In reply to MSF's message of Wed, 29 Dec 2021 18:29:56 +0000: Hi, [snip] > >What's your goal? Is it to demonstrate how simple or clever such a thing could >be or do you have a practical result in mind? Do you want this to operate as a >remote switch or merely to show a record of the bit transfer on the receiving >end?
My goal is a mailbox flag. Unfortunately they aren't used in Australia, and I can't rely on the mail delivery person to trip the flag for me when mail is delivered. My mailbox has a slot, and doesn't need to be opened to deliver mail. Therefore I need an electronic device that detects when the mail has been delivered and sends a message detectable in the house. I have already designed the detector for the mailbox itself, but the transmission is proving more thought provoking. Ideally it would result in a pop-up message on my PC. The internal part isn't a problem, as long as I can detect a signal. Sound might work, but I am working with only about 3V and maybe 30 mA at the mailbox (or 1.2V & as much current as a AAA cell will provide), so would need to design a sound generator that ran on that but still produced a sound burst strong enough to be picked up at the house, thus probably directed and focused. It also has to be weather-proof, which a normal loudspeaker wouldn't be. The 3 V is a consequence of re-using a "lawn-light" for the power supply in the mailbox. I get plenty of sunlight, and mail only rarely, so solar is a good solution for the power supply. I also have a wireless doorbell, so will see if that has enough range. If so, I could probably modify one to do the job. There are electronic "mail detectors" for sale, but most of them rely on the mailbox being opened to generate a signal. In theory I could modify one, but can't tell how easy/difficult that would be without first buying one. I did consider simply lighting a LED that could be seen from the house, but that's too difficult to see in bright sunlight, at that distance. (My mail gets delivered in the morning.) Regards, Robin van Spaandonk <mixent...@aussiebroadband.com.au>
