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Explain this small circuit please....

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blue6x

New Member
I just want to know how this circuit works...

Thanks for your replies...
 

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blue6x

New Member
can you please elaborate on the function of that LC filter.
the signal input of the op-amp came from a sweep generator similar to this one.
i just wonder about the frequency sent by this anf the frequency filtered out by the LC filter.
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
Not without a lot of examination and calculations - and presumably this is related to your already deleted thread - so isn't suitable for discussion here!.
 

blue6x

New Member
can i just ask one more question, why they this is illegal, yet the market still offers this device. thanks a lot for you replies.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
blue6x said:
can i just ask one more question, why they this is illegal, yet the market still offers this device. thanks a lot for you replies.

Selling such devices isn't illegal in most countries, but USING them is, there's no acceptable reason to have such a device, and they are quite rightly illegal.
 

HarveyH42

Banned
Is this a 'Guess the Illegal mystery device' thread? I think I got a good idea, but will keep it to myself this time. That topic is to well used, and we just went through all that...
 

blue6x

New Member
ell, i would be asking your insights on the above circuit, if you would like to answer.

I am more particulrly interested on what an lc filter does....

Thanks
 

HarveyH42

Banned
L is the inductor, C is the capacitor. Filters are used to remove unwanted components of a signal. Didn't really study the circuit to guess which type, mostly tried to figure out why its illegal to use it.
 

zachtheterrible

Active Member
Very simply an LC filter lets certain frequencies pass and attenuates others. I believe that this is a bandpass filter, meaning that it attenuates frequencies higher and lower than the passing frequency. I'm not sure though.

A lowpass filter attenuates high frequencies and passes lower ones.

A highpass filter attenuates low frequencies and passes higher ones.

Research google for more info!
 

Nigel Goodwin

Super Moderator
Most Helpful Member
HarveyH42 said:
L is the inductor, C is the capacitor. Filters are used to remove unwanted components of a signal. Didn't really study the circuit to guess which type, mostly tried to figure out why its illegal to use it.

Cell phone jammer.
 

blue6x

New Member
thanks a lot, it could be really a bandpass filter..... based on its application..
nigel, thanks for the info.... i appreciate your help... also to other guys here....
 

Hero999

Banned
blue6x said:
I just want to know how this circuit works...
It doesn't, the LM741 won't work at these high frequencies.
 

Papabravo

Well-Known Member
Hero999 said:
It doesn't, the LM741 won't work at these high frequencies.
No opamp will work at those frequencies. If someone says otherwise then they are most probably fibbing for the purpose of separating some hard earned cash from your wallet.
 

Hero999

Banned
An LM741 working @80MHz? Don't be silly!
 

joecool85

Member
Out of curiosity, why would anyone want to make such a device anyway? I mean, I've seen it asked here plenty of times before. It just seems rediculous.
 

StopGo

New Member
joecool85 said:
Out of curiosity, why would anyone want to make such a device anyway? I mean, I've seen it asked here plenty of times before. It just seems rediculous.

Maybe just to get a bit of peace and quiet.
 
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