Higher current voltage doubler

[Mick Bailey]

The Godlyke Iso has decent current output listed in the specs - maybe uses a switched inductor rather than charge pump? Does anyone know what is used? Looking at doubler/programmable IC specs I haven't come across any step-up devices that handle this kind of current. Plenty of high-current step-down, though.

Godlyke Iso-Pump Voltage Converter | Godlyke Power Pump

EDIT: just seen the LT1372 which looks like a pretty good candidate.

[Mick Bailey]

Here's an update;

I bought some CS5173 devices and breadboarded an 18v converter. It works superbly and I can pull 500mA. These devices operate differently to what I'd assumed; You don't get a doubler - you preset the output voltage and the device maintains this regardless. So if you want 9v to 18v a simple resistive divider across the output sets the output voltage via a feedback loop where you need it. Now, if the input voltage drops, it maintains the output voltage and compensates by pulling more current from the input. For such a tiny IC I think it's pretty impressive. I'm mixing SMD and through-hole right now, but the circuit could be made really tiny with full SMD. The inductor is the only thing that's a little clunky - it needs to be relatively high current at 2A. All rather inexpensive, too.

[darkfenriz]

That's a one nice chip you have there.
I'd expect something along the MC34063 lines if that was a mass/asian product, but that's just a guess. Your chip looks 100 times less headache in comparison.

[Gnobuddy]

...CS5173 devices...

560 kHz? Wow. I hadn't realized that today's switch-mode power supplies had switching frequencies all the way up in the old AM radio band!

-Gnobuddy

[Justin Thomas]

No wonder I can't find a place in the house to play my @$&#ing Tele... dammit.

Justin

[Enzo]

SMPS even run into the Megahertz these days.

[Gnobuddy]

SMPS even run into the Megahertz these days.

Crazy, right? I remember them whistling at a few kilohertz (well within the audio range) not so many years ago. I wonder what's allowed the rapid frequency increase, maybe faster power MOSFETs?

I saw some old (analogue, big-iron) power supplies recently, cased in a hefty steel box measuring maybe 14 in x 8 in x 8 in, and weighing maybe 15 - 20 kg (33 - 44 lbs). They were rated for 12V, 6A DC maximum output (72 watts). Today a laptop SMPS the size and weight of a small bar of bath soap puts out more power, and it's cleaner and better regulated, too. Amazing!

-Gnobuddy

[Enzo]

Everything has gotten better, and advanced the art.

[Mick Bailey]

Hard to believe this little chip will switch 1.5A at that frequency. It will also do split-rail supplies and much more. Here's how my (slightly clumsy) prototype worked out;

[nickb]

I feel kinda mean posting this after your hard work and you did a nice job too... but...

You might want check these out. 150w! I used a few for battery powered portable amps. It could save you time and effort in the future. Crazy cheap.



Need 350v 40W ?





Smaller & lower power?

[Mick Bailey]

Thanks for the suggestion. The idea was to replace the 240v mains supply in a couple of pedals, so they need to be small. The smallest unit doesn't look like it would give 9v to 18v conversion at 500mA (actual draw 460mA). I'll order some of those high-current units as I can use them in another project. You have to laugh at how cheap these things are.

[Gnobuddy]

You have to laugh at how cheap these things are.

The flip side being that traditional 60-Hz transformers are very rapidly headed for extinction, at least in the sizes where we might be interested in them. We already have to go to speciality sources to find transformers that work with valve-friendly power supply voltages and output impedances; what happens when E-I cores are in such small demand that they stop being manufactured?

A bit closer to the topic of this thread: a lot of HP inkjet printers use a 32V DC power supply. Some of these power supplies have both +16V and +32V rails. Most of the smaller ones have the DC output isolated from the incoming (2-wire) AC mains. I find these HP inket power supplies quite frequently at local thrift stores, and they tend to be very cheap, because nobody wants them.

Well, almost nobody. I've successfully used these as +/- 16V DC supplies to run op-amp based circuitry. They work well, with just a little extra RC filtering to remove low-level switching noise on the supply rails. They might be a good way to power guitar FX pedals too, either using the +16V rail, or you could custom-design your own pedals for either split +/- 16V rails, or a +32V rail.

-Gnobuddy

[Mick Bailey]

I have quite a few players running their pedal boards off laptop power supplies. I run them into a distribution box and add extra linear regulators to give 12v and 9v outputs. The isolation from incoming mains and ground on some (though not all) laptop supplies means no ground loops. The big advantage is they can carry a spare at low cost and they're much more robust and better quality than most stompbox supplies. I always check though that the outputs aren't elevated to 80v above ground due to the internal EMI cap if one is fitted.

A while back I dropped on a batch of new medical-grade supplies. Don't know what they were intended for but there was no noise at all on the output and inside they were built really well with the highest possible parts quality, construction and screening.

[nosaj]

I have quite a few players running their pedal boards off laptop power supplies. I run them into a distribution box and add extra linear regulators to give 12v and 9v outputs. The isolation from incoming mains and ground on some (though not all) laptop supplies means no ground loops. The big advantage is they can carry a spare at low cost and they're much more robust and better quality than most stompbox supplies. I always check though that the outputs aren't elevated to 80v above ground due to the internal EMI cap if one is fitted.

A while back I dropped on a batch of new medical-grade supplies. Don't know what they were intended for but there was no noise at all on the output and inside they were built really well with the highest possible parts quality, construction and screening.

Medical grade is the best as you don't want any sparks should a patient be using oxygen.

nosaj

[Enzo]

More than that, you don't want ANY leakage current on the unit that might interfere with a pacemaker or sensitive monitoring equipment connected to the patient. And of course maximum protection from the mains.