zorgrian

modified 7 years ago

New Simple Low Pass Filter

265

04:03:22

⭐️Simple RC filter that fails to completely remove DC component (for totally known and obvious reasons)⭐️

TRY RUNNING WITHOUT THE BODE PLOT

This RC filter has a corner frequency of 159.15494 kHz. As with all such designs, the calculated corner frequency is not the effective start point of attention. Indeed this is probably nearer 50 kHz. 

⭐️Happy Simple Circuits⭐️

73

Enjoy!

published 7 years ago

BillyT

7 years ago

When the resistor and capacitor are swapped,the DC is seen to be removed, so it depends what and where you are looking at.

hurz

7 years ago

@zorgrian, infaltion of “simple“ followed by “wooops“ i forgot to swap some components 😁 Zorg 👍

kiani

7 years ago

It is a colanderum.

hurz

7 years ago

I have a simple idea, i think we need a simple filter which allows EC users to use the word “simple“ only ones a day! So simple is that.

ViolationMad

7 years ago

The concept of „simple“ is not just for simplicisimus himself. I don’t see any problem of something being easier as long as it’s still useful.

zorgrian

7 years ago

Its so Simple as @hurz points out (that's my once today)

hurz

7 years ago

@viola, “simple“ is not equal “easy“ i think kiani said that but removed it

kiani

7 years ago

@Hurz am glad you read 📖 it before i removed it. Yes most we often think with our eyes. " i" say a single hyrogen atom with single proton and single electron contains all the complications of the universe, a complicated universe, we might create, but a simple single hyrogen atom, who can create?!

kiani

7 years ago

About the phsyciastic circuit, i think @zorgrian you have two capacitors in the circuit, one that can discharge and one the can not. But i have been known to've been wrong quite often in the past.

zorgrian

7 years ago

The RC low pass design here, does not have a DC path to ground. If we swap the resistor and capacitor around, then we do have a DC path to ground. However, in so doing, the result is a high pass filter ∆

kiani

7 years ago

But how can it remove the dc afterwards, if we want to stop the flow of water 💦 shouln' t we block it before the tap and not after. In fact it has blocked the Dc from flooding the earth.

kiani

7 years ago

Or mabe i am missing the point as usual.

eekee

7 years ago

i'm not sure there is a point. :) if there is, put a 5uf cap between the 20v & 1kr, then a 10kr from ground to the join of 5uf/1k. 'problem' solved. or you could probably put these two on the output of the filter instead.

zorgrian

7 years ago

You can easily place a resistive load after the capacitor. However, if this resistance is not high it will dramatically change the filter characteristics.

zorgrian

7 years ago

Check this out http://everycircuit.com/circuit/6297956826480640

zorgrian

7 years ago

This is another approach. There's a capacitor in series and this is followed by a 10K ohm load, which removes all DC offset. You end up with a sign wave that's centred about zero volts.

kiani

7 years ago

Should' t we expect a low pass filter allow the lowest frequency which is dc?! And that is what is doing. The modifid cct. Is no longer a lowpass but a bandpass. ( according to v/i curve)'. It is good that lowpass does not block dc, as it is used in smps, s.

zorgrian

7 years ago

Um .... Of course if you place a series capacitor before a load, you end up with a band pass.

zorgrian

7 years ago

The first example does not block DC. No! But you were on about 'stopping the flow' and this looked like you wanted to block the DC component.

kiani

7 years ago

159.,,,,, khz is when the o/p drops by 3db. Then there is a rate of attenuation, ( which is not sharp, cause"rc" time constsnt). so if we want a low pass with dc removed, is already not lowpass and is kind of bandpass,. 0Hz is very much low grequency, do we want it rrmoved?! = bsndpsss......wewant it not removed?! = lowpass. We can` t have our cake and eat it. A lowpass that allows dc is officially a bandpass, isn' t it?!

zorgrian

7 years ago

Ok so you design one now then?

zorgrian

7 years ago

(for totally known and obvious reasons)⭐️

zorgrian

7 years ago

2 days ago, I warned that this circuit fails to remove a DC offset. I also stated that the calculated corner frequency is higher than the real value. This is what happens.... And this is the ideal EC world. In reality its worse

kiani

7 years ago

What shall i design,, a low pass filter that isn' t?! .. {A battery is also a capacitor. So the cct. Is blocking dc. It is blocking it st the source ( the other side) stopping it to discharge into the ground. }. The thing is this is not really a low pass filter ( we call it that, just a name) . If the world was perfect, it wouldn' t be here at all. After all isn' t what science is about?! We use the improfections to our advantage, and make things with it that are imperfect?!

LeButch

7 years ago

Do you start posting your circuits with stars now? Like Lenz?

kiani

7 years ago

@lebutch i took up boxing ( as sport) not csuse i wanted to punch 👊 people, but cause wanted to let my aggressions out, so i don' t have to punch people. Do you do any sports?!

kiani

7 years ago

@zorgrian btw. I want to get an app that dies maths notations, don' t know which id safe ine cause they apparantly can read everyting you type on keyboard including bank acount number, etc and send them to ehom ever, which one do you use,. Would you send us info. Plz.

kiani

7 years ago

@zorgrian here is my attempt, . Don' t if it is any good. http://everycircuit.com/circuit/5430303102599168

zorgrian

7 years ago

Yes that works but its not an RC filter

zorgrian

7 years ago

You mean an android or iPhone app? These operating systems are all potential spyware

kiani

7 years ago

It is an Android phone. There are 2 or 3 on googleplay, but with all get a warnning that they are able to copy and read your phone book, and passwords to your email,,,, just about every button you press on the keyboard.

kiani

7 years ago

Just noticed an interesting point in your circuit,,,,,the RC filter starts to attenuate at 50Khz, ( as you mentioned) . The Fc of filter { 159.15494), time onterval, is a fraction of 50khz. Related...?!

kiani

7 years ago

{1/(159.15494*10^3)}/2 =pi

kiani

7 years ago

((50*10^3)^-1 * pi) / 2 = pi

2ctiby

7 years ago

@kiani... both of these maths queries are wrong... probably best not to pursue that line.

kiani

7 years ago

i guess if one looks hard enough, they always find pi.

kiani

7 years ago

@2ctiby yes sorry, it is completely wrong, overlooked the obvious.. This 159.15494 Khz... Is actuallu. 1/2pi.

2ctiby

7 years ago

@kiani ... yes 1/(2pi). On a side issue relevant to your other work... you may want to consider that sin(x)/× when integrated with respect to x between zero and infinity ... will give you (1/2)pi ... which may be a lot easier to work with than all of the ln etc. ... but I don't know if op-amps will handle that sort of integration... they have issues and tend to be better as lpf... I have no experience down that avenue.

hadrianhu

7 years ago

How did you make the Bode plot? I want to do it on my circuits as well

kiani

7 years ago

There are two plot mechsnism on EC. One which lrts uou plot v againsy v a or i. If you press the button with eye. It displays v or i, now therer is a sideay arrow on it, if you touch it again the arrow will point upwards, which means thst has become your base now as oposed to time. The second is the frequency response plot, this you can only do if you have an ac source, ( it doedn't work with square). There are two play ▶ buttons if you choose the second one it goes to boad plt mode. And plots gain against frequency. Hope this helps.

kiani

7 years ago

@Hadrianhu well.. Did this help?!

eekee

7 years ago

A low pass filter + a high pass filter is not really the same as a bandpass filter. Bandpass fiters don't usually have a flat pass-band, it's more of a hump.

hadrianhu

7 years ago

This helps a lot. Thanks

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