Electronics Projects (by )

So, my electronics workbench is a mess.

This is abundantly clear in the picture from my blog post on redesigning my workspace; the awkward layout is certainly part of the problem, but a deeper problem is that I don't do many electronics projects. So this big workbench is rarely used for its intended purpose, and thus accumulates junk, and thus isn't very inviting to start projects at, which adds to the fact that I'm a bit edgy about STARTING electronics projects, and a vicious cycle has set in...

The only electronic projects I did lately were the 12 volt DC power distribution system for the van and a 9:1 impedance transformer, but those were mainly mechanical builds; the electronics were trivial.

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Insulating the Workshop Roof (by )

I work from home, in my workshop at the end of the garden. I have my rocket mass heater to warm it in the winter, but while the radiant heat from the primary heat exchanger is comfortable, as soon as the fire burns down it's freezing again, because the room's air temperature doesn't really rise.

Also, in summer, I roast in here; the sun beats straight down on the dark felt roof above, and my ceiling is just four layers of felt and a couple of centimetres of plywood, so on sunny days the wood above me reaches 40-50 degrees Celcius and roasts me with infra-red radiation.

BUT NO MORE!

Because over this past summer, I've finished insulating the roof. I did this by getting inch-thick foil-backed foam boards and fixing them between the joists, with twenty centimetres of woolly insulation above that. Here's a few photos to illustrate what I mean, taken when I tested the method at the end of last year:

First section of workshop roof insulation

Partially insulated roof

Insulation around the chimney

There's a gap of about five centimetres above the woolly stuff, to allow air to flow. A big danger of sealing a roof up with insulation is that warm, humid air from the room beneath will manage to sneak up, past the insulation, reach the cold area above, and promptly condense, making it nasty and dump up there - leading to the roof rotting. So I left an air gap, and made sure that every area of the roof was ventilated. Since the roof is punctuated by wooden beams, this meant putting an air vent at the top and bottom of each "bay". In the summer, the air rising out of the vents at the upper end of the roof was pretty hot, too, so convection of air along the underside of the hot roof also helps to get rid of heat in the summer.

Thankfully, this meant that I wasn't roasted during the summer; and now I've mainly finished running aluminium tape over all the edges, so my warm air doesn't seep up and dissappear, it's also keeping the heat much better in winter. I've been running the rocket mass heater in the mornings and the room temperature has risen and stayed up for most of the day, thanks to the residual heat from the secondary heat exchanger now being enough to replace heat lost to the outside.

Also, it seems the aluminium tape makes a good electrical contact with the aluminium backing on the foam board, so my entire ceiling is a big radio-frequency reflector, which might prove useful in keeping all the noise-leaking computers in my workshop separate from any antennas I put on the roof...

Amateur Radio Law (by )

The radio spectrum is heavily regulated worldwide. This is because some uses of radio are matters of life and death - communications between ambulances and fire engines, air traffic control, radio navigation, GPS, distress calls from ships, military operations, aircraft/shipping radar, that sort of thing. It's easy to interfere with radio services by just happening to transmit radio waves at the frequency they're using - even accidentally, by a tuning mistake or a poor-quality transmitter that leaks energy at random frequencies - so there's a bunch of laws regulating radio transmitters in every country.

Basically, they trade off various freedoms. Operating a radio transmitter can generally be done using one of three legal approaches:

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