oscillator rectification

[alec_t]

wikipidea has given half wave rectifier Vdc=Vpeak/ pie

Strange. I wonder how that's derived? With good smoothing Vdc ~ Vpk ~ Vrms*√2, whether the rectification is half-wave or full-wave.

 

[ericgibbs]

Strange. I wonder how that's derived? With good smoothing Vdc ~ Vpk ~ Vrms*√2, whether the rectification is half-wave or full-wave.

hi alec,
I have not seen the Wiki link. But I think neptune has not posted the full formula, without smoothing.

https://www.daycounter.com/Calculators/RMS-Calculator.phtml

 

[alec_t]

Hi Eric, I think this is the wiki ref. Something seems iffy.
https://en.wikipedia.org/wiki/Rectifier#Half-wave_rectification

 

[crutschow]

Wikipedia has given half wave rectifier Vdc=Vpeak/ pie
and full wave as Vdc = 2xVpeak/ pie
is there any other formula ?
so if i get same voltage from both half and full then what's the use of using full wave or precision rectifier !

The difference is, I was referring to peak rectification which is used in power supplies to get DC from the AC waveform. For that there is no essential difference since the peak voltage is the same for either half-wave or full-wave rectification.

If, however, you average the signal by running it through a low-pass RC filter then you will get the average Vdc value, which corresponds to the Wikipedia formulas. In that case the average full-wave value is indeed twice the half-wave value.

Since you would likely want to average the oscillator signal as well as the other signal to allow a comparison of DC values, then you are correct in saying that full-wave rectification gives you twice the voltage of half-wave.

So I suggest you use two precision full-wave rectifiers with an averaging RC filter on both outputs for accurate comparison of signal levels.

Edit: But I still don't understand why you are using an oscillator to get a DC level for comparison to the other signal. Just rectify that signal and measure its DC voltage.

 

[carbonzit]

Hi Eric, I think this is the wiki ref. Something seems iffy.
https://en.wikipedia.org/wiki/Rectifier#Half-wave_rectification

Welcome to the world of Wikipedia, the "encyclopedia" that any pimple-faced junior-high-school kid can edit and appear to be an "expert" in.

My policy is to avoid Wikipedia altogether. There are many other (and better) sources of reliable information out there in web-land.

 

[crutschow]

Welcome to the world of Wikipedia, the "encyclopedia" that any pimple-faced junior-high-school kid can edit and appear to be an "expert" in.

My policy is to avoid Wikipedia altogether. There are many other (and better) sources of reliable information out there in web-land.

CZ, I seem to sense, perhaps, a certain dislike for Wikipedia.

Have you actually found incorrect data on that site? (I imagine there is some but I just wondered if you have been personally bitten by bad info from there).

 

[carbonzit]

CZ, I seem to sense, perhaps, a certain dislike for Wikipedia.

Have you actually found incorrect data on that site? (I imagine there is some but I just wondered if you have been personally bitten by bad info from there).

Can't say I have, at least not any out-and-out fabrications, complete falsehoods, anything like that. What I have found is a lot of conjecture, glossing over, emphasizing unimportant issues and missing important ones, unsupported conclusions (sometimes marked by "citation needed" tags, sometimes not), and just plain bad writing.

If you're really interested in exploring the anti-Wikipedia point of view, I suggest looking at Wikipedia Review, a forum much like this one. It's frequented by Wikipedia editors (and even some admins) as well as critics. As with any internet resource, some chaff amidst the wheat, but generally a pretty high S/N ratio.

 

[neptune]

The difference is, I was referring to peak rectification which is used in power supplies to get DC from the AC waveform. For that there is no essential difference since the peak voltage is the same for either half-wave or full-wave rectification.

If, however, you average the signal by running it through a low-pass RC filter then you will get the average Vdc value, which corresponds to the Wikipedia formulas. In that case the average full-wave value is indeed twice the half-wave value.

what is the difference between peak rectification and basic rectification , basic rectification uses diodes ,reistors and cap for smoothing.
how does peak rectification works ?
I think i will use averaging of signals for comaparision to keep the circuit simple

Edit: But I still don't understand why you are using an oscillator to get a DC level for comparison to the other signal. Just rectify that signal and measure its DC voltage.

i will be posting new hread

 

[ericgibbs]

hi neptune,
This is an example of a Peak rectifier [posted to another thread], you can also configure a RMS and Average circuit

 

[neptune]

can peak wave rectification be achieved by Diode full wave rectification ?

 

[ericgibbs]

can peak wave rectification be achieved by Diode full wave rectification ?

Yes, but not less than or close to the forward diode voltage drops, not less than ~ 1 to 2V.

 

[neptune]

can you show me how in LT spice

 

[ericgibbs]

can you show me how in LT spice

Do you mean a diode bridge.?

Please post of what you think the circuit would look like, I can get an idea what you mean.


EDIT:
Look at this pdf

 

[neptune]

Now this is normal rectifier(half wave) with averaging output.
how should i design peak to peak in LT spice. doesnt matter if its using 2 or 4 diode

 

[ericgibbs]

Now this is normal rectifier(half wave) with averaging output.
how should i design peak to peak in LT spice. doesnt matter if its using 2 or 4 diode

The circuit in Post #29, will do exactly what you are asking, why dont you build it and run it.???

 

[neptune]

ya i will build it. i am on my way. but as for extra knowledge and curosity i was asking this