A Useless Machine with delay and howl

The useless machine or ultimate machine originates from Claude Shannon, the scientist who figured out how to find the channel capacity in a communications system. I bought the basic machine as a kit from Solarbotics.

But then I added a few features:

• A delay circuit that makes it look more alive as it gives the impression of doing some thinking before it responds to the switch.
• Sound that varies with how open the lid is and the amount of light that hits the photosensitive resistor. It was inspired by the design of the Growl and Scream Altoids of FightCube.
• A couple of LEDs, a red one when it opens and a blue one when it closes.

The circuits were built on small pieces of veroboard and the circuit diagram can be downloaded from here. In retrospect I'm not completely happy with the sound, it could have growled and screamed even more, but then how much effort can one really justify putting into a project which is - useless - anyway?

My first 24 hours on WSPR

My first beacon on 30 m, a free-running Ultimate QRSS kit (no GPS) has now been running for a full 24 hours using the Weak Signal Propagation Reporter (WSPR) mode. The figure comes from the WSPRnet page.

With an output power of about 150 mW to an 80 m horizontal loop it has not been possible to reach beyond Europe so far. Perhaps this will happen in the future with better conditions and/or with some more output power.

Added 26.9.2012: I made it for the first time across the Atlantic!
Timestamp           Call       MHz         SNR Drift  Grid      Pwr Reporter   RGrid      km      az
2012-09-26 00:50, LA3ZA, 10.140262, -26,   -2,   JO59fu, 0.2, WB2EEE, FN21xh, 5852, 290

Altoids Projects

Press image for magnification

I like to build small electronics projects and like many others I have found the small Altoids tins to be excellent enclosures. 

These tins are inexpensive, well shielded, easy to work with, and least but not least they enable you to make experimental circuits that are sturdy enough that they can be reused later.

Pictured here is a collection of projects I have built over the years with the hope that  they may inspire others.

Noisy Designer Lamp

Herstal pendant lamp,
type 06

Some years ago I had this annoying noise that made listening for weak signals on several of the shortwave radio bands virtually impossible. In the end I was finally able to track down the noise source: Our beautiful Danish Herstal designer lamps in the kitchen. Actually it wasn't the lamps themselves, but the dimmable switch mode power supply that came with them.

After some years of always having to remember to turn them off, in the end I just replaced the original noisy dimmer with a fixed voltage, noiseless, electronic transformer and inserted lower wattage 12 V light bulbs in the two lamps.

The original dimmer came in its own nice conical designer housing and inside one finds a more ordinary plastic housing. And of course it is marked with the CE mark, thus indicating that it should be fine with respect to noise.

Fixing my Lithuanian oscilloscope

I visited Riga, Latvia with a youth group which we as a family were involved with in 1992, and there I stumbled upon a Soviet oscilloscope in a department store. It was from the neighboring country, Lithuania, and was manufactured in Vilnius, the capital. The markings say what I guess means "Made in the Soviet Union". At least it says CCCP in the upper right-hand corner. I remember these letters very well as all Soviet athletes used to have them on their backs.

The oscilloscope came with full documentation, even with a bilingual manual. I had grown fond of this oscilloscope as it was lightweight and simple to use once I had learned what the Russian markings meant. It is a typical instrument for TV-repair with a 7 MHz bandwidth.

Now after 20 years, I was therefore very sad when it malfunctioned. This was the time to test if the manual was helpful or not. The symptom was that the beam no longer could span the whole screen in the X-direction. Even with the Horizontal positioning all the way to the left one could barely see the beam.

I opened the bilingual manual only to discover that the two languages were Russian and Lithuanian!

Transformerless tube power supply

In 2012 bulky power transformers that work directly from the power grid at 50/60 Hz have mostly disappeared. My objective here is to modernize the power supply for a one-tube transmitter in the same way.

The circuit is based on an electronic transformer for LED or halogen lamps. Electronic transformers usually have a minimum power rating, below which they will not start. This one can tolerate a lower load than most and gives out 12 Volts for a load from less than 10 W and up to 60 W.

Nostalgia from LA3ZA in 1949

I wasn't even born when this LA3ZA QSL-card was issued in 1949. This is because I am second generation LA3ZA after my father. When the callsign was reissued to me in 2001 it had been inactive for 40 years or so.

I still have the Hallicrafters S40A receiver which my father used with a 2 W input homemade tube transmitter. The S40A (image below) was what introduced me to shortwave listening during the good conditions of the solar peak in the late sixties, despite its mediocre performance I would say.

Vertical antenna on a turf roof

A vertical wire antenna based on a MFJ-1904H 6.7 m (22 feet) telescopic fiberglass pole as shown here is easily tuneable for all bands from 40 m to 10 m. Here it is placed on top of a turf (sod) roof with quarter wave radials for all the 7 bands going to each of the two sides sloping down as they follow the contour of the roof. The antenna seems to work satisfactorily at least on the 30, 20, and 17 m bands which I have been able to test so far.

A turf roof is a traditional Scandinavian type of green roof covered with grass. It dates back to the Viking age and before. In modern times it has seen a renaissance in e.g. mountain cabins.

But how does the turf affect the antenna or to pose the question more precisely: Can it be used to improve the ground plane and the antenna's performance?