DIY RF Detector Step by Step build | Breadboard #3

This video is a step by step instuction how to build an rf detector on the breadboard.
_____
Follow me on Twitter: ScienceFurry?s=09

[@jaricomusic1604]

Thank you! Please keep the videos coming. Love the work . Definitely subscribed

[@gunnerdavidson7287]

Thank you so much! I was really bored and in need of something interesting to do and this was amazing! The way you described the circuit along with your instructions were very clear! Thank you!

[@itsheiko3549]

0:34 an OpAmp "LM358" is needed

[@kenweeks8039]

Hello again! I have now made an RF detector to your specifications, the idea being to use it to test car RF keyfobs/keycards. It works! Very pleased with the result, although it can be a little tricky sometimes to hold the antenna in the correct 'sweet spot' against the car key fob/card for it to work correctly. One thing that occurred to me when testing the detector - how long should the antenna wire be for best sensitivity? Could the antenna wire sensitivity/reception be improved by coiling it up several times?. When testing the detector with a small hand held (bike to bike) radio, the detector led lights up from several metres away, whereas, a car key fob/card has to be held against the detector for it to work, so I thought that this may be due to the length of the antenna? Many thanks again for your video, Ken.

[@fifaham]

Also we can use Darlington transistor (High Gain) along with RC circuit connected to the antenna and then series that with another Darlington and produce same action.

[@volkinaxe]

that`s a cool thing good job

[@Manaswini0507]

This is great! Can it be used to detect hidden cameras too???? Please reply

[@marcelsolferre3614]

Nice job, it would be nice to measure the signal in hertz format, maybe sending it to the smartphone (frequency counter app)

[@fifaham]

You may add a fixed inductor and a variable capacitors in parallel (multi capacitor banks) (parallel LC circuit > tuner) so you can tune into various frequencies to detect, anywhere from most low to the unity gain (MAX frequency capability of Op Amp) - add this circuit between the bottom of antenna and the the point where two diodes connect.

[@spitfireloverplays6253]

May I ask where did you learn this because I would like to understand why you need those components.

[@RubenMusic_s]

Funciona muy bien..

[@miguelbautista9250]

Que margen de frecuencias puede detectar?.

[@manipulativer]

Yo! Is there a frequency range in which this thing works? I need it to work up to 60Ghz and if its possible to make it more sensitive with different resistors maybe?

[@chatgptrevolution]

How can we make something specific to detect 101.4 khz frequency that they use for Telecom marking underground?

[@daloarabagummoni4746]

Do we add this Saket with ardunio uno??

[@naersthebat4129]

ah yes... a fellow science fur...

[@harlock0974]

Hello ! I successfully built a 40 kHz detector using your circuit. The antenna is an inductor coil and a capacitor tuned to this frequency. I used a TLV2462 as I don't have the LM358. I don't have neither germanium diodes so I directly connect the antenna to the Op-amp pins. I loose the negative part of the signal but it works anyway. The range is very short (

[@tanveernaeem1157]

What is the detectable frequency range of this detector. Thanks.

[@leagueofotters2774]

Will any lm 358 work? 358P, D, M, AD ?

[@stanningeveryone7811]

hello sir. great tutorial. I would like to refer this for my project. my question is, can it also detect the activated RFID tags, the one which already programmed or it can just detect the tags (inactive one/not programmed)?

[@nildocarvalho1471]

Awesome! Thisn detected a running out dog?

[@kenweeks8039]

Hi, do you think this would work for testing a car's remote control (RF) key fob/card? Thanks, Ken.

[@thesciencefurry]

Should work, yes.

[@ChristianvonHausen]

hi, first thx for sharing. can the LM358 be set to detect a specific RF or Frequency?

[@thesciencefurry]

The LM358 is an op amp set up as a comparator. The diodes just rectify whatever Frequency comes in.

[@guilherme6374]

Is not possible to use 1n4148 in the place of 1n34 diode?

[@thesciencefurry]

That's a switching diode not a germanium diode. It could work, but significantly worse if at all.

[@Ibrahim1999]

Hi there , i was wondering about the relation between an antenna's length and the wavelength it can catch , could you tell me ?

[@thesciencefurry]

The perfect length should be 1/2 the wavelenth. But this thing just takes all frequencies and rectifies them. But you can test it out to see if it works better if you have a matched antenna.

[@RanaSengupta]

@@thesciencefurry it should be one fourth of wavelength, as far as my knowledge goes

[@thesciencefurry]

@@RanaSengupta That would work too. It's always 1/2, 1/4, 1/8 etc. But you want to keep it as close to 1/2 as possible.

