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Old 9th December 2008, 09:30 AM   #121
Khron is offline Khron  Romania
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1) Change the location of the 1M with the 10ohm
2) Rotate the 330p cap by 90 degrees
3) You seemed to like my layout It's a bit more compact as well.
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Old 9th December 2008, 09:38 AM   #122
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Quote:
Originally posted by Khron
1) Change the location of the 1M with the 10ohm
2) You seemed to like my layout It's a bit more compact as well.
Ah, heatsink fits fine.
I think its nicest when the back of the chip is flush/even with the edge of the board.
Maybe you can unblock the V+ connection (like move zobel cap to right side of board)?
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Old 9th December 2008, 12:27 PM   #123
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Looks good to me. I would use a 220uf for the blocking cap and put a .1uf film cap parallel. You have the room, why not.
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Old 10th December 2008, 10:32 AM   #124
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Cool guys!

Howabout a stereo board next?

Advantages of a stereo board:
There is only 2 of 220uF caps for power.
Expected results on project completion.
Safer--The chip won't spin to slip off the insulator.
LM1875 is interesting parallel and TDA2050 is interesting bridged.
More-easily scalable for wide variety of applications.
Physically more durable.
Lower costs.
Simplified wiring.

And, given a pair of stereo boards, one can be used in parallel mode to power a 4 ohm subwoofer, while the other is used normally, as for the main speakers. This can run from just one transformer if that is your budget or preference.

Perhaps one owns 4 ohm MTM, 4to8, "difficult drive," planar, or other speaker types (use parallel)?
Perhaps one owns full range drivers at the end of very long speaker cables or regular 16 ohm speakers (use bridged)?
I think that a stereo board brings with it some economy and ease in studying the various applications of chip amps.
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Old 10th December 2008, 04:23 PM   #125
Khron is offline Khron  Romania
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Would something like this be satisfactory?
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Old 10th December 2008, 04:39 PM   #126
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by Khron
Would something like this be satisfactory?
Now that you have combined the two channels at that Central Star, how do you make a decision on where the PSU zero volt line should be referenced?
And, possibly more importantly, where do you take the speaker return wire to?
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Old 10th December 2008, 05:11 PM   #127
sneih is offline sneih  Indonesia
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finish layout of lm 1875, maybe?


Click the image to open in full size.


please comment, if everything is good i will make this revision pcb next day to replace my old pcb, thx
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Old 10th December 2008, 06:02 PM   #128
AndrewT is offline AndrewT  Scotland
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I like the alternative pin pitch pads for the two caps.
What about a similar philosophy for the six other caps?

bring the two input pads to 0.1inch pin pitch.
bring the input end of the 22k Zin to outside these two input pins, but on the hot input side.
This gives a three pin input @ 0.1inch pitch. A computer type jumper plug (0.1inch pitch) can be used to short either pin to it's neighbour.
It also allows you to bypass the input DC block if you have DC blocking at the previous stage. Finally it allows you to short the AC input to signal ground for testing and setting up.
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Old 10th December 2008, 06:54 PM   #129
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Quote:
Originally posted by Khron
Would something like this be satisfactory?
That stereo board has the right side with the power cap too close to the nfb cap and, one of the power leads crosses, via jumper, straight over the signal. The left and right won't sound identical, thus it couldn't be used parallel unless output resistors were increased quite a bit.
Other than that, its looking good.

Suggestion: Use no jumpers. The resistors can reach.
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Old 10th December 2008, 07:03 PM   #130
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Quote:
Originally posted by AndrewT
Now that you have combined the two channels at that Central Star, how do you make a decision on where the PSU zero volt line should be referenced?
And, possibly more importantly, where do you take the speaker return wire to?
Doesn't the PSU 0v connect right in the center of that stereo board?
Doesn't the speaker return connect to the 0v output terminal of the power supply board?
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