Need the topology for a current to current SMPS, not voltage to voltage SMPS

I stopped keeping such stuff after moving to California, where houses neither have basements nor attics.

You can be lucky not to have gone to school in Europe. There, the bureaucrats change units at a whim. First we learned kilopond, then that went out of fashion and Newton was en vogue. Even worse with pressure: Torr, then it was changed to atmospheres, then it was change to bar, then it was changed to Pascal. Crazy.

Now that I moved to the US and workd in some fields such as aerospace where metric isn't used I became used to imperial units. Not as easy in the math but the nice thing is that the units never change.

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Joerg
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I think the easiest way for the large compliance range is a flyback that measures the input current and regulated to an output current of desired (or programmable) magnitude in relation to the measured input current. Then it's input voltage will automatically adjust to what is needed, without wasting anything other than the losses in the flyback. Of course, the 95% requirement pretty much mandates a recuperating winding so it'll be a custom transformer. No flaring off of the leakage inductance spikes in snubbers or zeners.

Washington "gets" about 50% more out than what comes in :-(

[...]
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Joerg

In them days people still knew how it's done. I bet it is possible to copy a Model 59 using semiconductors, such as dual-gate FETs. But there is no market. Most kids these days don't have a clue what a dipmeter is. In fact, whenever I showed up with my Heathkit 1250 the only folks who knew what that weird thang was were ham radio operators well past the age of 50.

Nowadays you can easily achieve that precision: Use the Model 59 and run the spectrum analyzer in parallel, using a loop antenna underneath your work bench. Make it snap to the strongest signal. BTDT. Now, about changing the display of the spectrum analyzer to megacycles ...

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Reply to
Joerg

I also have a Keithley 405 "Micro-Microammeter" (most sensitive range is

100 fA FS). Not to be too pico, er, picky.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

I can raise you one more. Here is an "entertainment system" we have at the entrance:

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It essentially contains the first IC in the world. The tube contains three sections, four resistors and two capacitors (it's all inside the glass). IIRC my grandpa bought it in 1927. He was always the early adopter when it came to technology.

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Reply to
Joerg

Wow. I guess the Blaupunkt/VW approach to product obsolescence started early--filament blows, replace the whole radio. ;)

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

Agreed... a useful tool, sadly almost forgotten.

I've been tempted to (re)build a dipper, using a "lambda diode" arrangement (two JFETs or a JFET and a bipolar) to simulate a classic tunnel-diode oscillator.

That's one of the more useful applications for a P-Touch labelmaker :-)

Reply to
David Platt

I can remember caps (probably out of obsolete equipment at the time) being marked in MMF.

I ran across an old design for an optical lever amplifier that used OC71 transistors. Had the misfortune to come into about 1,000 of those things as a wee lad. They almost put me off semiconductors.

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25mW maximum Pd (confused me when I ran into some hydrogen thyratons that were 40MW)

-5V maximum Vce (minus plate voltage, what insanity is that?

Beta of 50, not great, but not terrible.

IIRC, leakage was horrible, uA at room temperature, and rapidly increasing if you approached that 25mW maximum Pd.

Reply to
Spehro Pefhany

Then you aren't old enough. Our forefathers measured capacitance in jars. Later in centimeters.

They actually brought me to semiconductors. I got a bag of hearing aid size OC transistors of dubious quality, brand name "Fell-of-a-truck". Some leaked terribly, others had other blemishes, but it cost only the equivalent of a couple of Dollars for dozens. Now I could build stuff that ran on a totally exhausted flashlight battery. In Europe they were called "Lady Cells" for some reason, had 3V when fresh, were used to power flashlights. Once under 2V they were discarded, as in "free". I could use them to below 1V with my transistor stuff. Same with depleted D-cells. That would not have worked with Si-transistors (it didn't, I tried later).

One of my "innocent" teenage projects was to copy the idea of a bug from some spy movie. I placed it in a flower pot and then could hear my parents talk upstairs in the living room, on longwave (AFAIK only available on radios in Europe). Just for fun, to see if I could pull that off. Later after heading off to university I confessed.

Didn't the OC71 do 20V Vce?

Yeah, they all leaked like a sieve. But since one could make circuits that ran at less than a volt one only had to convince family and neighborhood to chuck depleted batteries in this here box instead of the garbage can.

Oh, and if you scraped the paint off the glass you could make a nice photo sensor. Try that with contemporary transistors.

