo!Whatever floats your boat for the resistor, just leave a few volts 'overhead' for the regulator, and most of the heat will dissipate in the resistor, which could be placed anywhere in the Raduiono's DC+ line.
* I really miss that omega symbol from a convenient key! My hp keyboard has TWO backslash/pipe keys, and I run linux where backslash is a rarity (world please note:"forward slash" is tautological - "slash"? is by overwhelming use on the Internet "forward" by default! "Backslash" is a relic of Microsloth's DOS heritage. And TV Ad-men: the time taken by that useless word can be put to better use, surely?) - can I re-define the rogue? I've been thinking of disconnecting the one just left of "Z" and bridging with a copy of the rignt-hand Shift key cap), but on second thoughts an omega/Pi key would be a boon to the electronics industry. What say, hp?
