For the beginners ? here a bit of electronics theory

He jumps to "in conclusion" too soon. There's capacitances to worry about, and inductor saturation.

I like to use a dual-winding inductor, like the DRQ series, and build an autotransformer boost converter, which helps get high output voltage.

On a sunny day (Sun, 09 Oct 2022 03:12:53 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

The old CRT TV flyback was very interesting

64 uS line time, few uS flyback time, 25 kV HV tuned, linear current in deflection coil... S correction.. plus some pincussion corrections for color TV. Later ones had a voltage multiplier. Early ones a PD100 stabilizer triode on the 25 kV. I have kept one CRT color monitor in the attic, my personal particle accelerator!

My first CRT scope used a BW 43 cm CRT and an old car ignition coil driven by an audio amplifier at a few kHz for HV and deflection. Not very linear but great fun, Tube diode as HV rectifier.

For real HV:

I have one, 20kV is more what it looks like

PMT HV supply:

Or this PMT circuit, some kV:

Here's a small HV supply:

LTC3803 is a great little chip.

I'm currently designing the power supplies for a new delay generator box. Input is from a +12 or +24 wart, either has to work. The design engineer C wants +20Q, +5Q, +4Q, +3.3, +1.8, +1.35, +1, -6, and -5Q, where Q means a very quiet supply. The C wants +2.5 too and she won't get it; enough is enough.

It has to all fit into 4 square inches x 0.2 high and use parts we can get and not splatter a bunch of EMI. Yuk. It's like playing a

9-dimensional chess game when you're drunk.

Zynq FPGAs are great but real power hogs.

On a sunny day (Sun, 09 Oct 2022 08:45:26 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

Interesting, that switch S2 to lower the voltage Also that LED in series with the 78L15 to get to 17 V, I have used LEDs as zeners several times. Never used that LTC3803, usually program a PIC 18F14K22 as those have a comparator that is hardwired to its PWM generator so overcurrent trigger works very good and fast, plus ADCs of course, and serial and i2c communication.

Ground loops... ? looks a bit .. well.. much.. some LM317s ?? LOL one switcher with transformer with separate secondary windings for + and - and LM317s to the little voltage steps.. Realy need to know the currents.. and stabilization accuracy.

So no LM317 but those LM2576 switchers? I once did a thyristor regulator followed by a transistor regulator to filter the ripple the tranistor regulator drove the thyristor so there would always be just enough voltage across the series transistor to filter the ripple..

The 3803 runs the inductor to a peak current every cycle, which is cool. It results in a constant-power limit much above Vin, rather than constant-current.

We need low dropout linears to save power. LM1117 or preferably LM2941, whatever we can get.

Total maybe 8 watts. The horrble Zynq may need an amp or more of +1 alone.

Looks like we can get the cute little TPS5 series of synchronous switchers. We just scored a reel of TPS562208 for 19 cents each, but they are 17v max input so we need another part for the first switcher.

I like LM2576, dumb and quiet, but it's big and needs a big catch diode and a giant inductor. Need something else.

I can top that. A pre-regulator in the AC line, a giant power resistor and a shunt thysistor, bang-bang on/off regulation.

On a sunny day (Sun, 09 Oct 2022 12:37:01 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

Shunt thyristor.. sounds like a crowbar, resistor equals heat dissipation...

Not a crowbar. The thyristor shorted the series resistor when the voltage to a big amp was low. That softened the powerup surge too.

This idea fatigued to death a bunch of big metal-case military-style

250 watt wirewound resistors. These types worked:

Thick film on porcelain steel. Very tough.

On a sunny day (Mon, 10 Oct 2022 08:01:04 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

Ah, got it now

I am still using these:

little bit of heatsink.

And have this:

things are getting ever smaller, in a big country like the US one would think 'space enough' but no, or do they expect it to fall apart to such a small size ;-) In the old days, NTC resistors in the first Philips color TV sets, K6 circuit diagram: see top left for many, one looked like a big black piece of coal. One in series with the heaters, one in series with the DC power, one in series with the degaussing coils...

Evolution from tubes to transistors in their color TVs:

Brings back memories... things / circuits have gotten so much simpler with everything in chips but the knowledge for how it really works is worth gold, to be able to do it even with normal components, as we now see with the chip shortage. I have the distinct impression current civilization is sort of stuck

or moving backward, I see things here done bad that would not have happened that way in the seventies... carelessness or incompetence... you are lucky if you have competent people working for you, hard to find any here these days it seems.

My regulation scheme destroyed that style of resistor. After some months they would short to the case.

I blame Microsoft.

On a sunny day (Mon, 10 Oct 2022 09:30:09 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

Oh, I dunno... sure MS windblows is made for profit only... bloated at that, open source is nice, Linux is getting more bloated too, RatHead did its best to make it proprietary by creating incompatibilities and some of that unfortunately make it into the kernel (dbus comes to mind)... But on a wider scale than software...: When the Roman empire collapsed and was concurred by barbarians much of their knowledge and science was lost Took centuries to get some rebirth in Europe Now we are ruled by green idiots who oppose our survival it seems I knew some, one even did not want into the car because it made CO2 and polluted the world... and that was already in the seventies!! Now it is much worse... All shit science, wars coming, US Military Industrial Complex creates those, only skyscrapers will be left just like the Aztec pyramids Jippee!!!!

The article this is from calls this dual-winding inductor boost topology "novel" but I find it hard to believe it's that novel:

I hardly think that an autotransformer boost converter is a recent invention. B+W tube TVs usually did that.

The old points-and-coil car ignition was similar.

On a sunny day (Tue, 11 Oct 2022 12:44:07 -0400) it happened bitrex snipped-for-privacy@example.net wrote in <r3h1L.115010$ snipped-for-privacy@fx36.iad:

Just the secundary power in series, nothing new, But why LK2? Not really needed.. same for LK1 if it is not coupled to anything, or is that the 'new' part?

They probably represent the leakage inductances in a simulation.

The way you represent "leakage inductance" in an LTSpice simulation of a pair of coupled inductors is by picking the right coupling factor k in the

string L1 L2 K, where K can vary from almost one (for very tightly coupled coils) to something very close to zero for very loosely coupled coils.

You don't add an extra inductor.

On a sunny day (Tue, 11 Oct 2022 22:05:11 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

Would here be a market for that: 'leakage inductors' ? ;-) I mean targeting simulations using designers.... "do not forget the leakage inductors!" sort of commercial.. hehe

World upside down...

Except when it makes sense to explicitly add the leakage for simulation. A recent example I had was a three winding transformer where two windings are bifilar very closely coupled but the third winding is loosely coupled (because of HV clearances).

piglet

piglet snipped-for-privacy@hotmail.com wrote in news:ti5uj9$1dsan$ snipped-for-privacy@dont-email.me:

"coupling" is via the core. Volts per turn does not change because you spaced the HV winding out a bit.

You should be able to manage that with three strings

L1 L2 0.99 plus L1 L3 0.8 and L2 L3 0.8

We had a thread about something like this a month or so ago, and somebody tried that and it seemed to work.