TTL-ClocK Elektor 1974

This TTL-clock is build in 1974 by me, off a Elektor design which get the time puls from the main power-frequency.

Unfortunately is the time-accuracy too bad and the clock is after a long time off use, I putting it away in a cabinet.

Now after 39 year I  give it a new lifetime, I made the clock-frequency with a Micro-Prosessor programmed in PicBasic. Because these clock can only count forward to set the time, and by wintertime the clock must 1 hour back, that is the same as 23 hour forward and that is nice programming. On the backside I have 2 push-switches, 1 for 23 hour forward and 1 for 1 hour forward. Both 23 hour and 1 hour forward wait time is +/- 5 sec. wait time . The prosessor have a 4 Mhz crystal.
The old time-setting  is not changed, with 50 Hz and 1 Hz. (right hand with push-switch and turn-switch)



The clock on desk in the hobby shop.


The clock open on the backside, witch in the middle the "Elektor" print.


The PIC print is in the upper-right in the corner located.
Micro processor is a 12F629 witch a 4 MHz crystal.


The push switches for the Winter and Summer-time setting


Up. The test and design at the "breadboard"

Low. Schema, sec. display not made in the clock.


 Clock description: Unfortunately only in Dutch (up)




Download  Hex code, upper Picture, Asm and PicBasic source program  <== click


 I have used single led's as Display and at the follow manner, 3 led's serial, with 2 transistor for a better display from the  6 and the 9 (a and d segment). But the same result you can get by using the driver 74LS247 instead off the 7447 and that one uses less power !

Use only RED led's from 5mm , only that workt with-out manny resistors (1 resistor pro led = 28 pro sigment)

But that is not working with the newer Chinese red led's any more, you need a little more voltage, and that is possible because the driver has a open-collector output with a max. off 15 volt. There is only 5.8 - 6.5 max. necessesary for a bright led. Therefore you need 2 power supply, 1  (one) 5 volt for the logic and 1 (one) 5.8 for the led's.

100 red leds from the cost only $2.00 - $2.50   <== klik







The new 2014 power supply:

I use a cheap power-adapter 230 volt -> 12Volt  DC  1Amp. (E-bay $3.00), but you can also use a tranformer from 8-9 volt AC  1 A.

Power source is not critical (max 25 volt input) , but more voltage need bigger cooling-plate and you can waste power.

Then I make 5 Volt with a LM7805 voltage regelator and a
LM317 to make 5.8 volt off the 9 volt. R1= 330 and R4,R7= 1110 Ohm

With R2 and R3 you can make 5.3, 5.8 and 6.3 Volt for the intensity of de leds, on de backside are the switches connect to J1.



 2014 The new version of the TTL-clock:

After 40 years I make the same clock with low current components, also without a seconds display but with a micro-processor  for the clock pulse and setting, the TTL in LS (low power / schotty) design and the led current segment at 4 mA. The old 7413 smith-trigger is not easy to buy, so the time-setting is a job for the micro-processor. (see drawing)

TTL klok logik 4 pic.jpg


 The transistors T1 and T2 replaced a 1/2 7413 chip because there is not one nand gate over and I donīt want to use a hole chip only for 1 gate, witch only is used to set the clock with S2 en S3. The counters 74LS90  and drivers 74LS247 are cheap on the E-Bay , 10 pcs at $5.70 with shipping from China.

I donīt have a pcb for the new clock, I use a vero-bord and then wiring with a wiringpen.
conrad Bestelnr.: 532630 - 89



10 pcs board (5x7cm) at $1.80 op de e-bay

10pcs 7x9 cm DIY Prototype Paper PCB Panel Universal Board $3.10

      Klick for a description of the pen to make one by your self.


A thin plate material (aluminium, pcb or plastic) that you can paint it black for the clock-leds.

My new clock is 11 x 23 cm and 8 cm high led segments.



CNC Bohrcode to drill all the hole 88 88


Backside    - middle the power and clock PIC with 2 cooling plates  -  right, counters minuts drivers  -  left, hour counters and drivers



Jou see that I the segment at pieces vero-bord has made, easy to replace and no big vero-bord needed, the leds are with 3 in serie powered.


Backside cabinet  aluminium 1 cm inside, right side  info card glide in



 Cabinet from black perspex with a clear red perspex  fore side.

perspex : Polymethylmethacrylaat (PMMA)

It is runnung now and is stable  . . February  4 - 2014


 Download  Hex code, with a 12F683, Asm and PicBasic  program  <== klik hex code with 50Hz set-clock


schema 1sec50.jpg

 Wintertijd  = Wintertime    and   Zomertijd =  Summertime   at time zone Amsterdam / Paris



 The diverence between a 12F629 and a 12F683  is only the memory, 1k or 2k ,you can use both bycause the hex code is not bigger then 1K , but the 12F683 is better and cheaper to buy (80-90 $ cent pcs).





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