Re: The joy of FORTRAN

On 3/9/25 3:40 PM, rbowman wrote:

On Sun, 9 Mar 2025 04:55:42 -0400, c186282 wrote:
 

    Came across old diagrams - Quaker-Oats round boxes wrapped to form
    the antenna transformer/inductor, galena crystals, sharpened point
    contact you had to tweak around by hand looking for the 'sweet spot'.

 My uncle had one he'd built as a kid, probably c. 1915, with the crystal
and cat whisker. By my time you used a 1N34, which took all the fun out of
it.
 I spent a winter in AZ working my way through radio history. iirc it was a
ARRL publication on vintage radios. It's interesting what you can build
from junk laying around in the desert. Old shotgun shells make nice coil
forms and if you punch out the primer you have a handy way to screw them
to your breadboard. There was a RadioShack/Sears/Music store in Ajo for a
few 20th century components.

   There are some older US and Brit military comms
   manuals too - more practice than theory - that
   will tell you how to build a crude transmitter,
   maybe receiver, from 'junk'.
   For a long time, the only electronics place was
   a "Lafayette" - albeit 15 miles away in the
   next town. The corp still exists, but it's
   online-orders only :
   https://www.lafayetteelectronicsupply.com/
   Looking at building a small FM transmitter wired
   to my mail-box. Being right at the road, and a bit
   away, it's useless trying to do image-ID and there
   is no hope of getting power out there.
   SO ... like a 2-transistor FM transmitter, old
   school, tuned for like the very top or bottom of
   the commercial FM band. Amorphous solar cell
   stuck under the box, inobvious or the punks will
   get at it. Photocell to one of the vent holes in
   the bottom of the box. Power - NOT batteries, but
   instead a few super-caps, charged by the solar.
   Open box, big sharp pulse of light triggers the
   thing. Super-caps run it for a couple of seconds,
   1000hz tone. Just need a dirt cheap FM radio always
   tuned properly indoors. The caps running down
   effectively reset the transmitter.
   I've seen commercial devices - surprisingly expensive
   and/or bulky. 400mhz mostly and no solar charging.
   Just gotta find the easiest way to make that 'light pulse'
   detector/trigger. Some days are bright, some are not, so
   raw illumination level isn't what we want - but a RAPID
   CHANGE instead. The other trick would be to rig a tiny
   switch that triggers when the door opens, but the
   design of the box makes that a tad awkward, the bottom
   of the door never dips below the frame level. Can't
   have obvious weird wiring or the postal guy will think
   it's wired to GET him  :-)