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Old 6th January 2014, 02:06 PM   #41
Trileru is online now Trileru  Romania
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I just wanted to set it at about 40-50mA for good measure. Can always be left out if case...
I appreciate your ideas thou, not much feedback on this and being my first ever PCB I like feedback
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Old 6th January 2014, 10:59 PM   #42
Trileru is online now Trileru  Romania
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Someone told me how to remove the layers from the heatsink and now I can do a full ground plane. I also made a 3d rendering of the board so I have an idea on how it will look like. Pretty neat!
I will probably get some tantalum capacitors on the ADJ and output but for the test it's nice.
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File Type: png LM338 regulator.png (527.3 KB, 61 views)
File Type: png LM338 regulator 2.png (503.5 KB, 56 views)
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Old 8th January 2014, 04:49 AM   #43
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It is advisable to drill holes on the pcb, near the periphery of the heatsink.

Gajanan Phadte
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Old 8th January 2014, 08:06 AM   #44
Trileru is online now Trileru  Romania
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Quote:
Originally Posted by gmphadte View Post
It is advisable to drill holes on the pcb, near the periphery of the heatsink.

Gajanan Phadte
I don't understand. You mean the securing holes? I guess that at the board's size that wouldn't matter as it's pretty stiff and the weight on it is not that much but I guess I could try to fit an extra one near the heatsink somewhere.
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Old 8th January 2014, 09:25 AM   #45
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No, these will allow air passage over the heat sink from beneath the pcb.

Gajanan Phadte
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Old 8th January 2014, 10:21 AM   #46
Trileru is online now Trileru  Romania
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Oh, that's good! Haven't thought of that!
I will do it. Any ideas on how many and what size...in general?
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Old 8th January 2014, 08:15 PM   #47
00940 is offline 00940  Belgium
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A few comments:

- Think in terms of power planes. There's no reason your positive power traces should be so much smaller than the ground traces.

- There's an optimal way to connect r1 and r2 for optimal performance: r1 should be connected as close as possible to the output pin of the reg, not sharing the output track (or as little as possible) and the ground side of r2/c5 should not be tied to the power groundplane but by a dedicated track directly to the gnd ouput terminal.
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Old 9th January 2014, 03:59 AM   #48
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4-6 holes on each side of about 3-4 mm diameter should be fine.

Gajanan Phadte
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Old 10th January 2014, 09:25 AM   #49
yd1cvj is offline yd1cvj  Indonesia
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Hi Trileru,
I found from web also regulated with LT1083.
What is your main reason use LM338 ?
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Old 10th January 2014, 09:30 AM   #50
Trileru is online now Trileru  Romania
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Quote:
Originally Posted by 00940 View Post
A few comments:

- Think in terms of power planes. There's no reason your positive power traces should be so much smaller than the ground traces.

- There's an optimal way to connect r1 and r2 for optimal performance: r1 should be connected as close as possible to the output pin of the reg, not sharing the output track (or as little as possible) and the ground side of r2/c5 should not be tied to the power groundplane but by a dedicated track directly to the gnd ouput terminal.

You mean like this?
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Last edited by Trileru; 10th January 2014 at 09:33 AM.
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