Very high gain transformerless boost converter - is it possible

ution :-)

nk

at Phil

I've got it. Charge each doorknob to 30kV then fire it into the top of the plastic tube with a toy cannon. Rotating contacts top & bottom extract the output from the pile of Cs, while they're let out at the bottom at the same rate as they're fired into the top.

NT

Were CVs (continuously variable ratio gears) not available then? I assume the reason to not use them was slow controller response loop.

NT

Huh, I have no idea, but I'd bet (a beverage) it's better than 1%.

George H. I took data at an FEL that used a big ass Van de Graff to accelerate the electrons.

There are mechanical generators that do that by putting HV axial caps on what's basically a bandolier. Similar to a van de Graaf but with a lot more stooch.

Cheers

Phil Hobbs

I still feel sorry for mechanical engineers who have no decent equivalent to a switching regulator.

It's called a gearbox. Not suitable for gramophone speed regulation, but belt drive turntables offer other approaches (not that any of them would be a sensible choice in real life).

the plastic tube with a toy cannon. Rotating contacts top & bottom extract the output from the pile of Cs, while they're let out at the bottom at the same rate as they're fired into the top.

Oh, not seen those.

NT

If I were really going to place a bet I'd take you on. I daresay there's a fair difference between the latest higher-tech van de graaf and something from their heyday.

NT

There is the hit & miss engine. Not quite the same frequency response though. I guess it's more equivalent to the Philips G8 style triac & dropper PSU that either let a whole half-cycle through or didn't.

NT

Nothing so fancy. I figured that I could just charge them and drop them into the tube. When the tube is full, it could be ballpark a megavolt between the ends.

That'd be a transformer.

CVT is the best they've got, but it's a variac, and like a variac, suffers from losses where the brushes short across turns, and wear.

Here's a project that tried:

It's a shame that no material has an extremely high speed of sound. Beryllium is the highest by far among metals, topped only by diamond (maybe). That's not very encouraging for an application that's expecting high impact and abrasion forces...

I would suspect a hydraulically actuated resonant converter might not be too terrible, but it would be a pain to design, even worse of a pain to dampen properly (to keep it from shaking the car apart, let alone be quiet enough for the passengers), on account of the many more vibrational degrees of freedom mechanical parts have, compared to electrical circuits; and it still wouldn't get anywhere near the power density of an electric converter of the same rating.

Tim

tabbypurr wrote

Ferry Zimple

We call that a 'variomatic', wheels with varying diameter, also seen in dome desktop electric drills, first here used in the DAF automobile transmission:

The centrifugal governor controls the CVT and thus the speed of the generator, while the electric motor is running at approx. the same speed. The load on the motor changes and is reduced for a lower transmission ratio, and so does the power consumption.

jurb6006 wrote

It had an electric motor though, and a lever that moved the pushing plate fricton plate if you want) from the governer, so you could also move it to 45 rpm Made by Philips. IIRC it had worm drive from the motor to the turntable... Cannot find a picture of it online. Had great fun with it, learned a lot from it.

build a constant-speed flywheel

that's going to require some tricky levers, but the right force to distance curve should allow you to construct a flywheel with masses that move radially that has near constant speed over a range of angular momentums.

this could perhaps be could be a horizontal flywheel that has steel balls balls thay roll up inclined tracks by "centrifugal force"

Then sense the position of the masses (perhaps use magnets) and have that turn the (spring) motor on and off.

Well, not one that fits in the palm of the hand, but automatic transmissions are not unknown. I've got a couple of 'em parked outside.

The modern equivalent (pelletron) claims circa 100 uA and 25MV capability: that's about four horsepower, and I'd guess the friction losses in the link-chain are very low indeed. The whole system is basically a motor, cogwheel, chain, and idler wheel at HV.

The variomatic was a rather interesting concept. The DAFs could really have done with computer control, vacuum control was far from ideal. And the cars so needed a restyle!

NT

Lasse Langwadt Christensen wrote in news:c0d2cac5- snipped-for-privacy@googlegroups.com:

Thanks. Nice, descriptive article(s).

Right, (I figure I owe most people here a six pack of 'beverages' already so another hardly matters.) But I was thinking of a lower cost 'toy' Van der Graff, like is used in physics demo's. I could ask some of the physics 'lab guys' to try and measure one. Heck, someone might have already done it.

George H.