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Reply to
Joerg

I have a closet full with paint all over them. ;-)

I only wear a suit for funerals, weddings, and the occasional customer trip. In the last 30 years, the first two happened once or so a year and the latter never. Had a couple customer visits (execs, even) last month, though. Seems many more to come.

;-)

Reply to
krw

I'm with you there. "The last penny got shaved a buck-and-a-half-ago."

I don't but I have never been told to, either.

Touché. The difference is Maxim keeps proving that while things change, management doesn't.

Sure, I wear shorts[*] around the house, with Oxfords. I just can't stand wearing T-shirts or even short-sleeved shirts. Spent a week at the beach in September in swim trunks and oxford shirt. ;-)

[*]Though, with Global Warming, I've already put the shorts up for the Winter.
Reply to
krw

I think I could make a FF toggle at about 100kHz. A bit more if it was clamped to prevent saturation. ft was only a few hundred kHz.

Yup, metal-sleeved or painted glass case filled with grease.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward" 
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Spehro Pefhany

[...]

There was another guy who promised change. Actually hope and change. I never saw the hope part and he made a royal mess.

Yikes. That is something I find odd. However, in places like Singapore people even wear shorts with dress shirts and ties. But short sleeves.

We have stashed the usual record amount of firewood for winter again. I want my fair share of this global warming !

--
Regards, Joerg 

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Reply to
Joerg

Sign up for Obamacare yet? ;-)

I didn't get burned. ;-)

Haven't owned a short-sleeved shirt in at least 45 years (maybe in high school - before I bought my own clothes).

Didn't mean to get you excited. ;-)

Reply to
krw

IIRC the OC71 had 1MHz ft. But the good stuff came soon after: The AF139. That one was usable up to the UHF band, which it was designed for.

Some transistors didn't have grease in them, those were really useful as photo receivers.

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Regards, Joerg 

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Reply to
Joerg

I suspect the hot shower might be one of the most useful design tools known to man.

Reply to
Ralph Barone

A tie is a bizarre anachronism. I'm not sure I even own one any more.

Speaking of bizarre anachronisms, we recently watched the new "Much Ado About Nothing", in modern dress but original Shakespearian dialogue, filmed in b+w in a suburban LA house. Lots of cell phones and neckties. Disconcerting but good.

--
John Larkin                  Highland Technology Inc 
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Reply to
John Larkin

but I do get more current out of the capacitor at the time the switch opens than goes into the circuit

eg:

Version 4 SHEET 1 880 680 WIRE 32 64 -80 64 WIRE 64 64 32 64 WIRE 192 64 160 64 WIRE 256 64 192 64 WIRE 368 64 320 64 WIRE -80 80 -80 64 WIRE 192 96 192 64 WIRE 32 112 32 64 WIRE 368 112 368 64 WIRE 112 144 112 128 WIRE -80 240 -80 160 WIRE 32 240 32 176 WIRE 32 240 -80 240 WIRE 112 240 112 224 WIRE 112 240 32 240 WIRE 192 240 192 176 WIRE 192 240 112 240 WIRE 368 240 368 192 WIRE 368 240 192 240 WIRE -80 256 -80 240 FLAG -80 256 0 SYMBOL ind 208 192 R180 WINDOW 0 -18 84 Left 2 WINDOW 3 -34 24 Left 2 SYMATTR InstName L1 SYMATTR Value 10m SYMBOL cap 16 112 R0 SYMATTR InstName C1 SYMATTR Value 100n SYMBOL diode 256 80 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D1 SYMBOL npn 160 128 M270 WINDOW 0 79 32 Left 2 SYMATTR InstName Q1 SYMBOL current -80 80 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I1 SYMATTR Value 50m SYMBOL current 112 224 R180 WINDOW 0 -25 91 Left 2 WINDOW 3 -274 -46 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I2 SYMATTR Value PULSE(5m 0 0 10n 10n 80u 100u) SYMBOL res 352 96 R0 SYMATTR InstName load SYMATTR Value 50r TEXT -114 290 Left 2 !.tran 2s

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Reply to
Jasen Betts

indeed, ltspice loosk for a steady state. anything above 0ps is too long.

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Reply to
Jasen Betts

When Keithley started using FETs instead of tubes in their electrometers, their most sensitive range went from 100 fA FS to 10 pA FS, and stayed there for years and years. Of course my 405 needs a couple of hours' warm-up before that scale is usable.

BTW there's a Megacycle Meter on eBay for $40 at the moment.

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Cheers

Phil Hobbs

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Phil Hobbs

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