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How about a teeny tiny power supply?? Answered

I've seen some pretty good power supply projects on here. Here's a challenge: Make a 5 to 12 volt power supply that can fit into a 1 cubic inch space, of any dimensions, i.e. 1"x 1" x 1" or 1/2" x 2" x 1", etc, including any enclosure. It must put out at least 300ma sustained and must have a fairly smooth voltage regulation for use with other electronics (of course). It must have clear schematics without the use of special programs to view, i.e. it shouldn't be in an eagle format or rather can be viewed with paint, or any of the other picture viewers. It must be powered from the mains and NOT use a microcontroller or any custom chips. The smaller it is, the better, and less than 1 cubic inch is excellent. I've seen real genius on here. Is this genius ready to try this?


Well, I took the advice of Westfw and bought a couple of suppies he mentioned in one of his posts. I bought the 9v supply (2). They aren't quite as small as I would like, and the spec sheet talks of added caps (I'm assuming they are mostly optional), but they can be fit into a configuration that will work. Thanks very much. On another note, a switching supply is something I'm unfamiliar with (well, at least the makeup of it), and a diagram/explanation/schematic would be helpful if anyone has the time. Basically, if it can be built with off the shelf components and commercially available in the size that I just purchased, then miniaturization is the only step I need to consider and hack together.

How about 8 pA at 50 mV from a single wire?

It doesn't quite meet your specs, though:
  • Each wire is 4 µm diameter × 200 µm long (~2500 µm3)
  • One cubic inch is 15,625×109 µm3
  • You could (in principle :-) pack 6.25 billion of these little generators in there.
  • In series, that would only provide 50 mA.

Since you're thinking piezo... What do you suppose using a crystal oscillator can do, and how would you put it to work to make power for you? Its another path to look into.

Would you be willing to go with a "online regulator" ?? one which is transformer less ?? and keep in mind while these work and they are small, the actual potential difference between a earth ground and your 5 volt line is 120 Vac but the 5 volt line positive and negative is 5 VDC ... So care would need to be taken to ensure that no one is exposed to potentially lethal voltages ...

It will be housed inside a plastic case anyway, so exposure to voltage isn't a problem. A small enough layout can also be encased in resin so long as the heat dissipation isn't a problem.

Go for it! Mind you, now, there is (as I recently found) commercially available power supplies in a 4 pin PCB package that do this. BUT, if you can MAKE one and document it, then everyone benefits, not just me.

It's easier to just buy a 5 volt PSU, I have found a few at the E-waste recycling centers and they are tiny 1x1x1/2 they offer five volts output at 1 Amp and 120 to 240 VAC input, and they are free from the e-waster centers if you ask nice..... They even have slightly larger units 2x2x1/2 that output 2 to 2.5 amps and they all have CSA, UL, VDE, BS, ITE and other safety rating on them so they shouldn't kill you, and most designs have been hi-pot tested so if there is ever a surge you don't get killed either..... Not to mention finding items like inrush protectors and custom wound transformers in small quantities can be a real chore if not down right impossible (( just ask Hammond transformer how much it costs to wind one transformer , is scary, sure it's cheap if your looking at thousands but the set up fees will detour most hobbyists )) But if your just looking for some thing to power say a few LED's you could use a simple capacitor since they act like resistor on AC circuits ... Very small and simple but it's not 5 volts output .... What are you looking to power ??

This sounds really promising, but what are they from? I've got enough e-waste I can get a hold of to scavenge parts for years. The premade stuff is also nice to be able to grab and go, but, I would still like to see an 'off the shelf' DIY if at all possible. If you can tell me where these PSU's are coming from, that would help. Oh, and the Idea is to eventually put it together with a wireless camera inside a night light housing, kinda the ultimate nanny cam. I used to put stuff like this together for folks, but anymore the demands for really small space requirements is kind of boggling my mind. Sooo, I'm asking around to see if someone has an idea or schematic, or whatever. I'm kinda old school and I don't do micro-processors, etc very often, I think their use in most projects is overkill. I made a discrete component (using 74xx) infrared gun aiming device about 15 years ago to zero in a BB gun on the rats out in the barn. Worked really well, using straws and small lenses in a matrix. It was fun.

Cell phone chargers these days seem to be about 2*2*0.75 or so, and supply 5V at 500mA or so. Here's a picture of two. Note that a significant portion is taken up by fuse and "noise filter", and the largest components are things that might not shrink very much (Actually, the input filter cap might be smaller if you give up "universal" (240V) input.) Note that 12V@300mA is significantly more power (3.6W vs 2.5W output.) There are some SMALLER power supplies aimed at the <1W "standby power" for larger devices to make them greener; 5V@50mA or so... (Personally, once your wall-warts get small enough to fit in a socket or power strip without interfering with the neighboring sockets, there doesn't seem to be a lot of motivation to make them any smaller. And we've pretty much already reached that point.)


