Frequency Modulation tutorial & FM radio transmitter circuit

แชร์
ฝัง
  • เผยแพร่เมื่อ 18 ธ.ค. 2015
  • This video explains what frequency modulation (FM) is and shows a simple low powered FM radio transmitter circuit you can build. It has a range of about 20 meters.
    Check out my webpage for more videos about electronics! www.afrotechmods.com
    PCB: www.oshpark.com/shared_project... Design files: www.afrotechmods.com/FMTransmi...
    Twitter: / afrotechmods
    Facebook: / afrotechmods
  • วิทยาศาสตร์และเทคโนโลยี

ความคิดเห็น • 250

  • @Afrotechmods
    @Afrotechmods  6 ปีที่แล้ว +5

    Interested in learning about wireless power? Subscribers can get up to 80% off my course Wireless Power to the People - Wireless Charging 101 on udemy using the coupon code "TH-cam"
    www.udemy.com/wireless-power-to-the-people-wireless-charging-101/?couponCode=TH-cam

  • @Avionics1958
    @Avionics1958 8 ปีที่แล้ว +130

    Seriously this was one of the best FM tutorial I have seen. thanks!

    • @AV1461
      @AV1461 8 ปีที่แล้ว +2

      +R Vass Yes. And very short as well.

    • @ProXicT
      @ProXicT 8 ปีที่แล้ว

      +R Vass I agree for sure!

    • @SkGow
      @SkGow 8 ปีที่แล้ว

      +R Vass Really..The Best

  • @Ancientlaws
    @Ancientlaws 8 ปีที่แล้ว +26

    i'm actually learning frequency modulation in class. Seeing real world application is soo nice!

    • @private2809
      @private2809 6 ปีที่แล้ว +2

      Real world application is the only way I can learn. I pay attention and take notes during lectures, but seeing something in practice is just way easier for me. Thank god for youtubers.

  • @RAOROCKSTAR1990
    @RAOROCKSTAR1990 8 ปีที่แล้ว +3

    You know just the way to explain electronics. Describing stuff, giving examples, illustrations. Explaining why we can use a certain component and why we must avoid one. I can't believe my teachers made all this look so boring back in college. I am learning more now than I did in college. Thank You! :-)

  • @mohammedfawaz289
    @mohammedfawaz289 8 ปีที่แล้ว +1

    I needed passive filter design so badly and your video helped me a lot and since then I watch your videos.
    Science is simple and beautiful, when my professor taught us filters it was so complicated and I didn't understand it and solved the exam like a machine without understanding but your video opened the gate and it helped me to continue searching until I had completed my EEG brain wave analysing circuit . thanks !

  • @GeekMustHave
    @GeekMustHave 6 ปีที่แล้ว +1

    Just ran across your channel. Loved the presentation style and the technology images, you tie this all together very well. I expect I'll be watching some of you other videos. Keep broadcasting!!

  • @MrChrisKnowlton
    @MrChrisKnowlton 7 ปีที่แล้ว

    Your tutorials are great. I am finally starting to get this stuff.

  • @emilj726
    @emilj726 8 ปีที่แล้ว

    Finally a new video!!
    Where have you been Afrotechmods??

  • @uberDoward
    @uberDoward 8 ปีที่แล้ว +4

    Love your videos, man! Keep up the good work :)

  • @acestudioscouk-Ace-G0ACE
    @acestudioscouk-Ace-G0ACE 4 ปีที่แล้ว

    Very clear and concise, well produced. Thank-you.

  • @goodwill7643
    @goodwill7643 8 ปีที่แล้ว

    I've purchased TDA7000 chip. Going to try it.
    Nice tutorial. Thank you!

  • @thomasclerc5690
    @thomasclerc5690 8 ปีที่แล้ว

    great video ! i'm glad you grew this much already

  • @koffyolomide_mopao4350
    @koffyolomide_mopao4350 7 ปีที่แล้ว

    i m speechless ... this clear than water ... i subscribe

  • @0Bariq0
    @0Bariq0 8 ปีที่แล้ว

    your videos are the best, thank you so much for making them.

  • @manuja2305
    @manuja2305 2 ปีที่แล้ว

    Man this is awsome. this is the video what i was looking for. i had soo much confusion about FM. but you clear them all. cheers!!!!!!!

  • @XXCoder
    @XXCoder 8 ปีที่แล้ว

    Love your channel. :) One of rare captioned ones.

  • @akcomia
    @akcomia 2 หลายเดือนก่อน +1

    Thankyou so much for this! Just bought the pcb files, and for the informational video!

    • @Afrotechmods
      @Afrotechmods  2 หลายเดือนก่อน +1

      Yay! I am glad more people are making it.

