On Wednesday 05 February 2025 04:45:28 pm wn4isx via groups.io wrote:
2) Astron uses the uA723 regulator, a fine regulator even if it is 50 years old.
However Astron, like most users of the uA723 never read, or at least never understood, the original spec sheet requirements for feedback capacitor and ~1k series resistor to protect the current sense input. Leave that resistor out and you will pop a uA723 faster then you'd believe. This is based on personal experience with home made uA723 power supplies and Astrons at 2 jobs.
I last messed with the 723 somewhere in the early 1970s. I'm guessing that this was before the common 3-terminal regulator parts were pretty much everywhere. I have very little reason to consider using one these days, unless I'm missing something here. My salvage over the years has yielded me enough 7805 and 7812 parts (and lots of others) that I don't see me running out any time soon. While I suppose that there might be reasons to consider using the 723, none are coming to mind offhand.
For higher currents I have a couple of switchers on hand, one 25 or 30A, the other one 10A. Both are adjusted to 13.8V. I'm seeing that pretty many places with ham radio stuff. I'm wondering if circuits that are calling for a nominal "12V" will be bothered by that 13.8V...
For anything else, I have a whole mess of computer power supplies, both "AT" and "ATX" style, and a couple of large boxes full of wall warts, both AC and DC output and varying voltages.
3) Astron occasionally parallels silicon rectifiers.
I believe that the circuit in the referenced pdf uses two sections of a bridge rectifier. Which still doesn't mean that they're gonna be identical, but... Now I can't remember if I've ever actually seen that done in a commercial product. I don't recall any instances.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
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Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
