I have some that I've used for many different projects, but nothing with high gain like a phono pre. Never had an issue with noise though. The ones I have clean up well with a little filtering on the input/outputs.
If you want to give one a try, let know. I still have a few somewhere.
https://www.mouser.com/ProductDetai...BWR-15-330-D12A-C?qs=b13bmSh8y6xAobPTcN9SYQ==
More regulators require more overhead than the SMPS can provide. Not that it matters a whole lot, but the double LM317 arrangement will also be less noisy (though the cap multipliers certainly do the trick.)
I'm just cheap and want to sever the umbilicus!
I've been using a 24VAC wall wart to power my pre with great success. The AC wall wart (of your choice) feeds an adjustable 317/337 based regulator. This can also be used with a split tranny. The values can be easily changed to get any +/- that you'd want. I'll send you the gerbers if you want them. Note that the recitifer stage ground ties back into main ground at the source point to minimize noise.
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@audiosteve: I've tried that and it oscillated. This can happen if the currents drawn by each rail are unequal.
Seriously? What oscillated? I've never had that problem. That makes no sense. I doubt the issue was with the topology. Please eelaborate if you can. Thanks.
Something like this, just use your favorite LDO
regulator instead of the 7815, and either replace
the TLV431 with a TLV431H or a TL431 and recalculate
the resistors.
From the bar.
regulator instead of the 7815, and either replace
the TLV431 with a TLV431H or a TL431 and recalculate
the resistors.
From the bar.
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create .zip archive file, put forbidden file into .zip, upload .zip to Forum. It works. See attached.
HI Jan,
Yes, I expected you might be too busy, not interested enough or both but expectations are often wrong so I had to ask at least. Thanks for taking the time to reply.
This is why you can't use LM317/LM337 as a rail splitter -- as the load on one changes, the voltage on the other moves in the opposite direction. It's a simple simulation changing the value of a resistor to mimic current drawn:
The LM317 needs a minimum load of 5mA to remain stable. This results from the change in transconductance of the pass transistor with current,
The LM317 needs a minimum load of 5mA to remain stable. This results from the change in transconductance of the pass transistor with current,
Attachments
RJM1 - What was that .rar file you posted? VLC tries to open it but can't. Not sure what to use. Thanks
RAR file was deleted as it contained the wrong .jpg.
This was not updated because the correct .jpg did
not cotain any useful information.
This was not updated because the correct .jpg did
not cotain any useful information.
One approach could be to use a DC/DC converter to take a single DC voltage and turn it into a ±15 V supply. For example the Mean Well DPBW03F-15 or DKM10E-15. I use the DKM10E-15 in my HPA-10 and it's hard to argue against its performance.
I have noticed, though, that some AC/DC switchers inject quite a bit of mains hum into the circuit. You may have to try a few to find one that works well.
Tom
I have noticed, though, that some AC/DC switchers inject quite a bit of mains hum into the circuit. You may have to try a few to find one that works well.
Except you can't buy those anymore. At least not in North America. I think they were phased out due to their no-load losses. Many years ago I measured the power consumption by various wall warts. Many of them used a few watt even with no load connected. That won't meet modern energy efficiency standards, so they're practically banned for all but industrial uses. I know because I really wanted to use a classic wall wart with the HPA-10. I asked the main distributors (Mouser, Digikey, Future, et al.) and none of them could deliver a simple wall wart. The ones that remain show as "for industrial use only" on the distributors' websites.
OTOH, those switching spikes are pretty easy to filter out. Also, switchers nowadays tend to feature spread-spectrum clocking and all sorts of neat tricks to reduce noise (and EMI).
Tom