Passive RC high pass filter tutorial! 

Dude always. Lol

When I graduated from college there will be RU-vid logo and tittle on my degree instead of my collage name :D :D

Too true.

That moment when you turn random buttons to get desired output on CRO and when you get it , you have no idea which button you turned to get it . 😂😂

Ironically, most of my college learning came from RU-vid - however, one should realise that good research techniques are required when doing so. There's so much nonsense floating about, a good researcher must have the ability to distinguish the accurate and useful information from all the click bait, hype and other nonsense.

I respect your sacrifice in Ravenholm my friend

@@KayBeeOG A shepherd must tend to his flock. Especially when they have grown unruly.

You are welcome. Btw chances are you have some sort of ground loop and want a ground loop filter. Or a 50/60Hz notch filter.

Thank you. The project is battery powered and the humming is in the region of 250Hz which is very noticeable. At first I was using just a 100nF DC blocking capacitor in series with the audio signal line but every time the radio transmits, it would wipe out the audio signal completely - unless I went near the antenna or touched the metal box the project is housed in and then the audio would appear. I got round this by replacing the 100nF DC blocking cap with a 22uF electrolytic which seemed to cure the problem of the RF completely wiping out the audio or me having any effect on it when I go near it - however it has brought that nasty hum with it. I've just been playing with a circuit simulator where I've mocked up an active high pass filter with Op Amp but if I use an electrolytic capacitor for my filter, it complains about reverse voltage so I'm guessing they're not suited for the job. My concern is, if I add the low pass filter with a ceramic capacitor that I'll be back to square one with the RF killing the audio so they'll be no hum to filter out lol.... I am beginning to suspect that it is as you say, a ground loop going on. In which case, it may mean a re-design of my PCB to use some sort of star grounding? Guess I'm just going to have to prototype it up, suck it and see, as they say. :)

Yeah me too

Yeah, if someone figured that out, please do comment. The sentence makes no sense.

It will instantaneously appear on the other side because there will be close to zero voltage drop across the capacitor at high frequencies. It will pass straight throught. It's the voltage drop across the capacitor that cannot change instantanously. And it's the voltage drop across the capacitor that cancel out signal waves at low frequencies.

So - correct me if I am wrong - the capacitor can act as a "variable resistor" depending on the frequency, whereby its "resistance" (capacitive reactance) decreases as the frequency increases. There's an inverse relationship there. The arrangement as shown in the video is very similar to that of a voltage divider, so the filter can be thought of in those terms. If, for a highpass filter, the capacitor is R1 and other - actual - resistor is R2, then with low frequencies, R1 should be relatively large compared to R2, so that there is a significant voltage drop across R1, so less of the signal makes it across R2. On the other hand, if the frequency is high, R1 should drop, attaining a value way less than R2. In that case, there is more of the signal to be dropped across R2, the actual resistor in this case. So the higher frequencies pass with less attenuation. (Remember that the voltage dropped across a resistor is proportional to the resistance value, as Ohm's law describes.) Certainly, a real-life circuit is not perfect, but hopefully the above provides some intuition. I found it helpful to draw out voltage divider circuits on paper and play around with different case scenarios.

Jason W. Yes. Your word for the day is Impedance.

mike samaki I think that was a function generator, not an oscilloscope

Me too got confused at the same part! Have you got the reason for the same yet!!

This may be a late reply, but in my understanding the high value resistor serves as a current limiter. The microphone may not be designed to handle very high current values. More information here : en.wikipedia.org/wiki/Current_limiting

I think it’s the other way. The voltage at the + and - nodes of the op amp will be the same. Since the gain is Vout/Vin, and we know that the gain is 10, the output will be 90V theoretically. Practically, it’s just maxed at 9V. By adding the resistor, it reduces the voltage at the + node, which reduces the voltage at the - node. I suppose we could just lower the microphone voltage, but you would need two power supplies, which is inconvenient. So yes, the frequency cutoff would be the correct value, but the resistor value would not divide the voltage enough so the output wouldn’t distort.

I think the gain in this case is 100,

be cause the sound is an Ac signal , we just need Ac , so we filter Dc , and if we diden't filter dc we will have noise on the specker's, plus it can domage the specker's cause the dc is emplified with the opam's and can be 10's of Volt (this equal's domaged specker's ) and if we see the ac in the input it was just 0.002v and after omplification can be 1v or 2

+bilal h that makes sense. Thank you

you welcome

and if you said so why we have the dc from the first position. then we filter it ?!!, the answer is this type of microphone needs dc voltage to work , then from it's result (generate Ac sound waves + dc offset) we filter dc , there is a microphones called dynamic microphones very used don't need dc so there is no need on it to have high pass filter or dc voltage this type of microphones are directly attached to the opamp.

Your channel is gold

i have the same question :P

@@distortedmist Signal Generator provides the 20 mV sine wave and the DC voltage provides the necessary offset.

An active filter has an active component such as an Op-amp in it while a passive one only has passive components

well I will watch even the High pass LC filters

+Personal voice signal

Please answer mee

It works because a cap blocks dc.

dean smith Same for me :/