My First Thread, I apologise for any mistakes.
I have a classic car clock that is running at double speed i.e. 30 sec to do 1 min, it has a very simple circuit and seems to be a larger version of the normal quartz wall clock, it has a coil that needs a momentary 12v pulse every 1 second which reverses 180 degrees every alternate pulse, my issue is that I cannot identify the crystal frequency and the chip is no longer available (please see attached pictures) my original idea was to replace the components, which I did the resistors and capacitors although they were testing fine. I could replace the clock but I want to keep the dials original, I also like a project. Would anyone on the forum have any ideas for a circuit I could use to replace the chip or an equivalent chip as I cannot find it in my old reference books. I have looked at 555 timers but they do not seem accurate enough, I have also found a thread on using a 1.5v wall clock inards but due to the reversal pulse I am having difficulty increasing the output to 12v.
many thanks
Jim

 

This might help (but not much):

https://translate.google.co.uk/translate?hl=en&sl=ru&u=http://radiokot.ru/forum/viewtopic.php?f=29&t=44566&view=previous&prev=search

http://radiokot.ru/forum/download/file.php?id=60322&sid=23ed5f62273bdc1e1940a47e59976756

I would try replacing the crystal.

 

Go to a junk yard. Get a brand new used one.

 

This might help:

https://translate.google.co.uk/translate?hl=en&sl=ru&u=http://radiokot.ru/forum/viewtopic.php?f=29&t=44566&view=previous&prev=search

http://radiokot.ru/forum/download/file.php?id=60322&sid=23ed5f62273bdc1e1940a47e59976756

I would try replacing the crystal.

Thanks, I will order a crystal today

 

The Xtal used now in clocks is 32.768Khz, which is a power of 2 (8000hex) represented by 15 bits and rolls over every 1 sec.
It is very simple to make a clock from a small pic that has xtal input for Timer1.
Max.

 

I had a battery powered wall clock that also suddenly started doing the same thing.
I suspect that it started operating at the crystal second harmonic overtone due to either a change in the crystal or one of the small associated crystal load capacitor(s).
You might try adding a small capacitor (10pf-20pf) from either or both of the crystal terminals to ground to see if that has any effect.

 

I have ordered a new crystal, thanks I am going to try the capacitors as well.

 

Is this a mechanical clock? The shape of the PCB and the small IC pin count makes me think so. It might be a mechanical or electrical problem in the motor if it is.

Also, the crystal seems awful large for a typical 32,768 Hz crystal. Maybe they were larger when the clock was manufactured or the auto environment dictated that larger size?

 

Mercedes were using this IC in their clocks in the early 60's so I am guessing that there was not the demand for miniature watch crystals at that time.
If it is not digital, it is (semi-clockwork) mechanical.
Max.

 

Duh. Read all of the original post.

Obviously a clock motor driven like digital watch motors. I think that it is probably a 8.192 MHz crystal divided down and split into the two phase pulses for the motor.

 

Duh. Read all of the original post.

.

?????????

 

?????????

I meant that I had re-read the post and realized that the poster had already said that the clock had a moter.

 

Hi All,
crystal replaced, still double the speed (counted the pulses 60 in 30 seconds, so not a mechanical problem), waiting for the 10pf capacitors to arrive to see if that helps, Max you mentioned a PIC to could do the job, I tried PIC programming a few years ago an to be honest it was beyond me kept getting very strange result with the programming, do you have a circuit and the code for a project like this,
thanks all for your help

 

This is the original code I found and used in a project, but I converted it for the 18F series.
It just flashes a LED every 1 second, so it should be relatively easy to adapt it.
It uses a 32Khz crystal on T1OSCI and T1OSCO
Max.

;=======SECONDS.ASM=================================9/30/02==
        list    p=16f870
    __config  h'3f71'
        radix   hex
;------------------------------------------------------------
;seconds demo
;    external oscillator, 32768 Hz, timer 1, prescaler 1:1
;------------------------------------------------------------
;       cpu equates (memory map)

;------------------------------------------------------------
;------------------------------------------------------------
        org     0x000
    goto    start    ;skip over location pointed to by
            ;   interrupt vector
    org    0x004
    goto    iserv
;
start:
        bsf        STATUS,    RP0  ;switch to bank 1
        movlw   b'00000000' ;port B outputs
        movwf    TRISB
        movlw    b'00000110' ;turn off A/D, port A
        movwf    ADCON1
        bcf        STATUS,    RP0  ;switch back to bank 0
        movlw    b'00000000' ;port B lines low
        movwf    PORTB
        bcf        INTCON,    7    ;disable global interrupts
        bcf        INTCON,    6    ;disable peripheral interrupts
        bsf        STATUS,    RP0  ;bank 1
        bcf        PIE1,    0    ;disable tmr1 interrupts
        bcf        STATUS,    RP0  ;bank 0
        bcf        PIR1,    0        ;clear timer 1 interrupt flag
        movlw    b'00001010' ;prescaler and tmr1 setup,
        movwf    T1CON        ;   tmr1 off
        clrf    TMR1H    ;clear timer 1 high
        clrf    tmr1l    ;clear timer 1 low, clear prescaler
        bsf        INTCON,    7    ;enable global interrupts
        bsf        INTCON,    6    ;enable peripheral interrupts
        bsf        STATUS,    RP0  ;bank 1
        bsf        PIE1,    0    ;enable tmr1 interrupts
        bcf        STATUS,    RP0  ;bank 0
        bsf        T1CON,    0    ;timer 1 on
circle:
        goto    circle
;------------------------------------------------------------
iserv:
        bcf        PIR1,    0    ;clear timer 1 interrupt flag
        bsf        TMR1H,    7    ;set up timer 1 to roll over at
            ;   32,768 counts
        btfss    PORTB,    0    ;port B, bit 0 STATUS?
        goto    setbit    ;bit is clear
clrbit:
        bcf        PORTB,    0    ;clear port B, bit 0
        retfie        ;return from interrupt
setbit:
        bsf        PORTB,    0    ;set port B, bit 0
        retfie        ;return from interrupt
;------------------------------------------------------------
        end
;------------------------------------------------------------
;at device programming time, select:
;       memory unprotected
;       watchdog timer disabled (default is enabled)
;       standard crystal XT (using 4 MHz osc for test)
;       power-up timer on
;    brown-out reset enabled
;    lvp disabled
;    debug mode disabled
;============================================================

 

I don't know whether they would sell you just one, or how much it would cost:
http://www.marscomponents.com/parts...5419ae,scl5419e,SCL610,SCL770_705557_507.html

 

The SAJ300R looks like it might be equivalent. See the attached pdf.

 

Thanks, that chip is the one, I am going to try the capacitors on the crystal then if that does not work then a new chip it is, thanks for everyones help.

 

Thank you all for your help, It was the chip, now working perfectly.