412
Item nr.


Gerard Telbuis Clock

Digital tube clock


Data for Gerard Telbuis
ProductionThe Netherlands, 2015.
Price was €39.
TubesDisplay tubes IV-11 (4x), IV-15.
Semi-
conductors
BC337, Diodes 1N60, 1N4007, 1N5819, 4 red LEDs, ICs LM7805 (voltage regulator), MC34063A (DC conv.), KP145NK1911 (clock processor).
CabinetWood. Size 168x90x90mm (PCB: 79x158mm). Weight 310gr (PCB: 160gr).
PowerDC 9-15V, 200mA; adapter takes 2.2W.
DocumentsBuilding instructions.

The Design

The Russian Nixie tubes IV-11 for digits, and IV-15 for the dot, were produced until far into the nineties, and are still available abundantly. My tubes have date code July 1993.

The internet has many designs with these tubes with the Russian clock IC KP145NK1911. This IC combines the clock logic with the control of the tube segments. This clock was designed and sold as a kit by Erik. I bought the kit in November 2014 and assembled it in September 2015.

Despite their modern appearance, the Russian Nixie tubes really feature classical technology. They are real vacuum tubes, complete with filaments (taking 100mA at 5.3V combined), grid and plate. The illumination effect comes from the same principle as applied in tuning eyes.


Obtained9/2015 from Erik.
Condition9.
Sound samplePLAY SOUND   The clock operates completely silently, but the radiation of the processor can be picked up by an AM receiver. You hear two sounds, namely bleeping at 00:00 and at 00:01. With some exercise, it might even be possible to hear what time it is!

This Object

Unpack the kit, check that all the parts are there, and let the construction begin! The instructions are quite clear about what you have to do.

You solder all resistors, caps, and diodes in place, and then it's time for a test. I should measure 5.3V over C7, but I don't! It turns out that the pins of IC1 touch the cooling body, causing a short. So I isolate the cooling plate with some tape and then the test runs fine.

Then the Nixies must be placed, and I found it quite hard to push all leads through the ten holes simultaneously, because they are rather stiff. So I shortened the leads to have all different lengths, and then you only have to align one lead with a hole at a time. I also found the IC difficult to place and indeed, at first the clock didn't work because I had folded one of the pins. Fortunately I could repair that, and at 20:22 on September 7, I had my clock working.

I fixed a box from board on September 11.


Part of Gerard's Radio Corner.
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