docuenglishv56.pdf

Documentation of DCF77 Nixieclock kit

November 2004 (rev. 10022)

The DCF77 radio controlled clocks receives the official time of the Federal Republic of Germany from Physikalisch-Technischen

Bundesanstalt (PTB) in Braunschweig and transmit it to computers and systems via various interfaces. The radio synchronisation of

the DCF77 transmitter in Mainflingen (50 01 N, 9 00 0) reaches a long term accuracy of the PTB-calibration standard of 1 x 10 E-13

per week or less than 1 second in 300,000 years.

This station transmits continuously, except for short interruptions due to technical faults or maintenance. Longer breaks may be

experienced during thunderstorms attaching the location of the transmitter.

Time Signals Except of the second marker 59, the carrier is modulated by second markers each minute signifying that the next

marker will be the minute one. At the beginning of each second the signal amplitude is reduced to 25% for 100 ms or 200ms. The

start of the decrease of the signal amplitude marks the exact beginning of the second. The second markers are phase- synchronous

with the DCF77-signal. In general: the inaccuracy of the received DCF77 times signal is large compared to the emitted time signal.

The reception depends largely on the limited wave band of the time signal transmitter and other natural interferences.

At a distance of some 100 kilometres, a time signal uncertainty of less than 0.1 ms is achievable. (Text by Hopf Electronic)

1. Attention - Important

Please read the documentation before you start to solder.

Readers should only attempt to build this design if they are competent at electronics assembly and understand the

dangers of mains voltages. No responsibility is accepted for any damage, injury (however serious) or death caused by

anything remotely connected to this website. Function of the DCF77 clock can not be guaranteed, if the signal is not

strong enough.

2. Part list

Used Part

Type

Footprint

4 MHz

Xtal or resonator

B380 C1500

D1-D4/D5-D8

5V6

D11

1 4.7uF to 22uF 350-360V

10k

R16 R17 R18 R19

10u-100u 16-25V

C3 C10

33k

R15 R20 R21 R22

100k

R1 R3 R5

100n

C5 C7 C8 C9

1-100n / 250V

C13

330u-470uF 16-25V

C11

470k

R2 R4 R6 R7

7805

IC2

74141

IC3 IC4

MPSA42

Q4 Q5 Q6

MPSA92

Q1 Q2 Q3

PIC16F876

IC1

sockets for ICs

Extra for DCF77 reception (not on the PCB – but included in the kit)

3 470 ohm R30, R31, R32 (for LEDs)

1 10 K R 33 – (pull up for DCF77 module)

2 capacitor 22p C30, C31

1 Duo LED (red green) D30 (signal quality meter)

1 LED - any colour D31 – (as indicator for an approved DCF77 minute signal or as a warning LED)

The component side of the clock PCB.

3. The power supply

The following parts are not soldered to the pcb : R14, D9, D10, C12. The pictures show all parts soldered from a

different version. You do not need the parts R14, D9, D10 and C12!!

The unloaded voltage of the power supply is about 230 volts DC. Be careful not to connect the high voltage line to the

5 volt line. When the tubes are connected the voltage will drop to about 170 – 180 volts.

If you use 115 volts please look at the picture above. Cut the track from pin 2 to pin 4 and solder new wires as shown

in red.

4. Making the PSU

Very important:

You have to ground the clock otherwise a clean signal will not be receivable.

This pictures show the psu for 230 volt ac

Here are all parts used for the psu.

Now solder the rectifiers. Watch out the long leg is plus. You can in the picture how the rectifiers have to be mounted.

Solder the capacitors now. Watch out for correct plus and minus.

Now solder the 7805. Watch out for the cooling part. You can see a white rectangle on the PCB that is where the

cooling part must be.

Solder the transformer. Solder a connector in J1 to make a connection from the psu to the clock PCB via a 4 wire

cable later. Watch out for high voltage when connecting the psu to mains!!

Now solder the mains as shown in the schematic in chapter 2. If you use 115 volts follow the description in chapter 3.

– Danger high voltage .

Check all soldering and get a multimeter set to DC. Measure as shown in the photo

You should measure 240-250 Volt DC between pin1 and GND on J6.without any tubes mounted. Don’t touch any

parts on the board.

Now make the second measurement as shown in the photo. Voltage should be 5V DC between pin 3 and GND on J6.

The psu is now ready. Unplug the psu and go on with making the clock PCB.

5. Making the connections

If you have finished the psu and the clock PCB check all soldering and double check them again. Now you have to

connect the psu and the clock kit with a 4 wire cable. Please be careful and make a marking so you do not mix up the

high voltage line with the 5 volt line!

Here is how to connect the pcbs, the switches and the tubes:

These connectors are very good to solder and give a firm contact.

Even the wires are connected for the tubes.

6. Overview of software modes - all using the same hardware

Mode 1 for 6 tubes

Display update speed is 600Hz for all 6 digits, so this is really a non-flicker display. The special feature of this kit is

the fading of the digits in the max brightness’ setting. The connections from the controller part to the Nixie tubes are

made with wires, so that nearly all nixies types can be used.

Mode 2 for 4 tubes

Display update speed is 600Hz for all 6 digits, so this is really a non-flicker display.

The connections from the controller part to the Nixie tubes are made with wires, so that nearly all Nixie types can be

used.

Mode 3 for 4 tubes (Dual Anodes e.g. 1030)

Display update speed is 600Hz for all 6 digits, so this is really a non-flicker display. The connections from the

controller part to the Nixie tubes are made with wires, so that nearly all Nixie types can be used.

Mode 4 for 2 tubes

The time is displayed with 2 tubes. The hours are shown, then the minutes and so on. That is done by fading the

digits. It looks absolutely great, when the digits are fading. This version is directly driven, not multiplexed.

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