31 July 2015

biNixie clock - preview video

I have finally produced a working firmware for my own implementation of a two-digit clock using two Burroughs B5092 Nixie tubes from late 1960's. The biNixie Clock. It uses
  • an Arduino clone,
  • a lumos.sk high-voltage PSU,
  • K155DI BCD decoders and
  • a DS1307 RTC for timekeeping.
It works from 12Vdc. Each tube anode has an independent variable resistor to set luminosity.

I need to complete the circuit and firmware with a couple of (hidden) buttons to set the time and a proper wooden housing.

I will release the Arduino firmware after tiding up the code.

28 July 2015

Friedrichshafen 2015 - What I bought

This is mainly a log for my future self of what I bought at Friedrichshafen HAM fair 2015:

  • WW2 headset with PTT (1€).
  • Bencher BY-2 paddle.
  • A pair of Hama gamepad USB controllers.
  • Diamond HF-20FX 20m mobile antenna.
  • Burroughs Nixie sockets (priced between 50c and 3€ each).
  • Russian VFD 7-segment IV-3 (1€ each).
  • Russian VFD 7-segment IV-6 (1€ each).
  • Russian VFD IV-1 (1€ each).
  • Nixie driver chips K155DI (equivalent of 74141, 1€ each).
  • Blank spiral mic cord (6 wires, 1€).

17 July 2015

B5094 Nixie now fully operational

The B5094 Nixie was tickling me: why only two symbols light up? Why others don't? I asked around and the hint was to increase the voltage supply (as well as the current limiting resistor).

Worth a try. My PSU module reaches 186 V: not enough to light up other symbols. Then I added in series a 12 V battery pack for a total of 198 V and ... all 3+3 symbols said "Hello!".

The series resistor was increased to 47k that is probably still too low. I need to measure the working current of that specific Nixie and make sure I do not exceed the 3.5 mA stated in the datasheet.

The need for an increased voltage is a sign that the tube is "tired". The 4th B5092 doesn't fire with 198 V. I may try to go higher but that's not too easy to achieve with batteries, or keep it as a souvenir.

09 July 2015

Friedrichshafen 2015 - What I have not bought

These are my regrets. Objects I have not bought at "Ham Radio 2015" in Friedrichshafen but I should have.

A Fluke 8050 bench multimeter (~50 €).

A Heathkit G-1 signal generator. Found under a table. Looked nice.

A strange 1960's telephone loudspeaker (1 €).

A metal box with three flanged N sockets (probably 1 €!).

An empty metal box with handle (probably 1 €1).

There were other interesting things too, mainly stuff older than me. Either too expensive for a home ornament or too big to transport in a already fully packed car.

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.