  • @topten7064
    @topten7064 4 ปีที่แล้ว +1

    Before showing your video is great, amazing, clear and thank you very much

  • @johnalvarez7499
    @johnalvarez7499 8 ปีที่แล้ว

    Best tutorial ever; now I'm going to go jam radio receivers with the sound of my gas generator I'll be using to power the transmitter xD

  • @jimadams2473
    @jimadams2473 8 ปีที่แล้ว +2

    Another stellar instructional video. I will be building this myself to better understand the ideas you put forth. $3.00 boards are impressive. I have been spending WAY more than that so thanks for the great tip!!!
    I see you used surface mount components. Tough to do on my bench. I assume the surface mounting reduces stray capacitance and inductance. My breadboard versions usually are a bit tricky to get working especially in the FM range. Anyway, Great video. Thanks!!!!

  • @MbusoYende
    @MbusoYende 8 ปีที่แล้ว

    All hail!! the Afro Tech Mods...this be ruler supreme keys...Soopah

  • @vayunbiyani
    @vayunbiyani 8 ปีที่แล้ว +3

    congrats for your 200k subscribers

    • @Afrotechmods
      @Afrotechmods  8 ปีที่แล้ว +2

      +Vayun Biyani Thank you!

  • @user-cb9rd7dc2q
    @user-cb9rd7dc2q 8 ปีที่แล้ว

    by the way,
    A great site,
    Understandable, clear and pleasant explained
    Greetings

  • @andrewferg8737
    @andrewferg8737 4 ปีที่แล้ว

    Great explanation! Thanks for sharing.

  • @chopcooey
    @chopcooey 8 ปีที่แล้ว

    nice video! inspiring and great practical information

  • @jaffarsyria5206
    @jaffarsyria5206 8 ปีที่แล้ว

    he's finally back

  • @h82sk8
    @h82sk8 8 ปีที่แล้ว +1

    Crazy how I just learned more from this videos then I did in my University class where we built an analog kit version of this.

  • @DeadKoby
    @DeadKoby 8 ปีที่แล้ว

    Cool... FM radio basics. Well explained.

  • @jrausa1
    @jrausa1 3 ปีที่แล้ว

    Hi Afro- I don’t know if you are still monitoring these comments, but I wanted to tell you that I recently built this project, it worked great, and I learned a lot. Thanks so much for going to the trouble to make these great tutorials, provide parts lists and links (no one else does this that I know about), along with clear explanations, working designs, and even a good sense of humor. You really are the best. PLEASE COME BACK!

    • @Afrotechmods
      @Afrotechmods  3 ปีที่แล้ว +1

      yay I'm glad at least one person built it

    • @jrausa1
      @jrausa1 3 ปีที่แล้ว

      @@Afrotechmods Yup, I built the AM transmitter too. One question if I may- could a novice design the PC board for the FM transmitter, just being careful to keep leads short and use a ground plane? Or were there other considerations necessary to avoid parasitics? Thanks again for a great channel.

    • @Afrotechmods
      @Afrotechmods  3 ปีที่แล้ว +1

      It already sounds like you know enough to know what you are doing with the PCB so go for it

    • @jrausa1
      @jrausa1 3 ปีที่แล้ว

      @@Afrotechmods Thanks again!

  • @PraveenKumar-pu4nz
    @PraveenKumar-pu4nz 7 ปีที่แล้ว +1

    you are awesome !Please make a video on phase locked loop.

  • @seancsnm
    @seancsnm 8 ปีที่แล้ว

    This is really cool. I just might try this.

  • @easyelectronics4364
    @easyelectronics4364 4 ปีที่แล้ว

    This guy is genuine!

  • @uNabL3
    @uNabL3 8 ปีที่แล้ว

    And he is still alive! :D
    Yay!

  • @stereopolice
    @stereopolice 7 ปีที่แล้ว

    Nice video. Love it. Thanks.

  • @icaroj
    @icaroj 8 ปีที่แล้ว

    great video! (as always)

  • @jpmorgan187
    @jpmorgan187 8 ปีที่แล้ว

    damn love this guys vids

  • @bakuhost
    @bakuhost 6 ปีที่แล้ว

    Great video.

  • @jeffronay5410
    @jeffronay5410 4 หลายเดือนก่อน

    Well done!

  • @keyen3
    @keyen3 8 ปีที่แล้ว

    @Afrotechmods great video. Could you make a similar one that explains single side band?

  • @akarl11
    @akarl11 8 ปีที่แล้ว

    awesome channel!

