series input parallel output SMPS

A good switcher behaves as a negative resistance load to the input. Putting two of them in series will create interesting effects, for sure. It will not work, even with isolated supplies.

can see, that can NEVER work in the real world. "

Sure it can. All you need is to have a team study the problem, come up with a modification that makes it possible and then design a circuit that will make it possible. Piece of cake.

Then pay the fabrication costs for the new PC boards, after designing them of course, and then assembling this kludge in house depending on the design er of the SMPSes hoping they are deigned right and used good reliable compo nents. And only $ 14 each, oops, $28 each.

What could possibly go wrong ?

Relax, relax, you've made your case. Whenever there's a task that needs not-doing I assure you, you're gonna be my go-to guy.

There is no problem as long as you have adequate (input) capacitance between them. We do it all the time (by the millions). Galvanic isolation has nothing to do with it.

I sure am curious what mass market appliance contains switchers in series

NT

If you connect inputs in series and outputs in parallel and the inputs and outputs are not isolated from each other, you'll have a sturdy short-circuit somewhere.

ot-doing I assure you, you're gonna be my go-to guy. "

LOL. But you do get the point. With all this todo maybe those transformers in the units you have can handle more and you can just build your own. Real ly, the limiting factor is probably the chopper transistor. Put in a better one and made sure it switches right, ba da bing ba da boom. Well not boom. ..

You can probably use most of the original. the transformer is nothing but a coil of wire so between the transistor and rectifiers, it might not be so bad to just upgrade them.

That's a good point, I did take the time to check the part IDs on all the ICs and switches on board. The driver IC for the high current rails e.g. +3.3 and +12 can drive beefier devices than are used on the board, synchronous rectifiers so don't need to replace any diodes.

The other rails, +5 and -12 don't get as much demand in modern PCs so could likely leave those as is. I don't believe -12 is used for much of anything in fact but it's part of the spec so they have to include it.

Might just need to do a quick inductor/MOSFET/filter cap swap to push up to 200, the filter caps and inductors are thru-hole so that part's easy enough.

I think I'm going to give it a try in any case, it'll take the better part of a month for a higher power unit I need to arrive from China and if these can be easily modded for higher output power that'll be a good thing to know

Well I am the head n----r rigger (don't tell Black people I said that, it i s like hitting below the belt) and the King of clip leads, so...

Is there a drive optimization network on board you can modify for the new c hopper ? If so, great. If it runs directly off the IC or whatever then you have to choose the replacement with much care. If these things are used/sur plus there are probably better transistors available now, but don't spend t he rent on them. Heat might be a problem, that is why switching is so impor tant. I've seen 100 watt class D amps with NO heatsinking except the foil on the board. So this is doable.

That brings up the question of load variation, is it going to drive a motor ? Can the rotor be locked under certain conditions ? I'm sure you can do t he modifications to the current limiting, or putit in, but it still has to do its job.

If the rectifiers won't make it replace them of course. If you deem extra f iltering to be necessary just put it on the outside. Much easier and allows you to use a better quality cap. As big as you want.

Just some recommendations from an old gizmawhatchit builder. My latest proj ect is almost silly. I wanted a remote control tester. I know they have IR cards but f*ck all that. So I took and cut the board from the front of an o ld VCR and a part of a board from a TV with the standby supply. Put them to gether with solder and silicone goop, put in a regulator and a buffer for a light bulb, and have an output for a scope or use as a remote extender.

I know I know, I have too much time on my hands. Wanna gimme a job ?

Anyway, there is another advantage to modding them, you get twice as many a s you would running them in pairs, even if that got figured out.

Have fun. I would.

Doing it right will cost you less than the cost of the lab clean-up after the fire ;-) ...Jim Thompson

Sorry, I was confusing this thread (didn't notice the subject jump) for the one where JL and I were discussing heterodyning SMPSs. "Nevermind!"

No moving parts, just need to run a 95 watt max dissipation processor in a very tight enclosure. Disk drive will be solid state. But 120 limit doesn't leave much headroom for the rest of the hardware when it's running flat out, I'll likely need another 30-40 overhead for the small GPU in the expansion slot and a few tens more for the mobo and drive etc.

You basically just need all that power to dump it right back out into space via a hefty heatsinking system but that's the way it is...

You interested in relocating to Massachusetts? Not sure it'd be a good, ah, "cultural fit."

Doing a calculated inductor/MOSFET/cap swap on the high current rails seems like a plausible mod, I have to wait a while for the proper unit to arrive anyway. The synchronous buck controllers for +3.3 and +12 aren't being worked particularly hard and all the power-handling components except the MOSFETs are through-hole.

It won't be that big a fire, anyway.

Romneyville ? The state that had a balanced budget by raising every tax and fee possible except personal income tax ? The state where if you hold a CCW anywhere they dismantle your car if they catch you driving on their roads ?

Cultural fit ? The Kennedys ? (get in the caa nigaa)

I would last about five minutes and I'm White.

Yeah they tax you twice as hard but you can often get paid significantly more for the same job as compared to e.g. lots of places in the South so for many people including myself it ends up a net win. Sales tax is pretty easy to knock down by buying most essentials on Amazon and putting other expenses that you can't like gas on credit cards which dump reward points to your Amazon account.

There are always companies looking for even part-time skilled electronics tech/assembly work around here though, I'm looking at about

No, it's not a win. I've been on both sides of that fence. It's not even close. The pay in blue states is somewhat higher than red but the cost of living is fantastically higher in the blue. It's not just taxes, either, though that's huge.

There are at _least_ that many around here. There are a third of that number in the little city (pop 35,000) I work in. I think my employer has at least five (maybe more, haven't checked) open reqs for engineers. No part-time, that I know of. I get emails from Glassdoor about open position in the area constantly (half dozen a day).

It's fantastically expensive to own even a medium-sized home in the suburbs here and pay Boston-area real estate costs and property taxes and all that stuff. So don't do that, duh! Ain't no law says you have to.

You don't own a mirror, do you?

No, you just want to marry yourself.