[@jackevans2386]

Hi, So 1N34 diodes will work OK up at 2.4 GHz ? cheers

[@thesciencefurry]

I think it could get problematic. Check the datasheet what frequency they will work on. But germanium diodes should be more sensitive regardless

[@jackevans2386]

@@thesciencefurry Your Microwave and transmitter work at 2.4GHz

[@Manaswini0507]

Can we replace 1n34 with any other diodes??

[@thesciencefurry]

No, in fact I replaced them at some point with germanium diodes. They should work even better. The diodes need to be rated for high frequency

[@sivanathv9868]

I have setup the exact circuit, but there is no rf detection. Every components are working fine. Could anyone please help me out!! @The Science Furry

[@jankristijan5889]

will this work on 4.5V?

[@thesciencefurry]

I think it should. Try it out.

[@techycharles]

❣️❣️❣️

[@nextnext8902]

Hello, i have done as you said. But my led light is always on. What can i do? (Edit: After this, i have removed diodes and led light still always on) (mine is Lm358L)

[@thesciencefurry]

Did you add the discharge resistor?

[@nextnext8902]

@@thesciencefurry I have uset 470 ohm and 1 Mohm resistors.

[@thesciencefurry]

@@nextnext8902 Try to check if you build it correctly. The 1 MOhm resistor has to be on the right diode. If this doesn't work, try to use another opamp.

[@ikaitg]

@@thesciencefurry Hi, can you explain why we need the 1Mohm resistor? is it maybe to discharge any antenna capacitance that might be holding voltage and keeping comparator saturated or someother reason?

[@thesciencefurry]

@@ikaitg Yeah it's there to discharge any charge that's left.

[@YogeshKumar-im4qw]

इस डिटैक्टर की रेंज कैसे बढ़ाएं।

[@kevinje3971]

Hi, I am confused, why is my led is always on? And why do you need 1M resistor on the non inverting side of op amp and small value on the value of op amp?

[@kevinje3971]

I use coil as the antenna like shown at 0:12 And also when I remove those 2 diodes, the led always on

[@thesciencefurry]

If there is no resistor the led will stay on. Because charge is building up there or something for some reason.

[@kevinje3971]

@@thesciencefurry And why do you need 1M resistor on the non inverting side of op amp?

[@thesciencefurry]

@@kevinje3971 That's the resistor I was talking about in the previous comment.

[@kevinje3971]

@@thesciencefurry okay thanks

[@jaiminpatel4231]

Hey my LED is always on can anyone help what I did wrong here?

[@thesciencefurry]

Maybe decrease the pulldown resistror.

[@jamesmcbrideag5ve743]

I tried the your circuit just as you built it, but with a 4558 instead of LM358 (it's what I had on hand). However, when I plug in the battery, the LED is constantly on, no matter where I am located. Any ideas what I'm doing wrong?

[@thesciencefurry]

Have you tried adding the pull down resistor to the non inverting input? Because it indicates that the voltage on this input is higher then the other one. Maybe putting a potentiometer in place of the resistor helps.

[@jamesmcbrideag5ve743]

@@thesciencefurry No matter what value resistor I connect to the non-inverting pin, the LED is still constantly on. I have also tried several op amps and 2 different input voltages. Even tried reversing the diodes. No luck. I doubt there is a constant source of RF from my radio room in my house all the way to the middle of my street. Thanks for the reply.

[@thesciencefurry]

@@jamesmcbrideag5ve743 Hmm, that is weird.

[@arthurharrison1345]

The 4558 is not necessarily good for sensing very low voltages at its inputs when connected to a single supply. It is designed for dual supplies.

[@NZhTI]

I have Speaker A Sound and Meter

[@YogeshKumar-im4qw]

,this projekt ten feet range honi chahiye।

[@indulgence8860]

So how do you jam signals from the government to not read your brains reflexes.....

[@thesciencefurry]

Tinfoil hat

[@dimitriosa8tsipouras953]

CAN I USE 1N4148? AND NOT 1N34?

[@thesciencefurry]

I think it would reduce the sensitivity a lot, if it works at all. It's not a germanium diode.

[@dimitriosa8tsipouras953]

@@thesciencefurry thank you for the reply, i try the 1N4148 and not works, i try to find the 1N34 but i cannot in mouse or digikey or even in local market. The supply power can be 5V? or should be 9v?

[@thesciencefurry]

@@dimitriosa8tsipouras953 5 volts should work.

[@albin6382]

I hate furries, but nice video.