  • @yessicaalex3106
    @yessicaalex3106 6 ปีที่แล้ว

    Nice video. Thunks

  • @Manawyrm
    @Manawyrm 8 ปีที่แล้ว +2

    A new video :)
    Great! :D

  • @orlandolara466
    @orlandolara466 6 ปีที่แล้ว

    Hi, your videos are the first place I look when i want to know how to connect and use certain electronic components, thank you so much. I was looking at your AM transmitter circuit as well and I have the same question. What IC can I use so that the circuit doesn't necessarily have to be low powered. I want to obtain a longer range, I visit my grand parents very often at their ranch where cellphone reception is difficult to obtain so I think it would be fun to design a circuit for communicating. By the way, I'm an engineering student, I'm mentioning this in case it modifies in any way your response.

  • @sebastiangrijalva4136
    @sebastiangrijalva4136 8 ปีที่แล้ว +14

    Loved the "Naked Gun" reference.

    • @Afrotechmods
      @Afrotechmods  8 ปีที่แล้ว +7

      Thank you! I'm glad at least one person got it!

    • @s31ACE1252
      @s31ACE1252 7 ปีที่แล้ว +1

      Hehe, I'm old enough to know what it was as well. Very nice touch.

  • @leedave5448
    @leedave5448 8 ปีที่แล้ว

    Thats so Nice. thank you

  • @alibehrouz9833
    @alibehrouz9833 7 ปีที่แล้ว

    fantastic good job.

  • @RhetteLawe
    @RhetteLawe 8 ปีที่แล้ว

    Excellent.... I've been wondering about this sorta jam for a while.... I kinda want to use radio waves to power small battery operated devices and AM has voltage spike issues.
    Utilizing FM band might be ok, provided I'm close to a radio tower. (I live in a city so... s'alright.)

  • @eurobum2012
    @eurobum2012 8 ปีที่แล้ว +3

    Can you please make a video on how to build a simple FM receiver?

  • @csedwik
    @csedwik 8 ปีที่แล้ว

    Yes, next video. Thanks :D

  • @abdoxxg36
    @abdoxxg36 5 ปีที่แล้ว

    so nice

  • @danielgreaney3265
    @danielgreaney3265 4 ปีที่แล้ว

    Nice vid

  • @judgenap
    @judgenap 8 ปีที่แล้ว +1

    Brilliant

  • @DefekCs
    @DefekCs 8 ปีที่แล้ว +2

    Nice video!
    By the way, You could include crude, oversimplified overview of PCB layout. For people who never designed any PCB, even a bits and peaces from this info can be useful... helped me a lot at the beginning.
    P.S. - nice Keysight MSO-X 3054T plugin... actually I am totally "pro" in these kind of plugins (You're showing a very good peace of equipment here), but is it sponsored or coincidence to position oscilloscope view such that it is visible enough to give away the equipment? :D

  • @computerlen
    @computerlen 2 ปีที่แล้ว

    You are really good at this. Thank you.

  • @SKC56
    @SKC56 8 ปีที่แล้ว

    Ayyy, new vids

  • @leocat2662
    @leocat2662 4 ปีที่แล้ว +33

    Why does nobody mention the cute cat on the PCB? :D

    • @HKCREATESUNIQUE
      @HKCREATESUNIQUE 4 ปีที่แล้ว

      Hehe

    • @technodruid
      @technodruid ปีที่แล้ว

      Just had to scroll for two seconds to find people mentioning the cat...

  • @justgivemethetruth
    @justgivemethetruth 8 ปีที่แล้ว

    I take it that audio at the end was the actual transmission? Pretty good fidelity if so.
    I've always been interested in the idea of reflecting laser light off a surface that is vibrating with sound frequencies, catching it and reconstructing the audio, like a spy. Can that really be done? It is so sneaky.

  • @ethanrowlette9912
    @ethanrowlette9912 8 ปีที่แล้ว

    Can you make any good book recommendations that would help fortify the knowledge obtainable on your channel in regards to electricity/electronics?

  • @AB-zw5xx
    @AB-zw5xx 3 ปีที่แล้ว

    This circuit worked very well, and is much more stable than a typical L/C circuit with transistor. However, the output power is extremely low (just a few dozen feet at most) versus 150 feet with even a single transistor L/C transmitter. Can you recommend a simple circuit for an RF Amplifier to add onto Pin 6 of the Max 2606? I'm not trying to interfere with anybody's transmission, but simply trying to see if I can achieve a little more distance in this FM transmitter. I like the stability and ease of use of the Max2606 design, but not the output power. I haven't been able to find any decent, yet simple, RF Amplifier circuits on the internet. Thanks for any help you may be able to provide.

  • @michaelshearer4564
    @michaelshearer4564 8 ปีที่แล้ว

    Could this be adapted to use as an FM telephone bug? I had something similar that a friend built back in the 70's. In not sure about he antenna, and the power was taken from the existing line voltage. The range was maybe a block away, max.

