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The Kuartlotron - keantoken's simple error-correction superbuffer
The Kuartlotron - keantoken's simple error-correction superbuffer
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Old 19th August 2015, 08:16 PM   #381
jean-paul is offline jean-paul  Netherlands
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Crosstalk....
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Old 19th August 2015, 08:47 PM   #382
Destroyer OS is offline Destroyer OS  United States
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The Kuartlotron - keantoken's simple error-correction superbuffer
Quote:
Originally Posted by jean-paul View Post
Crosstalk....
Because parts aren't turned on the parasitic capacitance is like having several mini antennas? Meh, might not be anything amoutnable. Perhaps there's a coupling scheme for RD bypass, and/or an orientation for cancellation.
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Old 20th August 2015, 12:03 AM   #383
nattawa is offline nattawa  Canada
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Quote:
Originally Posted by keantoken View Post
Good work!

Does anyone see a problem with using the relays like this, to save space on the board?
Looks good to me in general.

Some minor details perhaps could be put into consideration when carrying out the real layout design:

1) miniature relays such as Fujitsu Takamisawa A-series have "helper" permanent magnet in them, and require power to be applied to coil in correct polarity, pin 1 of the relay must be at positive potential (picture attached). Otherwise the relay wont fire despite sufficient current in the coil. Your layout is correct if it is top view shown.

2) If layout is to be made Fujitsu miniature relay compatible, the common positive supply to the coils may have to run on the bottom side of the PCB, As the small relay does not have a skipped pin space between the coil pins and the signal pins.

3) I don't know how much a guarding ground trace around the signal traces and pins can help keeping crosstalk down. Using small relays makes it very hard to deploy guarding ground traces if possible at all, as it would require three traces to go between the pins 2.54mm apart, quite do-able if SMD mount the relays though. However if SMD mount the replays, they must be spaced apart much more to allow a soldering tip to go in between. Seems to be a dilemma here.

4) Is a 4-conductor input signal connector for each relay more suitable, so that L and R signals can have their individual return/shield back to the RCA jacks? I usually use RG174 to wire off the RCAs, so a 4-pin connector will help in my case.

Just some thought. I may have gone too far over.
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Old 20th August 2015, 04:03 AM   #384
keantoken is offline keantoken  United States
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Good points.

1: I defaulted to Panasonic AGN. Those Fujitsu relays have still yet another layout than the Panasonic AGN. Maybe it is possible to support them with some trickyness.

2: Maybe not, it depends on whether there is any danger running 12mA through a 10mil or so trace. I doubt it.

3: Notice the ground plane. The improvement over that from a top layer guard trace would probably be insignificant. And the capacitance is probably what, 5pF? Consider that the source cable probably already has 200pF at least shunting the signal, so this is really a very small problem if at all.

4: Ground switching opens a path large for RF ground noises through crosstalk because the grounds are free to radiate noise into other signal lines statically. This is something that could make the relay spacing matter, as well as take up too much space on the board.

Thank you for your suggestions.
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Last edited by keantoken; 20th August 2015 at 04:06 AM.
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Old 20th August 2015, 05:39 AM   #385
nattawa is offline nattawa  Canada
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AGNs have 2.2mm pin spacing, even smaller than Fujitsu miniature type, perhaps similar to its ultra miniature lines. Anyways I'll take whatever relays you decide to use

A 10-mil trace can pass a lot of current without cooking, This calculator indicates 10-mil 1-oz surface layer trace can do 440mA at 2C rise over 25C ambien with drop of 21mV/in.

The common L and R traces run in parallel to each other over the span of 6 relays (2" perhaps?) and that's where my thought of guarding ground arose. I don't expect it to be a real issue though.

Never meant to have ground switched, just one more hole on ground per each stereo channel so that the braid lead of left and right cables coming off the pair of RCA jacks don't have to share a same ground hole.
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Old 20th August 2015, 05:51 AM   #386
jean-paul is offline jean-paul  Netherlands
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Quote:
Originally Posted by nattawa View Post
Never meant to have ground switched, just one more hole on ground per each stereo channel so that the braid lead of left and right cables coming off the pair of RCA jacks don't have to share a same ground hole.
Yes, that's better.
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Old 20th August 2015, 06:03 AM   #387
keantoken is offline keantoken  United States
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How much better really? I don't see a point, all grounds must be tied at some point so it will have little effect on the actual noise level.

Users would have to crimp on new connectors, the aim was to have a drop-in replacement. If I'm going to make "improvements" to the original layout, the reason should be compelling.
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Old 20th August 2015, 08:29 AM   #388
thimios is offline thimios  Greece
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The Kuartlotron - keantoken's simple error-correction superbuffer
Quote:
Originally Posted by Project16 View Post
Hello everyone!

My two cards are completed and just have to make the settings and proceed to testing. They will be positioned one over the other.

Regard's!
Nice DIY pcb!
Waiting for your test
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Old 22nd August 2015, 03:52 PM   #389
Project16 is offline Project16  France
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I have made the settings with a voltage +/-10V (my Borbely - Sulzer) and exactly 5V on TP. The offset voltage output ranges from 0.00 to 0.03 (200mV position on my multimeter) on both cards.
I do not have an oscilloscope and tomorrow I make listening test with my CD player and my amplifier but I have a question.
I can not find the post or we talk about volume control, what value for my test I can use?

Thank you!
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Old 22nd August 2015, 04:07 PM   #390
keantoken is offline keantoken  United States
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If you put it after the buffer, use a 10k pot or even 5k. If you put it before, a high resistance pot would be better, such as 50k. 200k could even be used, but I don't know whether it would be better or worse.
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