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Doug Self Preamp from Linear Audio #5
Doug Self Preamp from Linear Audio #5
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Old 9th June 2018, 04:07 PM   #1051
jwilhelm is offline jwilhelm  Canada
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Join Date: Jun 2014
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Quote:
Originally Posted by Carl_Huff View Post
Hello Jeff,

It's good to see you here. The 1.25 inch heat sinks work fine. In fact the heat sinks in the project BOM are 1 inch tall.
Thanks Carl, I didn't actually see a part number for the heat sinks in the BOM.
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Old 9th June 2018, 04:11 PM   #1052
jwilhelm is offline jwilhelm  Canada
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Quote:
Originally Posted by asuslover View Post
I think voltage drop X(times) current used is more important, not the transformer secondary voltage.
Voltage drop is dictated by the secondary voltage of the transformer, that's why I mentioned it. The target output voltage is +/- 18VDC. Likely this could be achieved from 15VAC secondaries in the transformer. If heat was going to be an issue I would switch to the later transformer.
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Old 9th June 2018, 06:28 PM   #1053
rsavas is offline rsavas  Canada
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Since LM317/337 is real cheap, you can use 2 of them, one as a pre-regulator, you can achieve >100dB PSRR. Makes for a smaller/cheaper ecap, so cost maybe lower overall and better performance = win/win
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Old 10th June 2018, 07:17 PM   #1054
fvzeppelin is offline fvzeppelin  Germany
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Quote:
Originally Posted by jwilhelm View Post
Voltage drop is dictated by the secondary voltage of the transformer, that's why I mentioned it. The target output voltage is +/- 18VDC. Likely this could be achieved from 15VAC secondaries in the transformer. If heat was going to be an issue I would switch to the later transformer.
I wouldn't go too close to the lower limit with the transformer as the input voltage typically is not very stable. As you go for 18V DC outputs, I assume you only want the best The rather low power consumption of the preamp will help you - there has been a discussion about it within this thread.
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Old 22nd June 2018, 12:15 AM   #1055
Unkgd is offline Unkgd  United States
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Default What type of fuse on power supply?

Getting ready to order up all of the parts for this project. I have most of the boards from Carl and the remainder is on it's way to me.

Question - what type of fuse is everyone using on the power supply; slo-blow, normal or fast blow?

TIA,
Bill
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Old 22nd June 2018, 04:01 PM   #1056
fvzeppelin is offline fvzeppelin  Germany
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Quote:
Originally Posted by Unkgd View Post
Getting ready to order up all of the parts for this project. I have most of the boards from Carl and the remainder is on it's way to me.

Question - what type of fuse is everyone using on the power supply; slo-blow, normal or fast blow?

TIA,
Bill
Slo-blow on the inputs as the inrush current may be times higher than the nominal current, especially when using torroidal transformers.
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Old 25th June 2018, 04:09 AM   #1057
Unkgd is offline Unkgd  United States
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Quote:
Originally Posted by fvzeppelin View Post
Slo-blow on the inputs as the inrush current may be times higher than the nominal current, especially when using torroidal transformers.
Slo-blow it will be, thanks!
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Old 16th July 2018, 11:09 AM   #1058
hadihf is offline hadihf  Pakistan
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Default My Scratch built DS Preamp

I get around 15V at TL750L12 regulator output with 17V input. Is this OK?

Best Regards
Farooq
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Old 16th July 2018, 11:28 AM   #1059
235 is offline 235
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Location: Australia
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Originally Posted by hadihf View Post
I get around 15V at TL750L12 regulator output with 17V input. Is this OK?
I noticed this on mine recently too and have been meaning to post a comment. I found that the TL750L12 was failing to regulate because it is oscilating at around 20khz. It needs to be loaded with 10uf, I used a tantalum.

Rob
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Old 16th July 2018, 12:18 PM   #1060
diyralf is offline diyralf
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Tantals are very good, but cause a lot of problems in old age. (Shorts etc.).
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