1 sec alternating polarity circuit

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wombweller

Member
Hello all.
Please see the attached photo of a circuit I’d like to copy. I don’t have the actual board a friend of mine sent me the photo.

It’s a circuit to produce 1 second alternating pulse using the following IC’s-
CD4017B x2, CD4060B x1 and a CD4024B.

Can anyone point me to a circuit diagram for this, maybe there is something online, if there is I’m unable to find it.

I think this circuit is used so it can run on 3v so low power. It’s for pulsing a low voltage Brillie slave clock and needs to be a small footprint so it can go in to the back of the clock and run on batteries.

I look forward to hearing from you.

Regards
Mark
 

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Can you get a photograph of the back? It should be possible to work out the circuit from that.

Some things can be guessed. There's a crystal oscillator circuit with trimmer capacitor in the top left. That is connected to the inverter input and output on the CD4060. The crystal is a 32768 Hz watch crystal, so the lowest output frequency of the CD4060 will be 2 Hz.

After that, more information is needed. The CD4024 is a 7 stage counter, so it probably divides the 2 Hz frequency further but it might be connected to something else. The wire in the middle of the board may connect the clock input on the CD4024 to an output from on of the CD4017s.

The CD4017s are decade counters which turn on one of their 10 outputs, so those could be used for producing short pulses.

There are two transistors, probably to drive the output, but I don't know why there are two. The capacitor is large than I would expect.
 
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It would be a LOT simpler to use a PIC to do the job, and require hardly any components at all - a nice small 8 pin PIC, a 32KHz watch type crystal, a couple of capacitors, perhaps a resistor or two. It would require a little programming, but the MCC would do almost all of it for you, and it would be far smaller than the decades old complicated version.
 
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Ha you’re right Nigel.
I was actually going to replicate this using an Arduino nano an RTC and a small relay but it needs to a 3-6v or max a 9v battery pack to keep it all self contained in to the clock. I’m not sure how long the batteries would last going this route.

Thanks for your reply.
 
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augustinetez said:
If it makes it any easier to trace, here are the two photo's side by side with the bottom mirrored.

Bryan Mumford was the doyen of clock drivers, but I couldn't find this one on his website.

View attachment 148270
Click to expand...
Thanks for that. Mumford stopped doing drivers yonks ago.

I like the one in the link but I’m unsure on how it would fare on a battery pack.

Driving Slave Clocks With Arduino

ESP - Driving Slave Clocks With Arduino
sound-au.com
Click to expand...
 
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A small PIC working with a 32KHz crystal on TMR1 can spend all of it's time in sleep an uses almost no current at all. You program TMR1 to generate an interrupt - the program wakes up, does what it needs to do, and goes back to sleep again. The battery life should be limited by the shelf life of the battery.

The most 'current heavy' part of the circuit is probably what the output has to do?.
 
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To get a high accuracy clock use a cheap GPS module ? Use 1 PPS output of it.


Or use a low end ATTINY85 to generate this (with xtal attached to it) :



User drags and drops blocks out of second window, into third window, configures, like pin to use for clk, and mBlock gens code shown in right hand window. Third window generates the 1 Hz signal, simple,
thats all it took to create program.

An example of a complex timer / pulse generator design, eg. the utility and ease of programing in
block language. https://www.electro-tech-online.com/articles/pulse-sequence-generator-smart-timer.938/

mBlock takes user configured block programing and generates Arduino code user programs into ATTINY85 or Nano board, using Arduino IDE programmer facility. mBlock is free, as is Arduino IDE.

Simplest use a Nano board as its has regulator and xtal on it, easily interfaces to Arduino IDE programmer
from mBlock. Pic of ATTINY85, and shown in foreground Nano board. Use one or the other.



If you wanted to get fancy use ESP8266 or ESP32 and add a web page access to GPS time.
Use Tuniot to do the block programing.


Regards, Dana.
 
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Hi Dana. That’s some really useful information, I’m going to digest it and see where it leads to.
Many thanks
 
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Hi. I think the Microcontroller of some description is definitely the way to go, an ATiny85 or an Atmega328, I’m thinking barebones Arduino pro mini. It has to be low power consumption and low operating voltage.
The PCF8563 real-time clock looks to be the obvious choice for the RTC. unless otherwise advised.
The L9110H H-Bridge driver looks to also compatible with the requirements, again unless otherwise advised.

All in all the footprint will be small and the components minimal

Many thanks
 
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Just to confirm that it is supplying a once per second inverted pulse - some Brillie slave clock's used a pulse once every 30 seconds according to what I've seen on the various Horology forums.

If I get enough time, I'll see if I can draw this one up.
 
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This is a very quick mud map of the connections (no guarantee it is 100% correct).

The area in the red box is my guess only until we can find out what the transistors are ie we need the part numbers if possible. The values on the three capacitors would help too (I 'think' the trimmer is a 5-60pF one).

 
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I have a sneaking suspicion this unit gives 1 pulse per 30 seconds - hopefully somebody more adept at working with these chips can confirm (or otherwise) my calculations:

The output of the 4060 (pin 15 , Q10) is 32768Hz ÷ 1024 = 32Hz

4024 output Q6 is ÷ 32 = 1Hz

First 4017 is count of 5 and the second 4017 is count of 6 = 5 x 6 = 30seconds.
 
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Wow!! That’s a lot of work you put in there, thank you
As I said previously I don’t have this circuit a photo was sent to me by a friend so its difficult for me to be 100% sure on what is going on with it.
BUT ! from your post I decided to take a look on line how many ppm the slave clocks need and I’m of the opinion that it is 1 pulse every 30 seconds. On that I do now believe that your findings are correct . I did ask my friend who hasn’t got back to me yet but I think I was led up the wrong garden path.
Unfortunately for me I’m working today so once I’m home I’ll take a close look at your circuit.
Once again thank you.
 
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I believe the two transistors are 2222A. I have another photo from the side.
 
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