Savii

modified 10 years ago

PWM modulation and demodulation

218

02:36:29

In this circuit a wave of 10kHz will modulated in PWM with a carrie signal of 320kHz.
At the output of the comparator, two RC low-pass filters (with f=10kHz) will reconstruct the modulant signal.

published 10 years ago

Karsten

10 years ago

That is PWM, not FM. In FM, the frequency is being changed while the duty cycle stays the same. In PWM, the duty cycle is being changed while the frequency stays the same. And guess what, you're changing the duty cycle.

Karsten

10 years ago

Although that PWM signal is beautiful.

Savii

10 years ago

You are right.. We have a rectangular signal at the output.. It's a PWM

Savii

10 years ago

I change the name of the circuit

hurz

10 years ago

Check this, fastest and high precision decimation filter passive http://everycircuit.com/circuit/6000713779904512

Karsten

10 years ago

"It's a PWM" sounds funny. Imagine getting a transmission from a rocket saying: "Houston, we have a problem. It's a PWM"

hurz

10 years ago

Dont go in space bulgaria is much closer ;-)

Savii

10 years ago

Karsten znaci ti si b'lgarin?

Karsten

10 years ago

Well... actually if you take the distance between here and Bulgaria (about 1500 km according to Google Maps) and the definition of the beginning of space from the FAI (100km NN) then space is closer than Bulgaria

Karsten

10 years ago

Savii I don't understand your question, but if you asked if I'm from Bulgaria then no I'm from Germany.

Savii

10 years ago

I didn't understand the expression of hurz.. sorry

hurz

10 years ago

How much effort it takes to get in space? Doesn't matter were you living. Today i measured 230.5V

hurz

10 years ago

Now its 230.4V shit

thebugger

10 years ago

I'm from Bulgaria and i don't get the reference hahah

thebugger

10 years ago

By the way, every type of modulation (except FM) can be demodulated in the same way. AM,PAM,PWM can all be demodulated with an envelope detector.

hurz

10 years ago

Now its 229.9V

azizablak

10 years ago

Kkkkkkkk

thebugger

10 years ago

What are you measuring? The mains? It's bound to vary to some point. I think it was 5% tolerance

thebugger

10 years ago

In urban regions it's very stable, rarely reaching 5% tolerance. In rural areas it varies more, more commonly dropping, instead of rising.

hurz

10 years ago

232.3V (sunny weather) but more important is the frequency it is reverse proportional to the load.

Savii

10 years ago

Do you know that in areas near to Rome they have 130V in the monophase.. And they must use the threephase system to reach 220V (130*V3)

thebugger

10 years ago

In America the mains is 120V/60Hz too.

hurz

10 years ago

@savii, 130V in two phases is 225V, not to bad to power rated devices for 230V.

Savii

10 years ago

The problem is that in Italy the main is 230V 50Hz

thebugger

10 years ago

Not a problem. You can always step up or step down the voltage to suit your needs with a transformer. I have a 220V to 110V tranaformer in home, which i used to use for powering vacuum tubes with a voltage doubler, because i didn't have an isolation transformer

Savii

10 years ago

Yes I know.. I sayid only that it isn't practical.. You should have a big transformer with minimal 4kVA (for appartments), and when we see for industrial application in which We have necessity of 400V threephase with big power We need a 130-400V transformers (who are not usual in Europe) with many kVA

thebugger

10 years ago

Yes, that's why transformers are made for specific appliances. My 230V-120V transformer is indeed rather large, but it was designed for an old refrigerator we used to have. No more than 200W. I think it's better to have 230V and not need it completely, than to have 120V and need more. But transformers are inevitable. In rural areas, I often see these huge monstrous transformers, that step down voltages of over 10kV to the household 230V. I'd like to see one blow up hahahah

Karsten

10 years ago

Now I'm kinda curious to see one explode too.

thebugger

10 years ago

Haha, right? It should be spectacular, watching 15kV melt the iron core of the transformer :D

Savii

10 years ago

Better no... :S

JeffreyH

10 years ago

Are the transformers delta or wye?

thebugger

10 years ago

I'm not really sure. High voltage high power distribution is not my major. I think it's delta. Surely it's three phase. I've seen the 3 input leads.

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