I think the universal (240v) will be key to miniaturizing the whole thing, by removing it. Filtering is really not an issue after the main cap smooths things out, so it can be minimized. The camera I'm looking to use is only about $30, give or take, and if I burn one up in the process, I can buy another one.

I know what you mean about the size and motivation. I've already put this stuff inside those 6-outlet adapter boxes, like the one used for the LED light project on here. THAT was easy. This is a motivational factor. Hey, anyone here work for the CIA?? =)

Note that the filtering I'm talking about is EMI filtering, not ripple filtering. The main cap is going to do particularly poorly at filtering the EMI at switch supply frequencies (which is why all those little wall warts even contain the EMI filter...)

I see. Hmmm. The PS in the wall outlet I made must have already had that built into it. The camera works great, without any distortions.

And maybe before it get overcomplicated, companies like hammond make some very small transformers, which while they are not as efficient, the small amout of extra heat will be welcomed in a outdoor camera enclosure to reduce fogging, frost buildup and most CCD cameras don't like operating in the cold....


The smallest of the 60Hz transformers from Hammond that you mention is already up around 1.9 in3. You just can't DO 2W or so in a cubic inch at 60Hz; you have to use switching technology (at a much higher frequency, which permits smaller magnetics.)

I realize that, however with that said maybe they are able to build around a 1.56x 1.88x 0.65 transformer just to simplify it, because you shouldn't just open a switched mode supply and start removing the EMI / RFI filtering because it doesn't fit, it is there for a reason and if you start looking at octaves these small harmless power supplies can cause all sorts of interference, when altered, and just because it doesn't bother a coaxial cable line carrying a video signal doesn't mean it's not broadcasting some octave on say some thing like Sarsat's frequencies ((( Chinese made DVD players have been found by search and rescue and this signal was coming from the clock on a micro ))) And hammond was the fisrt company to come to mind, mainly because they are easy to buy from and easy to find in most stores, there is other compaines like ATC frost (( they will wind you any thing , but it's not cheap )) , Sola, GE etc.... Also I was trying to kill two birds with one stone because CCD's used outdoors either don't work or don't work very good in the cold so they end up needing a heater which is just more power from a Switched mode so it then becomes larger, when the heat from a transformer would be enough with proper sealing and insulation ...

Here's another. I think this is the charger for a Motorola Razor phone, so it should be easy to find. AND I think the actual components here are well under a cubic inch....


Well, except for the actual transformer, everything else could be SOT packaged and quite small....well, even though they have gotten many capacitors way down in size, they are not quite SOT, as far as electrolycs, but they are close :-)

Surface mount is probably the ONLY way to go. I've worked with some of this stuff, and my eyes stay sore when I have to replace components on boards. At least with surface mount I've seen caps made from the excess copper on both sides of the board that was left un-etched. Even coils.

Unfortunately, when it comes to things that operate from the AC lines, there are safety issues (and regulations) that end up controlling some minimum distances (for instance, they make special "stretch" 0.4inch DIP packages for optoisolators to meet the requirements.)

For scratch-built, as opposed to module I mentioned elsewhere, there is a reference design for a 5W charger from ON semi that could probably be a bit smaller for the ~2W supply mentioned here and 110Vac-only input, and if you eliminate some of the "niceities." There are some other neat app notes associated with the chip in question, and other vendors have similar chips.

Yes, I've been concerned about the isolation aspect. The fix is to spit the PCB into two sections inside the light housing (for homemade circuits) and jumper them together to provide adequate distance from the input to output sides.

THIS looks good. I think I'll order a few in different voltages for other projects too. I'll try to document my process and redo the six outlet mod with a camera and document that too, and put them up on here. It beats buying the typical (ho-hum) 'plush toy' camera, which costs an arm and a leg and sometimes a few extra fingers like the clock radio cam.

I still want to build the door knob camera =) as heard on M*A*S*H.

cell phone chargers. some of them are inside way smaller than the plastic case they are in. the lightweight ones (switching mode) often give good stabilization you can get em free from people whose phone died etc

Would you be talking about the wall warts or an actual charger built into the phone?

Agreed - those or the chargers for blue-tooth ear-pieces.

could one not use a pico psu? its a tiny psu that is used with tiny embedded computers. I don't know if it will work for your uses, but its worth looking at.

After looking up the pico psu's through Google, no, it won't work. They all seem to be DC-DC converters. I want to see an AC-DC type.