29 June 2015

1000 km round-trip

Walk for seven hours.
Smell of bakelite.
Dusty hands.
Smell of dusty bakelite.
Curious objects.
An horizontal Tower of Babel.
Refrain from compulsive shopping.
Smell of not-so-healthy food.
Look for old-time friends.
Regrets (I should have bought that, that and that!).
One thousand kilometres round-trip.

That was my first visit at the largest European HAM fair in Friedrichshafen 2015.

I joined a local group of HAMs which included the person that about 30 years ago introduced me into the world of CB.

19 June 2015

IoT thermometer online again

The newer firmware I compiled a couple of night ago did not work. The old firmware, compiled with the latest Arduino-ESP8266 combo, did not work either!

So, the problem lies either in the 1.6.4 combo or the OneWire.h library. Or both.

I can't speak for 1.6.4 vs 1.6.1, except that the resulting binary firmware is larger with the latest GUI version. 46% vs 36%, that's a lot, but I should check the actual value in bytes.

Then OneWire.h library was modified to use the internal pull-up resistor in the ESP8266 microcontroller. I think that is quite wrong since the 1wire specification calls for a 4k7 pull-up resistor while nobody really knows the internal R value, that can vary in the future too. Moreover the new pinMode setting breaks existing implementations - like mine - that diligently used the external resistor.

I reverter to the 1.6.1 compiler and the original 1wire library, with the result that my newer firmware compiles, it is small, and it works.

I added a second loop counter to distinguish between counts from power-up and counts since the last TCP o WiFi failure.

17 June 2015

IoT thermometer offiline

I did few changes to my IoT thermometer firmware (ESP8266 + Arduino IDE) and something broke: it does not read the DS18B20 anymore. I tried two 18B20: their address is read, which confirms they work and are connected properly, but temperature data is never returned.

Throughout the month since I changed the firmware I updated the Arduino IDE, the ESP8266 libraries and did a Windows update too. Too much to debug in a single night.

As a result my ThingSpeak thermometer is offline.

16 June 2015

10k online samples - reset

All was OK, and overnight my DS18B20+ESP8266 online thermometer recorded the 10'000th uninterrupted sample.

But this morning at 11h35 after 10'435 cycles the counter variable was reset. Another reset occurred at 13h50. Either AC power, WiFi or xDSL line were disconnected, or several of them together.

The firmware needs new features that help keeping track remotely of failure reasons. Back to coding, then!

15 June 2015

10k online samples

If all goes well, my ESP8266-based online thermometer will reach ten thousand uninterrupted samples in the next hours. That's a bit more than 6 days. Actually it survived a xDSL outage, and the counter was reset (memo: keep two counters). Nothing to be really proud of, but it somehow proves that the code produced by the ESP-Arduino IDE is stable enough for a long-term project.

09 June 2015

DIY socket idea for Burroughs Nixie B5092 (13 pin) - part 1

I am gathering parts for my Nixies at a rather constant pace. Unfortunately proper sockets are not easy to source these days (at a decent price). The person that sold me my Nixies had no sockets for them. So I looked up online pictures for DIY Nixie sockets and a new idea sprang up.

Several sources point out that the old serial and parallel DB9/DB25 female connectors can donate sockets whose inner diameter matches the one on B5092 pins. Glad that I kept them aside for you-never-know-when! Taking these apart in a clean way is an art itself, but I got there too.

Now I needed a way to mount all those pins (11 for each Nixie).

First idea was to get a socket 3D printed or laser cut, and insert pins in there. I have not found online a model to use, so I would have to design my own and perhaps do few reprints: more expensive than the rare surplus sockets.

On a second thought I opted for etching my own socket. Here's how.

Basically I used the way I built adapters to solder inside MiniDIN8 plugs and my Solder Paddle morse key. Take a piece of unetched copper clad board: that is our conductive sheet on which we will draw insulation segments. Sit the Nixie on the copper and mark the position of each pin with a permanent marker. Burroughs B5092 have 13 + 1 missing = 14 equidistant pin locations.

Now draw lines that join couples of opposite pins inside the rectangle that will be the Nixie base.

Time to etch. Use a heavy cutter and a helping ruler to cut along previously drawn lines. Remember PCB material releases volatile dust: use skin, eyes and breath safety tools! Also take precautions not to get hurt or damage anything around you in the process (like your workshop table).

With an ohmmeter check all 14 slices are insulated. If they are not just pass the cutter few more times.

There you are a 14-slices base for your socket.

To be continued.

05 June 2015

My first Nixie light

With the Lumos PSU kit I was able to test my Nixies in less than an hour (the time needed to build the voltage upconverter). Here she is:

Out of 5 Nixies purchased, three B5092 work. One B5092 is dead and the B5094 only lights up "u" ("micro") and "A" symbols.

Still, I am impressed they do work 46 years after the manufacture date!

03 June 2015

Voltage supply for Nxie tubes

Now that I own four B5092 and one B5094 Nixies I have to turn them on. Datasheet (a scan of) can be found on Internet, together with a wealth of information on these displays. Anyway, as I understand it, it is pretty simple: 170 Vdc and a series resistor (10k in case of B5092) on the anode. The current is less than 3 mA per filament switched on.

Either use a stack of batteries or a DC-DC upconverter. Plenty of projects online for DC-DC step-up converters. But ... I have also found a kit from Slovakia for less than 12€, designed just for Nixies and alike.

In four days it came to my door, even with a real stamp on the envelope! Yes, I used to collect stamps. Top quality PCB and components. Clear instructions in real English language. Assembly should take less than an hour to everyone.

So far I am a satisfied customer of www.lumos.sk kit.

01 June 2015

From the past: nixie tubes!

Some blogs I follow sometimes write about Nixie tubes. Those authors are enthusiastic enough to spark some interest in me. I checked usual online sources and prices are way too high for my curiosity.

Then at the local HAM flea market in May 2015 my friend Angelo spotted a box with few Nixies on a table full of valves. I explained my interest in trying out the technology and few minutes later I walked away with four Burroughs B5092 and one B5094 (we thought they were all 5092's). I wanted just one but the price was just too good to be true (two cappuccino's).

No warranty whatsoever, of course. Nevertheless they look cute, don't they?

When I told this story on the local repeater on Monday morning I learned that Nixie tubes in Italian language are referred to as a female noun. So now I've got to light up five little ladies.