Volts, amps and electric power supplies/components

[Tim Watts]

I really have no idea what you are on about...

[tabbypurr]

no, not arranged as a doubler. Go rename yourself Rodney. Or are you him?

NT

[Cursitor Doom]

I see. So you're allying yourself with "ed" who asserts that rectified mains voltage in the UK is 650V, then?

[tabbypurr]

If you don't know that uk mains 230/240v ac can be rectified to either 320 or 640 there really is no sense in any further discussion

[Julian Barnes]

Don't waste any more time on this tabbytroll and his ravings, CD. He's pulling everybody's pisser.

[Johnny B Good]

Strictly speaking, CD is correct. Ed's minor error re item 4 was the reference to a bridge rectifier instead of a voltage doubling two diode two capacitor circuit (which can also be made up using a bridge rectifier of adequate PIV rating and two smoothing capacitors).

Incidentally, unless the situation regarding the uptake of PFC upgrades to SMPSUs has vastly improved in recent years, the conversion coefficient to translate rms voltage to peak voltage approximates closer to 1.4 than it does to the the more accurate 1.414 value.

The last time I had occasion to sample the mains supply waveform, some 4 or 5 years ago, I did notice it was a little flat topped compared to a true sinewave. I presumed it was all that loading from smpsu powered kit not incorporating any PFC circuitry to spread the HT rectifier packs' conduction angle further away from the waveform crest (the 'flat top' had a slight upward slope).

[Johnny B Good]

====snip====

One is almost tempted to say that the "Society of Electronic and Radio Technicians" is now a "Dead SERT". :-)

Sorry, I'll get my coat now.

[TomSawer]

It SERTainly is!

[TomSawer]

Explain how you would obtain 650v directly from a 230v rms supply.

[Cursitor Doom]

I wouldn't hold your breath waiting for an answer. Seems some folk here don't know the very considerable (x2) difference between peak voltage and peak-to-peak voltage. I suspect that's the root of their comprehension problem, anyway.

[tabbypurr]

For the benefit of electronics newbies, D1 goes from L to C1, providing +320v D2 goes from L to C2, providing -320v. The potential difference on the output is thus 640v. For the benefit of pedants, no voltage doubling has occurred, it's just sample & hold of the 230/240v ac waveform.

NT

[The Natural Philosopher]

depends on how you rectify it.

[Fredxxx]

It may not be a voltage doubler in your eyes, but a number of text books quite happily describe this circuit as a voltage doubler.

[John Rumm]

Ed's description was fine - the pedants might argue at the use of the word "bridge" while describing the half wave rectification, but it ought to be clear what was intended:

D1

---------+----->|--------+----------- +V peak | | | | | | +

230 | --- C1 VAC | --- | | | | | | ------------------------+ | | | | + | --- C2 | --- | | | D2 | -----|

[Cursitor Doom]

I keep probably a dozen standard works on power supply design. I've dug out 'Switchmode Power Supply Handbook' by Keith Billings, which is the premier authority on the subject. The relevant section is sect. 6.2 on page 1.55: "Typical dual-voltage capacitor input filter circuit" which is described several times as a VOLTAGE DOUBLER. As I stated about 20 posts ago. If tabbypurr is such an expert as he professes to be, I assume he'll have this handbook or something similar to educate himself with. Ignorance is one thing, rudeness AND ignorance that takes up my valuable time just makes me angry. GGGGRRRR!!!

[tabbypurr]

that some describe it as a doubler doesn't mean it does. Same as constant current more often means current limit. It ain't too hard to see that what it does is just sample & hold.

NT

[whisky-dave]

How ? Can you also rectifiy it to a tin of hot tomoto soup,? I'd believe that more

[TomSawer]

Surley the circuit is only two half wave rectifiers - one using the negative peak and the positive peak. It is only " doubling" the voltage because the output is taken across the two capacitors rather than from the common "neutral" rail. It wouldn't normally be called sample and hold.

[The Natural Philosopher]

the problem is that there is no defined 'standard' for what most electronics is 'called'

[TomSawer]

Agreed. But the name/terminology used implies a certain mode of operation.