Wallvart PSU? Is there a good design out there?

Hi Guys,

I'm using the FCUK mini power for my circuits (mostly "transformerless" and "tubeless" designs), because they don't need that much power.

Everything is fine, the only problem is that it is really really really hard to find 12V AC wallvarts in Hungary...it is almost impossible

My questions is that is there a design / schemo out there for a good, not noisy PSU, with a 15-18V DC input and a bipolar 15V output?

Found this :

You probably know about this but hey what the heck, its 12V but you have ALL the info about this kind of circuits here :

http://www.musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1670&VPH=754

> Found this :

That will split 18V DC into bipolar +/-9V DC.

Since many "bipolar 15V" plans will work just fine at +/-9V (at somewhat reduced maximum output), this sure is the simple way to do it.

Converting single 18V DC to full bipolar +/-15V implies a voltage step-up. This usually involves converting to AC, transformer or diode-pump to change voltage, and back to DC again. Not simple; maybe a real distraction from your actual project.

There are small epoxy lumps which take one DC voltage and output one or more different DC voltages. "DC-DC converters". One old mass-application was ethernet cards, which needed +/-9V power but only had 5V feed. Similar things made for powering +/-15V signal preamps in 5V digital systems. 5V is most common, 48V (telephone switching) is next most common, but 12V converters exist and may have a range to 24V. I was just looking at MeanWell's catalog. Jameco in the US tends to have stock of many types. But if a basic 12VAC or 24VAC wall-wart (widely used here for burglar alarm power) is not readily available there, then these other ideas may not help you.

Thanks.
I'm still looking for a good solution for my smaller, 1U projects.
I have to find something.

I'm using MeanWell switchin PSU-s with my modular synths, without problem.
Found a few small PSU-s in the Meanwell site, seems small enough for me to build them inside a 1U case, and they give me +-15V with enough juice.

Any experience with these PSUs?

http://www.meanwell.com/webapp/product/search.aspx?prod=net-35

The Link doesn't work but I build my own PSUs. Just because i wanted to know how it works. I do my own PCBs and etch them in my Bathroom

Same bathroom etching method here

snaper said:

Thanks.
I'm still looking for a good solution for my smaller, 1U projects.
I have to find something.

Click to expand...

How much current do you need? I cooked up a little switcher unit that takes in +9V and outputs ±15 V (after linear post-regulator, which you can bypass) as well as +5 V and +3.3 V. It'll do half an amp on each 15 V rail.

I'm using MeanWell switchin PSU-s with my modular synths, without problem.
Found a few small PSU-s in the Meanwell site, seems small enough for me to build them inside a 1U case, and they give me +-15V with enough juice.

Any experience with these PSUs?

Click to expand...

At the day job, we've basically blackballed the Mean Well switchers, at least the hundred-ish watt switchers. Why? Because while they might Mean Well, they don't Work al that Well.

-a

Can you elaborate on the issues you have seen with the Meanwell modules, Andy? I am involved in a commercial project where the PM20-24 (approx 20W) has been specified, mainly because it is carried by so many distros, and we're nervy about designing in a part which is awkward to source. Certainly, the ripple + noise spec for the MW is inferior to some other modules, but the design has linear vregs further upstream, so this shouldn't be a factor. Are the MWs one of those SMPS modules which have a habit of inexplicably failing? I'm surprised if this is the case as I'd think they wouldn't be so ubiquitous.

Andy Peters said:

snaper said:

Thanks.
I'm still looking for a good solution for my smaller, 1U projects.
I have to find something.

Click to expand...

How much current do you need? I cooked up a little switcher unit that takes in +9V and outputs ±15 V (after linear post-regulator, which you can bypass) as well as +5 V and +3.3 V. It'll do half an amp on each 15 V rail.

I'm using MeanWell switchin PSU-s with my modular synths, without problem.
Found a few small PSU-s in the Meanwell site, seems small enough for me to build them inside a 1U case, and they give me +-15V with enough juice.

Any experience with these PSUs?

Click to expand...

At the day job, we've basically blackballed the Mean Well switchers, at least the hundred-ish watt switchers. Why? Because while they might Mean Well, they don't Work al that Well.

-a

Click to expand...

Hm...0.5A would be enough I think for me / rail...