hi guys
just a quick question ...cud it be possible to change the lm7815 and lm7915
with lm317 i like to be able to adjust my power supply so its so accurate as possible.
with out do to much change on the orginal psb.??
Tom
just a quick question ...cud it be possible to change the lm7815 and lm7915
with lm317 i like to be able to adjust my power supply so its so accurate as possible.
with out do to much change on the orginal psb.??
Tom
Tom,
The power supply PCB that you will soon be receiving in your PCB kit is fully adjustable from +/-9 volts to +/-24 volts.
Details are here: Dropbox - SERIES_VREG_PWR_SUPPLY.zip
i see in the bom list that was lm7815 and 7915 has it been chance in the later version?
if its fully adjusteble its just great...
because i see many has mention before they had uneven voltage in each rails...
thanks for replay
if its fully adjusteble its just great...
because i see many has mention before they had uneven voltage in each rails...
thanks for replay
in the schematic its only transistor in the new layout no regulators.
and the first layout i see in this tread was regulators lm7815andlm7915
thats why i asked....
but since all things are changed for the better i am happy about it.
thanks anyway
I have another question.
I like to have a mono out,
Cud I take the signal strait from the output and just as a summer to make mono.. Using ina134 for example.??
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I like to have a mono out,
Cud I take the signal strait from the output and just as a summer to make mono.. Using ina134 for example.??
����
I never needed this. But I guess you could just use a standard summing amplifier. And you could use LM4562 here, as well. And you might want to read the chapters about mixers in Small Signal Audio Design.
How much heat does the LM317/337 produce with a 18VAC transformer? I'm assembling my preamp in a 1U chassis and an going to need to mill the heat sinks down to fit under the cover. Will 1.25" tall heat sinks work here?
I think voltage drop X(times) current used is more important, not the transformer secondary voltage.
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.
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.
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 🙂
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.
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
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.
My Scratch built DS Preamp
I get around 15V at TL750L12 regulator output with 17V input. Is this OK?
Best Regards
Farooq
I get around 15V at TL750L12 regulator output with 17V input. Is this OK?
Best Regards
Farooq
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
