[GreenKeys] Are my mails getting through?

[drlegendre .]

I sent the following text yesterday, and surprisingly, it met no reply.
Another member says it never showed up in his inbox.

Did it make it to the list?

-----ORIGINAL TEXT FOLLOWS----

Howdy Gents,

I'm just completing a scratch-build of an RS-232 / 60mA CL converter device
as described on this page: http://www.aetherltd.com/connecting.html

What is the purpose of the Keyboard Loopback terminals (pins 3 & 4) on
connector J1?

Pin 4 is a copy of the KB output signal on Pin 5, and Pin 3 is tied
directly to the 120V DC supply, just downstream of the 2K 10W
current-limiting resistor.

As I see it, when the converter is connected, but idle, the current loop
will be closed which would pull both Pins 3 & 4 down to roughly 3.3V DC
above ground. This is assuming a 55R selector coil. When the loop opens,
Pin 3 will rise to the nominal 120V DC supply, and Pin 4 will.. I don't
know.. float? Show some high-Z voltage?

So what's it all about, anyway? As ever, thanks in advance - your help is
much appreciated.

BTW - I used a very cheap & common 28V AC control transformer for the 120V
DC supply. Running a standard voltage +tripler+ gives me almost exactly 120
DC with (what seems to be) very acceptable ripple at 60mA. I used 3X 1000uF
@ 200V caps, but I'm sure it could be executed with caps of lesser value
(and voltage as well). In fact, the ESR of the large caps may actually be a
detriment to the tripler circuit - eh?

-Bill
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