1 sec alternating polarity circuit

W

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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Solution
W
I’ve made my friend a small batch of pulsar boards now. I would like to say a big thank you to all that contributed to this, I can confirm that the boards are working perfectly.

My next challenge is to make the circuit but using less components while still
using a 3v supply. I would love to hear your feedback on this


I know the boards are a bit messy but I don’t do this every day

Again thanks
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Diver300 said:
If you have pulse shaping before the output transistors, you would need a full bridge driver with four transistors to so that the pulse could be reversed.
Click to expand...
Not if you keep the output capacitor as just an output capacitor. If its value no longer is critical to the output pulse width, its size can be determined only by the load characteristics such as the number and types of clocks. One clock, ten clocks, new replacement clocks, whatever - the pulse widths would be unaffected.

ak
 
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Update!
Hi all. This weekend I took delivery of the actual pulsar unit and an 1/2 minute slave clock.
I have the 1/2 minute slave clock now running from the pulsar unit, so I can confirm that it puts out an 30 second alternating polarity pulse.
 
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Seems like this is correct now I’ve actually tested the circuit
 
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The previous schematics should be almost 100%, a meter/continuity check against the actual board would be advised to trace the circuit out and confirm.

Also to confirm the actual transistors/output configuration is right.

Also, what is the value of the big blue capacitor and the little ceramic ones at the crystal please?
 
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Thank you for your reply. I’m out all day today so when I get back I’ll check the values.
 
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Just to be crystal (!) clear, the output waveform to the clocks is -

positive pulse > 30 second delay > negative pulse > 30 second delay > repeat

Yes / No

ak
 
Last edited:
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Hi. I hope the photos explain a little more.
The axial capacitor is 2200 u-m 16v
The ceramic cap says 8D
The grey/black cap says 39 P

And unfortunately by trying to rotate the axial cap I broke a leg but might be able to dap a bit of solder on to repair it if not I’ll have to replace it (if I can find one).

Hope this helps
 

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wombweller said:
....
The axial capacitor is 2200 u-m 16v
The ceramic cap says 8D
The grey/black cap says 39 P

......
Click to expand...
Thankyou, sorry the capacitor lead broke, normally they are little more resilient.

I would suggest putting a bit of hot melt glue of something similar under the blue cap before soldering it back for a bit of extra support - the solder joint will be a weak point now.
 
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Damn it seems like I’ll need a new cap!! The leg broke right at the base but I thought it would re attach with solder, I was wrong Try as I may the solder won’t stick to the base, I’ve tried tinning it, applying flux but no it won’t stick.
I’ll try a locate a new cap.
 
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Hi all. Can the output be fine tuned with the variable capacitor and is it not better to add one of these in the schematic, what value is the VC in the original circuit?

Many thanks
 
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