IV-6 Quarz, DCF, melody clock

© 2018

VFD clock IV-6 quarz, DCF, melody


The kit consists of two circuit boards, the control board and the display board.

This clock KIt is also avaible with Sound Module. ( possible with quarz and DCF Version KIT )

Each full hour the sound module receives a signal and play a recorded sound file. Every sound is possible lengh 10 sec. ( BibBen, gong signal and ... )


Regarding balance (accuracy), I decided for a trimmer, as you can see, what value you set about, not like ceramic trimmers.

The trimmer is not absolutely necessary because with 2 x 27pF the clock has been running very well.


I have a test watch in operation, deviation <1 second per week, that means a maximum deviation of less than one minute

a year! Tolerances due to differences in temperature +10 ° C - +45 ° C, I measured, are negligible.

A DCF77 module will follow, displaying time date each 5 sec.



Technical data:

27 volts AC 30mA

8 volts AC 60mA (including approximately 40mA for the VFD tubes )

Comparing this with the data sheet of IV-6 , you will notice that the VFD tubes do not use100 % but only about 80 %

(That means the tube results in longer lifetime)


6 digit display with decimal point between the hour and minutes

 - Brightness decimal point LEDs (cold white, corresponds to the color of the VFD 's) adjustable via potentiometer .

 (Board prepared for decimal addition between minute and second)


VFD tubes IV 6 hour and minute , IV -3A for seconds.

(to display seconds you can also use IV-6 ; R5 + R6 are omitted)


Control the clock on AT89C2051 microcontroller clocked at 12Mhz (Battery- case of power failure)

- The resonant circuit (quartz) can be controlled via trimmer. (Accuracy)

The board is prepared for DCF77 input and 3.9 volt power supply DCF module.


Control of the VFD tubes 2 x Driver IC LB1240, resulting in low component count.

Blue glowing LEDs 3 mm below the VFD tubes, switchable via slide switch.


Soldering points for two housing LED's on the display board, and switchable connections for LED's on the control module.

(Slide switch position 1 = blue LEDs below the tubes, position 2 = additional casing LED 's)


Power supply AC 230V 65mA - 160mA AC 27Volt - 100mA AC 8Volt

Control and display board from industrial production with solder mask, HAL lead free.

Kit including all components + test leads (alligator clips) and universal mini screwdriver for adjustment.


Price for IV-6 KIT quarz without case € 62,00 + shipping.



The clock with OpenSky2 housing.


The circuit, finale version.


IV-6 melody clock.

It is possible, IV-6 quarz version, to use a sound module. Each full hour a sound signal, MP3 size.

Ask for.