Inductor current can't be suddenly cutoff if no freewheel diode is attached

NOT true! Look a ten million or so car ignition systems since the late 1800's.

Depends on your definition of "suddenly" >:-} ...Jim Thompson

Seems we now have an inordinate number of imbeciles issuing "tutorials" on subjects for which they have no clue.

A product of the "education" system and googlegroups?

I blanket killfile googlegroups and gmail posters, making it trivial to whitelist the remaining handful of intelligent beings that post from there. ...Jim Thompson

Or indeed, on your definition of cut off.

Sylvia.

Oh, please! Oh, please! Don't cut it off >:-} ...Jim Thompson

Or even your definition of "inductor current".

Best regards, Spehro Pefhany

It's hard to build a practical boost converter with over 20:1 or so step-up ratio. At some point, the flyback swing charges up all the circuit capacitance, mosfet and winding capacitance, and you can't get any higher. Magnetic losses don't help, either.

And you can buy avalanche-rated mosfets and bipolars.

et-

up

As has been said, car ignition systems do better than 20:1.

The transformers are wound for low inter-winding capacitance. Mimimun is su pposed to be single-layer winding with the wires spaced by about their own diameter, but it's hard to get much inductance that way, unless you build s omething quite big - as Nickola Tesla did - but "banked" windings do help.

ched. New tutorial is ready

d_freewheel_diode.php

The reason the OP posted it was to get people to check the link out. His (o r hers) banner commercials then earned 10cents per click

Want to earn relatively easy money? - copy very popular websites on the net , and add banner commercials. Make sure to register keywords to Google.com

Sit back and watch the flow of money (granted this was easier 5-10 years ag o)

Skål

Klaus

I should imagine that most people here use ad- and popup-blockers.

Sort of makes it a bit pointless, his posting here. I had to look at my blocked items window to see the google syndication script hiding there.

As to those who don't block gratuitous ads, they have only themselves to blame.

This CD-type (IRL) makes 300V from +4V...

Will there be a song now "Do the Bobbit?

Twitter!!

It's interesting that, whenever a woman posts here, there are guys, presumably either horny teenagers or senile old gits, who start up snarky sexual innuendo. They're not even very good at it.

See the same thing in s.e.b.

Designed any "cute" circuits lately ?:-) ...Jim Thompson

The big board is the test fixture. The little board (I think 0.75x2" qualifies as "cute") is a 150+ amp, 4ish kilowatt precision laser driver, with onboard boost-doubler converter. The one that you didn't like.

The Brat did beautiful PCB layouts on these. They both worked first time. The customer connected +10 to the 5 volt supply and blew up the first one that we shipped, but these things happen.

Currently I'm working on an active magnetic field shield, an aircraft engine transducer simulator, some thermal stuff for an EUV photodiode digitizer, and some optical stuff having to do with semiconductor fab. And still tweaking my shrimp-and-grits and bread pudding recipes.

How about you? Still working?

Yep. Still cranking out custom chips.

Will you show us the final schematic of the boost-doubler? As originally posted it _did_ have problems. ...Jim Thompson

What problems?

This is essentially the same as the "bubbler" circuit I posted previously. Here's the (censored) schematic of the real thing:

It's tiny and it works great. It's simple, efficient, and very tunable. The current pulled from the customer's supply, during chargeup or recharge, is nearly flat and is easily settable.