Brute-force linear supply manufacturer?

Mouser carries a few from International Power; look at the bottom of

Googling finds similar parts from Powervolt,

I don't know if either of these are any good or not, just that they exist. Both of them seem to have three taps for each input voltage (-10%, nominal, +10%) so you can adjust the output a little at install time.

Standard disclaimers apply; I don't get money or other consideration from any companies mentioned.

Matt Roberds

Try Tessco.

tm

Hello Tim

Ismet

As always, there's plenty of companies in the far east (some in China, but for this type of product also India) willing to build something similar for a fraction of the price, but then you'd better IWT and HI-POT them just in case (and, especially if it's India, still treat the secondary with the same respect as the primary).

Regards Dimitrij

Yes, but you have to spend money!!!!!!!!!!!!

THey are pretty much up there due to the transformer needed.

Jamie

That's not a linear supply!

Let me clarify: Brute force. Unregulated. Some of you got that -- good.

CHOKE INPUT. Meaning that there's a filter choke and a filter cap in there. I've seen them, I'm about to canvass some ex coworkers to see if anyone will look at labels.

Wow, choke input--this is for a steampunk rock crusher project, right?

Cheers

Phil Hobbs

- good.

I think the only time we did something like that we made our own. (Variac->rectifier->big C -> magnet coils..) (I don't know if there is an inductor..)

If it's a hard part to find then making your own has some advantages.

George H.

It's for a last-minute change to a project that drives motors and thus really should have had an unregulated capacitor-input supply from the first, but was painted into a corner by having no room for anything but a switching supply. So lots and lots of extra work went in to pamper the supply. Now that all that work has been done, the customer has decided to put the supply elsewhere in the product, and there's all the space in the world. Alas, they were so adamant before that I did not think ahead, and we'd need some (quite minor, but still) board mods to handle the entire possible input voltage range from an unregulated cap-input supply.

I've seen 28V choke-input unregulated supplies as recently as a decade ago. In fact, I've lugged them around labs quite a bit. I just don't remember who made them, nor do I have any idea of how available they are now.

Maybe talk to companies like this:

Also Power-One and others. Most likely the only chance is that they make a similar product for someone else already. Because in view of today's copper and labor prices there ain't much out there in Goliath-sized linear supplies anymore, it's all switchers.

Of course, with you being the PID-guru, you could design a switcher around a Cypress PSoC or similar that behaves like ye olde swinging-choke supply :-)

Then it technically is not a linear supply.

?????

Choke input just means that you use an L-network filter instead of a pi network, which gives you an output equal to the average value of the rectified sine wave. In the limit of large inductors and ideal diodes, that's sqrt(8)/pi * Vrms, rather than sqrt(2)*Vrms for a capacitor-input (pi) filter.

sqrt(8)/pi ~=0.9003 and sqrt(2) is of course 1.4142+, so using a choke-input supply reduces the DC output by a factor of 2/pi ~= 0.637.

Same kind of supply, just a slightly different filter.

Cheers

Phil Hobbs

All well and good Dr. Phil but that would just be known as a rectifier and filtered, unregulated supply. Add a linear regulator and now you have a linear supply. Just a terminology nit, I know. But it may make searching a bit better.

Linear is as opposed to switching. If you put a 7805 on the output of a switching supply, it doesn't become a linear one.

Cheers

Phil Hobbs

If the choke is a swinging choke where the inductance changes depending on current it is no longer linear :-)

Of course, if there's diodes in it then it isn't linear either

Since Max Plank none of this could ever be linear in the first place, even if it all was just a bare wire, because his quantum theory says everything is quantized.

And then of course there are those nice linear diodes. ;)

Cheers

Phil Hobbs