Fixed in Version 5.5 (October, 5th 2004)

1. Fading is now active in 1pps input both in the 2 digit clock and the 6 digit clock modes.
2. Blink1 and blink2 outputs now also work in 1pps input mode. That means that blink 1 is exactly the same as it was in version 5.4. Blink 2 is active when blink 1 is not active.
3. In the 2 digit clock mode there was a bug in version 5.4 so that sometimes the 12 and 24 hour mode was impossible to change. That has been fixed now.
4. The mains frequency it has measured will now be displayed in the 2 digit mode.

This version has autodectect for 1 Hz, 50 Hz and 60 Hz. This is the default delivered version if nothing else is specified. It is the actual replacement for version 5.4.

At powerup it shows the version 3 times blinking in HR (55) then it flips the digits fast for exactly 1 sec to show counting the input frequency. Then it shows the software version in HR and input frequency in MIN for about 5 sec. Then it goes to normal clock mode. The time is now preset to 00:00:00 if in 24 hr mode, else 12:00:00 if in 12 hr mode.

12-24 hour selection Hold UP/DIM button for 3 sec to change from 12 hr to 24 hr mode and back. The EPROM will keep the setting for 12 or 24 hours mode even if the clock has been powered off..

No leading zero If you want to blank the leading zero, then just cut the connection to the first hr "zero sign".

External outputs PIN4 and PIN5 of the PIC16F876 are now outputs to drive blinking colons with, there are 0,5Hz and 1 Hz outputs (if 50Hz and 60Hz input) so you can choose the blinking speed you prefer. You need to add one more npn transistor like Q4 and a neon bulb. If you prefer an LED led just connect a 470 ohm resistor to pin 4 or pin 5. It is all up to you.

Dimming The UP/DIM button changes the 4 dim levels when clock is in normal RUN-MODE. There are 4 dimming levels. Dimm level 4 is the fading mode for 6 tubes at maximun light output.

Setting the clock Push the SET button to enter the set mode Then the UP/DIM button adds 1 to the highlighted hours or minutes. The SET/RUN mode button enters SET MODE when pressed first time, secs are reset and blanked during set mode. HOURS lights up, MINUTES are dimmed for easy indication that it is HOURS that are adjusted now. One more click on the SET/RUN button, changes to MINUTES, now HOURS are dimmed. When pressing SET/RUN the last time, the clock will start in normal run-mode.

The number of tubes mode settings

To change operating mode, hold down SET, then power up. WHILE you still hold down SET, now press DIM until right mode is working, to store this and continue, simply release SET.
To make it easy to see when right mode is chosen, the digits will display the tube number as in the schematics:

1-2 is two tube non muxed mode
1-2-3-4 is four tubes 2x2 mode using normal nixie tubes
1-2-3-4 is four tubes using dual anode tubes
1-2-3-4-5-6 is six tubes 2x3 mode

If you use the wrong mode the clock’s display will just not look right, but no harm can be done to tubes or electronics. Simply try again until it looks right.