Re: The joy of FORTRAN

On 3/10/25 11:37 AM, Sn!pe wrote:

rbowman <bowman@montana.com> wrote:
 

    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.
>

>
Just for an alert? How far? I'd probably use a couple of Picos or even
Arduinos with nrf@$L01 modules.
>
https://howtomechatronics.com/tutorials/arduino/arduino-wireless-
communication-nrf24l01-tutorial/
>
and a PIR to detect when the box was opened.
>

 PMFJI.
 A reed switch with a small permanent magnet attached to the door to
actuate it can do the detection very simply, cheaply and unobtrusively.
 <https://en.wikipedia.org/wiki/Reed_switch>
 In this instance, old tech can be best.

   A (very small) reed switch is probably the easiest
   solution.
   Trips a latch on the transmitter board and that runs
   until the supercaps go dry. Only need a few secs.
   DO own some quite small samarium magnets. Better
   for outdoor use.
   The PV solution WOULD be nice ... and I did figure
   out how to do the delta value thing simply ... but
   some old PV devices I remember from the 60s just
   don't exist anymore. Those were 1/4" screw-ins
   with a few *TINY* PV chips ... 0-5v. Very low MA,
   but that's not relevant. No such thing anymore.
   Searched on 'sensors' extensively.
   As noted elsewhere, the wiring CAN'T be in any way
   obvious or else the postman will worry the box has
   been rigged to explode. The PV solution into one
   of the underside vent holes WAS most inobvious.
   Considered using the box as part of an RC resonance
   circuit ... but RAIN would screw that up.

>
https://learn.adafruit.com/pir-passive-infrared-proximity-motion-sensor/
using-a-pir-w-arduino
>
The receiver in the how could blink LEDs, buzz, or whatever. For real sex
you could use neopixels for a pulsating rainbow effect.

   No rainbows ! Nothing obvious ! Just a clean FM tone
   for a few secs. Maybe 50-100mw would do. A few
   transistors, soda-straw inductor/transformer ....

https://www.adafruit.com/category/168