Oh goddammit...

[c4757p]

Hmm, this regulator's not working quite right. Let's see what's wrong with it.

Oh, the current limit's kicking in really early in the cycle. Well brain, what's the stupidest idea you can come up with? (Brain: "Derrrrp.... uh... short out the sense resistor and see what happens?") OK! Here I go!

Ow! Shit!

(My best guess is that I miscalculated the inductance by an order of magnitude or so. Looked like saturation, but that core doesn't saturate south of six amps. Whatever it is, I'm sick of Mr. 34063, I'm doing something else tonight!)

[dr.diesel]

Stuff the magic smoke back in and just glue the lid back on, good to go!

[c4757p]

It just occurred to me that the 34063's tendency to self-destruct like that makes it a pretty poor candidate for use in a kit, which was its intended purpose. LM2575 it is, then. It's a bit more expensive, but works better and is more robust.

[dr.diesel]

Which kit is this for?  Don't you have 2-3 kits running now, starting a business are you 

[c4757p]

The only other one I was starting was an electronic load a while back, which quickly became uneconomical due to the need for an engine block-sized heat sink. This is for the function generator. I need ±15V rails and a +5V rail, all relatively beefy. The plan was to use any generic 18-24VDC adapter, with a linear reg down to 15V, an inverting switcher to -15V, and to-be-determined down to +5V (still not exactly sure how much load there will be on that rail).

[kxenos]

In my workshop, we could easily with the seamless teamwork that we are known for, explode the IC, both caps and pretty much set half the lab on fire. I have a colleague that can explode even the coil core for christ's sake! 

[Phaedrus]

Design your DC load kit to mount a standard Intel heatsink. Everyone has one of those pieces of crap laying around, or can get one for <$10

[c4757p]

In my workshop, we could easily with the seamless teamwork that we are known for, explode the IC, both caps and pretty much set half the lab on fire. I have a colleague that can explode even the coil core for christ's sake! 

This core is designed for pretty hefty applications. I'm sure that if I were using it near its design power, I'd find a way to do that too.

Design your DC load kit to mount a standard Intel heatsink. Everyone has one of those pieces of crap laying around, or can get one for <$10

Yeah, that's a good idea. Much better than "short out the sense resistor", which is probably the best idea I've had in the past hour. But I've pretty much completely lost interest in that one. Loads are all the hell over the place and way too simple. Hell, when I need a load I grab a fistful of resistance wire I ripped from a toaster.

[lowimpedance]

You need a tube of superglue  , then do a rain dance and pray.
--------- Or just frisbee it out the window.

[Corporate666]

Damn, you harcore!

That is some pretty adept finagling of parts on (what looks like?) a giant copper sheet.

Well done - until it went south, of course

[Dave]

--------- Or just frisbee it out the window.

I say
WIDLARIZE IT!

[c4757p]

That is some pretty adept finagling of parts on (what looks like?) a giant copper sheet.

Copper-clad FR4. One of the things I wanted to measure was the output noise, so I needed a layout at least as good as whatever I could throw on a PCB.

I say
WIDLARIZE IT!

Sounds like a good plan.

[Phaedrus]

In my workshop, we could easily with the seamless teamwork that we are known for, explode the IC, both caps and pretty much set half the lab on fire. I have a colleague that can explode even the coil core for christ's sake! 

This core is designed for pretty hefty applications. I'm sure that if I were using it near its design power, I'd find a way to do that too.

Design your DC load kit to mount a standard Intel heatsink. Everyone has one of those pieces of crap laying around, or can get one for <$10

Yeah, that's a good idea. Much better than "short out the sense resistor", which is probably the best idea I've had in the past hour. But I've pretty much completely lost interest in that one. Loads are all the hell over the place and way too simple. Hell, when I need a load I grab a fistful of resistance wire I ripped from a toaster.

Give me a 1500W/140A electronic load with <0.2% accuracy. That's a kit I would buy. 

[codeboy2k]

It just occurred to me that the 34063's tendency to self-destruct like that makes it a pretty poor candidate for use in a kit, which was its intended purpose. LM2575 it is, then. It's a bit more expensive, but works better and is more robust.

It didn't self destruct... I am sure you helped it along but the LM2575 is a good part... really easy to get working, so in a kit it's possibly the best choice..

[Stonent]

If treated poorly, signal diodes become LEDs.  I learned that at about age 11. 

[madshaman]

All I want to say is: nice destruction!!!  :-)

[owiecc]

If treated poorly, signal diodes become LEDs.  I learned that at about age 11. 

A friend had a potentiometer turned to white LED. Power dissipated was just enough to make it shine but not high enough to burn the damn thing.

[sprocket]

Hmm there must be a marked for flakjackets, kevlar helmets and ballistic eyewear designed for electronics geeks. With schrapnel wizzing by and what not.  O0

[c4757p]

If treated poorly, signal diodes become LEDs.  I learned that at about age 11. 

It was a nice yellow-gold

[dr_p]

some time ago I finished my design then noticed an electrolytic has getting hot. Also slightly bulged, then a bit more, then seriously bulged, then OH SHIT.
Reverse polarity...

[ciccio]

It was too  nicely assembled.
The IC decided to puff the magic smoke so you could post a photo and everyone in the forum could be jealous ans feel unprofessional...

[c4757p]

Don't worry, when I get the 2575 finished I will post a picture of that and you can feel better about yourself again Its pinout isn't quite as conducive to a nice layout that looks like the schematic.

Hmm.... having a bit of trouble getting more than about 150 mA out of it. It's like I suddenly forgot how to build switchers...

[c4757p]

Ready to feel better about your circuit prototyping technique? Here's my LM2575 circuit

Turns out the bloody inductor was saturating after all... at 800mA! (I confused myself by misreading the scope scale on my current probing setup and didn't see what was really going on.) Turns out I've got a bag of dud toroids - some work just fine at high power, and others clearly saturate if you sneeze on them. (Explains a few other switcher mishaps I've had, too....) I didn't want to fart around with that, so I grabbed a 100uH 3A Murata out of the bin. Works fine now. Forgot I had those inductors...

Clearly, you get what you pay for.

[dr_p]

Turns out I've got a bag of dud toroids - some work just fine at high power, and others clearly saturate if you sneeze on them.

I found that some toroids are iron while others are ferrite.

[c4757p]

These are almost certainly all ferrite. I am not sure what can go wrong in the production of a ferrite core to reduce its saturation flux to about one tenth - I know just over "nothing" about magnetics - but they all appear to be the same type. Some work, some don't. I may break open one of the bad ones to see if there's something obviously amiss.