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PostPosted: Sat Jan 29, 2022 5:47 pm 
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Joined: Sun Sep 08, 2013 10:24 am
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Location: A missile silo somewhere under southern England
Hi guys

Recently BDD has pointed me towards his clock stretching delay circuit.
The full description and discussion can be found here (it's worth a read if you're interested and shows the basic circuit design):
To test my Kicad design skills (learned over Christmas) I designed some 2 layer and 4 layer PCBs and had them fab’d. The 2 layer ones are based on BDD’s design.
Here’s a not-so-exciting video showing the circuit in action:
https://www.youtube.com/watch?v=7NDm1zESl4s

BDD has graciously given permission for me to post the gerbers based off of his circuit design for others to use, so if anyone is interested here they are:
Attachment:
Gerbers.zip [83.74 KiB]
Downloaded 27 times


Note that you should fit R5 and link/bridge R4 or fit R4 and link/bridge R5 or if you are linking from an existing PCB/project, leave both unfitted.
The circuit takes from 12 to 13mA all in (which includes a 20MHz crystal oscillator which I think most of the power goes towards).


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PostPosted: Sat Jan 29, 2022 8:11 pm 
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I watched the video and noticed you have a gadget called a SyncClocker in your test setup. Did you make that item as well?

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PostPosted: Sat Jan 29, 2022 8:28 pm 
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Joined: Sun Sep 08, 2013 10:24 am
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Location: A missile silo somewhere under southern England
I did indeed. I find it useful, although it's a bit overblown for simply generating clocks :lol:. It's got an ATMEGA 328P in it which bit bangs a clock (via a timer interrupt) out directly & also an inverted version.
It also has another 2 sets of outputs (using the same clock out signal): 1 set is from the Q and /Q from a D-type flipflop and the other which has also gone through the other D-type flipflop on the same IC as well. Hence the 100%, 50% and 25% 'speed' options.
Frequency-wise it does 0.5Hz, doubling on each increment up to 128KHz, which can be paused. It also has a single stepper feature as well.

It's handy, although I might just get a signal generator at some point if I can afford it, but that might be a bit wasted on me for what I deal with.


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PostPosted: Sat Jan 29, 2022 8:40 pm 
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Joined: Sun Sep 08, 2013 10:24 am
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Location: A missile silo somewhere under southern England
I forgot to add the photos. Here you go (hotsnot included :D ):

Attachment:
DelayCircuit_Populated.gif
DelayCircuit_Populated.gif [ 258.14 KiB | Viewed 321 times ]

Attachment:
DelayCircuit_Underside_Populated.gif
DelayCircuit_Underside_Populated.gif [ 256.12 KiB | Viewed 321 times ]

Attachment:
DelayCircuit_Unpopulated.gif
DelayCircuit_Unpopulated.gif [ 246.07 KiB | Viewed 321 times ]

Attachment:
DelayCircuit_Underside_Unpopulated.gif
DelayCircuit_Underside_Unpopulated.gif [ 247.33 KiB | Viewed 321 times ]


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