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Old 28th June 2012, 09:35 AM   #11
mkusan is offline mkusan  Croatia
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Quote:
Originally Posted by wintermute View Post
I guess the other question that should be asked is safe for the device or safe for it's surroundings cooler means less stress on nearby components and also less likelyhood of developing dry joints.

Long legs, and a decent distance from other components should allow a higher operating temp, than mounted close to the board and close to other components.

Tony.
Hi Tony,
the board is rather empty around this regulator, except for one film cap.

I thought about extending the legs of the regulator but was not sure about its caveats, higher resistance comes to mind. And I do not have enough knowledge to determine whether extra couple of cm would have any significant impact on the regulation.

Thanks
Marko
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Old 28th June 2012, 09:39 AM   #12
MarianB is offline MarianB  Romania
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There is no need to worry about bad influence on the sorrounding components if the working temperature can be stabilised below 50 or 60 degrees, even more so if as what you say the board around it is sort of empty.
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Old 28th June 2012, 09:43 AM   #13
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The datasheet recommends connecting direct to the case of the regulator for resistance reasons. See this except from the national datasheet.

So yes lead length could make a difference depending on the implementation details

Tony.
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Old 29th June 2012, 06:25 AM   #14
mkusan is offline mkusan  Croatia
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New, bigger heat sink managed to shave-off temperature considerably.
Even the lid now seems cooler to touch.

Thanks everyone for kind advices
Marko
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Old 29th June 2012, 06:46 AM   #15
MarianB is offline MarianB  Romania
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Congrats on the succes

As i see you could even try fitting a small cooler inside, to ventilate the device and that way you will have no more worryes about the temperature, but the worm air has to be able to escape the case.
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Old 29th June 2012, 07:40 AM   #16
mkusan is offline mkusan  Croatia
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Congrats on the succes

As i see you could even try fitting a small cooler inside, to ventilate the device and that way you will have no more worryes about the temperature, but the worm air has to be able to escape the case.

Hi MarianB,
I am afraid that the small vent would be noisy, and the silent one would be expensive. I could be wrong but I have a feeling that this setup is even more cool than with the old LM7805 in place, at least judging by the lid temperature (finger testing not exact numbers here).

What I am contemplating now is a separate regulator for either SAA7220 or TDA1543. Any thoughts on that?

Thanks
Marko
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Old 29th June 2012, 07:51 AM   #17
MarianB is offline MarianB  Romania
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Well my small cooler sugestion was just that, a sugestion, as i see you could do just fine without it.

As i understand, both SAA7220 and TDA1543 requires 5V and a small current so maybe a 7805? it could even do without any heatsink if supply voltage for it is at about 9V.
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Old 29th June 2012, 08:02 AM   #18
mkusan is offline mkusan  Croatia
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Originally Posted by MarianB View Post
As i understand, both SAA7220 and TDA1543 requires 5V and a small current so maybe a 7805? it could even do without any heatsink if supply voltage for it is at about 9V.
You are absolutely correct, all these chips were powered from just one LM7805 which I now substituted with LM317. My plan was to use same inbuilt transformer which gives as already stated 9.47V and I now have one LM7805 spare. Only question is it worthwhile doing this?

Thanks
Marko
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Old 29th June 2012, 08:06 AM   #19
MarianB is offline MarianB  Romania
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Tell me please, why did you susbtitute the 7805 with 317 if it wasn't foulty?
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Old 29th June 2012, 08:18 AM   #20
mkusan is offline mkusan  Croatia
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Tell me please, why did you susbtitute the 7805 with 317 if it wasn't foulty?
No problem

Reason 1. I have to solder something, I acquired a bug on this forum which even my wife cannot cure

Reason 2. This links made me think that LM317 is superior to Lm7805
Using 3-pin regulators off-piste: part 1
Ray's Audio Page
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