Category: Electronics

The Polyp Mixer (by )

So, on my desk I often have a desktop computer and a laptop. I've got a decent HDMI/USB KVM switch so I can flip my big monitor, keyboard and mouse between the two, and that's great.

However, I also have a hi-fi amplifier and speakers for audio output. This is hooked up to the desktop PC, and has selectable inputs, one of which is connected to a lead for the laptop - but I rarely plug the laptop in. This is because I can only select one input on the amplifier; and although I'm usually only listening to media from one device, I want to be able to hear notification pings from either. So I tend to leave the laptop on its own nasty little speakers and only have nice audio from the desktop PC.

Clearly, this sucks. Many years ago I had a cheapo mixing console that sat on my desk, with my CD player, minidisc player, and PC connected to the inputs, outputting into my amplifier; it was cool to be able to just hit play on anything and hear the result through my good speakers, and having all those knobs and sliders to play with was definitely gratifying. However, it was bulky, full of useless-to-me features like phono inputs and cross faders, and eventually died a death from being left switched on all the time.

Plus, I'd recently resolved to do more electronics, so there was only one thing to do: Make a mixer.

The Polyp Mixer

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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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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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Pictures from Space (by )

So the International Space Station (ISS) contains some equipment that's part of a project called ARISS, or Amateur Radio on the ISS.

One of the ARISS projects is occasional transmissions of images via SSTV, or Slow-scan television - basically colour faxes sent via radio.

Anyway, a few days ago, I saw that there was an SSTV transmission scheduled, and the ISS would be passing over England at times I would be able to try and pick it up, so I gave it a go... Read more »

A keyboard design (by )

Ok, so a friend of mine is making himself a custom keyboard - there's a whole hobbyist community of people who design their own, often based on a published design like the Ergodox.

This is related to something I've long wanted to do, which is to obtain myself a chorded keyboard. So I thought I'd write up my current thoughts on the matter, given that they've been brought to the forefront of my mind again!

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