Re: The joy of FORTRAN

On 3/13/25 12:30 AM, rbowman wrote:

On Wed, 12 Mar 2025 22:50:23 -0400, c186282 wrote:
 

    AH ! Solar-powered pocket calculators ! They have a very small thin
    PV strip, can power an LCD calc even in room-level light. SOME
    surplus place has a bunch of those !!! More Google fun ! May even
    have some in my old-junk boxes .......

 There you go...  I've got a couple that the VFW was sending out with their
begging letters. They work better than my old RatShack in room light.
Considering the source the whole thing must be dirt cheap. I liked it
better when they sent calendars. I had to actually buy one this year.

   Some org always donates a calendar to me ... or
   six, or ten ............ along with the 'send us
   money' form  :-) That's old human psych, offer a
   tiny 'gift' then, morally, you're obligated to
   give the sender a much larger return.
   Anyway, those calculator PVs sound Good Enough
   for what I want to do. Small, very thin, enough
   power, easy to conceal. Just gotta dig around.
   Dip 'em ... first in epoxy and then in clear silicone.
   That oughtta hold up for many years. Stick it to the
   top inside surface of the box ... basically invisible
   to the postman.
   The delta detector - simple. Maybe a 100-500k resistor
   shorting the PV cell - plus a small CAP. SLOW small
   changes, the resistor will bleed off the charge. Faster
   change, the resistor won't cope and you'll get a pulse
   through the cap - enough to trigger an activation
   switch on the transmitter board. An FET wired to
   self-latch will do it. When the supercaps die, the
   whole thing resets.
   All coming into focus .......