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Back in the days of the Berlin Wall, these Nixie tubes were manufactured by a now long-forgotten company. Fast forward to the twenty-first century, and Hans Summers found them stocked by an antique electronics part company. Originally painted red, the coating from the 4-inch high tubes were painstakingly removed using a craft knife. Using a plain matrix board and wire connections, Hans built the circuit on three boards.
The first holds the rectifier, divide by 50 circuit, seconds counters and seconds driver transistors. The second and third boards hold the counters and drivers for the minutes and hours digit pairs. Now your tribute to East Germany is sure to get past Checkpoint Charlie.
You can read the full details of the project, including a data sheet for the Z568M and details of the construction, on Hans' website.
The Nixie tube
Hans used the Z568M, which is 4-inches high (100mm) and has a digit height of 2 inches (50mm). It is therefore truly a giant amongst nixie tubes, he says, presumably intended for railway clock applications and so on.
It is painted red to improve the contrast. There is also a non-coated version available, the Z5680M, but he could not obtain any at that time. Hans writes that because he finds the internal construction of nixies very beautiful, he removed the paint using a craft knife. It was a long and tedious process during which I was constantly afraid of breaking the tubes, particularly when excavating the seal at the top of the tube.
Construction
Hans writes: I did not use a printed circuit board (PCB), instead I used my favourite method of construction, which is plain matrix board and wire connections. The circuit is built on three circuit boards. The first holds the rectifier, divide by 50 circuit, seconds counters and seconds driver transistors. The second and third boards hold the counters and drivers for the minutes and hours digit pairs.
The nixies are mounted in pairs on single-sided PCB material. I placed the copper side upwards, and drilled holes to match the nixie base. The nixie pins are pushed through the holes and soldered to wires on the underside. It is probably better to use sockets for the nixies but the Z568M is a very large nixie for which I doubt ordinary sockets are available. It is possible to build your own sockets but I opted for direct soldering, though this must be done with extreme care not to crack the glass. The central nixie pair (minutes) has two PCB-material pillars which the colon neons are attached to, with their 100K series resistors. The circuit board for each pair is attached behind the nixie tubes at right angles to the nixie boards, using triangular cuts of PCB material.Circuit
"I used a very similar circuit to Mike's nixie clock (http://www.electricstuff.co.uk/), writes Hans. "Mine is a 6-digit clock, i.e. has an extra pair of nixies for the seconds. I made a few very minor modifications to the circuit.
"I moved the seconds hold switch to earlier in the counter chain, because I found that otherwise a full second did not elapse between letting go of the switch and the seconds being incremented. Since my clock display seconds, I also connected the colon nixies to be on continuously.
"I omitted any form of mains isolation, in the interests of living dangerously (do this at your own risk!). I found a series resistance of 22K to be about right for the Z568M, but they overheated so I replaced them with two 47K resistors in parallel (23.5K).
"The total cost of the electronic parts for this circuit (excluding the nixies) was under UK £10. Of course, the nixies are very expensive, and the materials for the cabinet."
View a full size circuit diagram (1188 x 873, 95K)
Parts List
- 6x NIXIE tubes from eBay or similar
- 4x Neon bulb
- 8x 4017 integrated circuit
- 1x 4013 integrated circuit
- 44x MPSA42
- 1x 5.1V zener diode
- 5x 1N4004 diode
- 44x 33K resistor
- 12x 47K resistor
- 7x 100K resistor
- 1x 2.2M resistor
- 2x 10K resistor
- 1x 68K resistor
- 1x 470uF capacitor
- 1x 100nF capacitor
- 3x 1nF capacitor
- 1x 100pF capacitor
- 3x reed switch
- 1x bar magnet
- 1x isolating transformer
Nixie history
For more background on Nixie clocks, including the history of Nixie tubes, see NixieClock.net
"Nixie tubes were originally developed in 1952 by the Haydu brothers for the Burroughs Corporation..."
Comments (3)
Yes I remember Nixe tubes, in fact I still have a home made frequency counter using four such tubes. They have clear glass so that the internal anodes shaped in the form of the digits 0-10 can be seen. I built it 30 odd years ago when only simple ICs were available, and no LCDs or even LEDs. One forgets how rapidly technology advances.
Posted by Ian Cooper | July 23, 2008 11:11 AM
Posted on July 23, 2008 11:11
I feel that using integrated circuits in this project in an anachronism. For true authenticity the logic should be made from discrete components. It should not need more tham 100 transistors :-)
Posted by dave brown | July 25, 2008 10:56 AM
Posted on July 25, 2008 10:56
You dont even need transistors. Simple ring counters made with neon tubes (trigger tubes are more reliable) to divide down the mains frequency to derive a timebase will do. Throw in a valve rectifer stage for the nixie HV and its about as simple as a clock can get.
Posted by Bill | September 3, 2008 11:56 AM
Posted on September 3, 2008 11:56