Electronics Projects (by alaric)

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 alaric)

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:

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...

Debugging poor home wifi at the Snell-Pym residence (by alaric)

So, we have a fairly complicated network at home - the Snell-Pym Family Mainframe has a dedicated DSL link with a static IP for hosting various Internet-facing things, as well as providing internal services to the home LAN. The home LAN has the usual mix of desktop computers, the laser printer, and two wireless APs for mobile devices to connect to - one in the house and one in the workshop, because one can't get a good signal to both locations. And there's a separate infrastructure LAN for systems control and monitoring.

Now, we've often had on-and-off poor connectivity on the wifi in the house; this used to happen sporadically, usually for around a day, then just get better. The wifi signal strength would remain good, but packet loss was high (10-20%) so stuff just didn't work very well. TCP is poor at high packet loss; it's OK once a connection is open, but packet loss during the initial SYN/SYNACK/ACK handshake causes it to take a long time to retry on most implementations.

I went looking for interfering networks (we live in a pretty wifi-dense urban area) using an app called "Wifi Analyzer" on my Android phone, and it showed a strange network, always on the same channel as the house wifi (as in, if I changed the channel, it would move too). The network never had a name, and the signal strength was about the same as the house wifi; sometimes a bit stronger, sometimes a bit weaker. Read more »

Redesigning my workspace (by alaric)

So, I work from home - and a lot of my hobbies involve sitting at the same desk, as they're computer-based or electronics-based. My workspace is an outbuilding at the end of my garden, with power and Ethernet connecting it to the house. Half of it is a workshop, and the other half is my computer / electronics lab. The workshop end is pretty good since I made my custom welding bench, but the lab end was just made from furniture I had lying around that fitted in, so has been a compromise for some time. I am forming a plan to fix it!

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The effect of the pandemic on my mental health (by alaric)

I'm definitely not alone in finding the current pandemic a time for difficult emotions, but it's taken me a while to unpick the emotions I've been having. Having managed this, however, I'm documenting them here - as a record for myself, to save me repeating myself when explaining them to people who ask how I'm feeling, and in the hope that it might provide some ideas for people who are still trying to work their feelings out; you might have something in common with me.

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