Friday, April 24, 2015
Necessity is the mother...
As it happens, the kid boats were are currently with are both Italian families! One is the boat "Kiribati" with Marco and Deborah, and their son Nicolas. In an amazing coincidence, Nicolas was born the exact same day as Tessa, and we are planning a joint 3rd-birthday party in a few days, on 28 April. The other boat is "Flamenco", with Filippo and Jasmine, and their kids Mathilde and Oliver.
We are again out of cell phone range, and therefore no internet. It's a bit weird to not have that connection to the world that we have all become so accustomed to. I've realized that, in the past, almost every evening I would spend some time looking at stuff on the web.
But we still have our wonderful SSB radio that allows us to get simple emails, weather info, talk to people hundreds of miles away. We can even use it to make this blog post, but with only very limited pictures (sorry, no pictures of Tessa and the other kids, or any other normal pictures ... this time I am trying a simple diagram to see if that works).
One ever-present hassle with the SSB radio is that some of the electrical equipment on board interferes with the radio signals, causing static or weird chirps and hums. One of the offending items is our refrigeration system. I have to resort to flipping off the circuit breaker for the fridge when I want to use the radio. As you can imagine, I am less than perfect in remembering to turn the thing back on when I'm done with the radio. I've tried setting a timer to remind me, and Jolanda even resorted to putting post-it notes all over the place! Finally, after thawing all of our frozen food one time too many, I decided to take an engineering approach to resolving the problem.
[By the way, in case you are wondering -- a radio expert in San Diego convinced me that it's basically impossible to install EMI filters to eliminate RF noise caused by refrigeration systems. He advised to give up on that battle and just turn the thing off when using the radio!]
What I wanted to make was a gizmo that would monitor the refrigeration circuit. If it saw that the power was off for more than 20 minutes or so, it would sound and alarm. After looking through the various electronic parts I have on board, I came up with a pretty simple circuit, shown in the diagram. I won't bore you all with describing it in detail (anyone really interested can read the notes on the diagram). It took a couple of evenings to put the thing together. But it was well worth the effort... it has already saved my butt half a dozen times, avoiding a total melt-down of our frozen stuff! When I hear a strange "beep ... beep ... beep" I suddenly remember "Oh crap, I forgot to turn the fridge on again!".