IN-1 / LC-516
Nixie Clock Project
last update, and finished: September-23-2005


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This project was based on the circuit I used in my first IN-18 clock.
If you don't know it, you can find it

What I had in mind when I starded project was:

You find all technical data of this tube HERE!!!

Pinout/ Drawing:

You find all technical data of this tube HERE!!!


Technical Data- Overview:

Röhrendaten/ Tube Data
German English      
Typ Type   IN-1 LC-516
Hersteller Brand   Reflector/ Sovtek Dolam
Vergleichstypen Substitudes   - -
Ansicht View   kopfseitig/ end-view kopfseitig/ end-view
Symbole Displayed Symbols   0-9 0-9
Symbolhöhe Symbol Height mm 18 15.5
Durchmesser Diameter mm 35 35
Höhe gesamt Total Height mm 65 65
Pindurchmesser Pin Diameter mm 2.36 2.36
min. Betriebsspannung min. Supply Voltage V 170 170
typ. Brennspannung typ. maintaining Voltage V 133 124
Betriebs- Kathodenstrom Typical Cahthode Current mA 2.5 2
Sockel Base   U11 U11
Fassung Socket   U11 oder Einlötbuchsen 2.36mm/ U11 or Pin Receptacles 2.36mm U11 oder Einlötbuchsen 2.36mm/ U11 or Pin Receptacles 2.36mm

The Schematic
Click on the image to enlarge!

Lower left you can can see the switch mode power supply, which is powered by a 12VDC/1A power supply.
I used the very common
MC34063A switching regulator. The power supply generates the 170VDV plate voltage for the Nixies.
Beneath on the right you see the Atmega 8515. It contains the software and manages all jobs in the clock.

For this clock I used the Dallas RTC DS1302. This Real Time Clock has an external crystal. The accuracy of the clock depends to the accuracy of this crystal. The RTC is puffered by a Lithium Battery which lasts more than 10 years. The Time and Date will be stored when no power iss supplied to the clock.
For the drivers I used the 74141 TTL – ICs.

Here you can see the voltage and current- diagrams of the switch mode power supply:

After the schematic was developed, the Layout cut be routed:

After the layout was done, I made some boards.
Here you can see top and bottom:

Here the equipped board:

The Clock with IN-1 Tubes:

The Clock with LC-516 Tubes:

The plate rersistors must be matched to tubes in use of course.
The tubes are mounted in sockets, so they easily can be replaced.

The Clock with IN-1 Tubes in the Case:

The Clock with LC-516 Tubes in the Case:


The code was done in C++
A crossfading- feature was implemented in the code, so the digits can be faded from one to the next.
Unfortunately this nice feature can not be catched in pictures.

Features of this Clock:

Thank you for reading and have much fun by playing around with nixies.

Yours, Dieter

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