  • @nickhill9445
    @nickhill9445 8 ปีที่แล้ว +2

    Another cool way is to oscillate a transistor were the C B junction forms part of the resonant circuit. The C B junction exhibits the varicap efect. By introducing an AF voltage on the collector you end up with modulated RF with a single transistor.

    • @electrobus5095
      @electrobus5095 8 ปีที่แล้ว +1

      Is there any schematic you have? because i want to build it my own ;)

    • @nickhill9445
      @nickhill9445 8 ปีที่แล้ว

      Hi Thanks for the interest. I done this many years ago when sketching circuits in the back of my high school books. Basically an inductor between B and C on a biased NPN bipolar creating a tank circuit. Oscillated at 100Mhz. Supply lead inductance may also have played a role since I wasn't particularly careful about such things :-) I'll have a play and if I re-create it, i'll let you know.

    • @crazy1be
      @crazy1be 7 ปีที่แล้ว

      Were you able to recreate it? ;)

    • @nickhill9445
      @nickhill9445 6 ปีที่แล้ว +1

      Hi. I have re-created the single transistor FM transmitter I mentioned.
      It easily transmits 30 metres without antenna (probably leakage from
      inductor). www.nickhill.co.uk/single_trans_FM_Xmit.html

  • @cali4484
    @cali4484 8 ปีที่แล้ว

    WOW new video :)

  • @thelifeoftravel3575
    @thelifeoftravel3575 8 ปีที่แล้ว

    wow dear nice

  • @DAVIDGREGORYKERR
    @DAVIDGREGORYKERR 8 ปีที่แล้ว

    Just wondering if you use a oscillator driving a 74AC74 in such a way to generate two signals 90 degrees out of phase then use one of the two signals to drive a 74HC4053 configured as a double balanced modulator then put the other signal you generated with the 74AC74 and filter that and add that to the output of the 74HC4053 balanced modulator using capacitor coupling then triple up the resulting signal then feed it through an RF amp then a bandpass filter then et voilà you have an FM transmitter, BTW you need a frequency of around 40MHZ to start with as the 74AC74 phasing generator divides the signal by four so if you want 10.7mhz so you can use a 10.7mhz crystal filter use a 42.8mhz crystal.

  • @user-py8tx8hk5t
    @user-py8tx8hk5t 8 ปีที่แล้ว

    welcome back , are you still using patreon , as i didnt see your vid overthere

  • @simonroman4116
    @simonroman4116 7 ปีที่แล้ว

    Thank very much

  • @jmbasinger
    @jmbasinger 8 ปีที่แล้ว +2

    You mentioned it was easy to catch people trying to drown out FM signals. Would you consider doing a video about how they catch those people? I want to believe they use some totally rad high tech tools

    • @Coolgiy67
      @Coolgiy67 2 ปีที่แล้ว

      He’s lying it’s almost impossible to track so the FCC and your teachers will just tell you it’s easy to track

  • @MyProjectsTV
    @MyProjectsTV 6 ปีที่แล้ว

    I've build one of this unstable transmitters and I have a lot harmonics. Is there a way to prevent that?

  • @charleshendricks8639
    @charleshendricks8639 4 ปีที่แล้ว

    To increase power to the antenna, could you run the output of the MAX2606 through a suitable OPAMP to increase the P2P Voltage and current output? If not, what is a way to increase the power?
    P.S. - I live out in the woods with almost nonexistant radio coverage and several trees. Trying to build a two-way radio for communication when out working in the woods.

  • @hamidsk2573
    @hamidsk2573 3 ปีที่แล้ว

    it is possible to set the FM frequency with a digital circuit such as MCU, I mean digitally change the variables of LC parameters

  • @mehdimahdi1175
    @mehdimahdi1175 7 ปีที่แล้ว

    can youplease explain how video transmisson works ? for exemple for drones they use rf transmission for video but i couldn't finde any information about that ! thank you

  • @Aemilindore
    @Aemilindore 8 ปีที่แล้ว

    thank you for this great video. could you please explain us how the gov authorities catch higher power radio transmitters?

    • @Aemilindore
      @Aemilindore 8 ปีที่แล้ว

      okay. I just noticed a swer is already available here

  • @bronewid4625
    @bronewid4625 ปีที่แล้ว

    hope you see my question
    the point of the video that was delivered, is the greater the power the oscillator gets, the higher the resulting frequency?

  • @goofypettiger
    @goofypettiger 2 ปีที่แล้ว

    If you are tuned to, let's say, 88.1 MHz, then with a 75Khz deviation, what range of frequencies would your voice had been occupying? Trying to understand the math/numbers here. I know about the L+R and L-R sidebands but want to understand what frequency range (low to high) you were transmitting on. Say if you had a spectrum analyzer listening in on the transmission?

  • @bobskie321
    @bobskie321 8 ปีที่แล้ว

    Back then in early 1980s a wireless microphone that can be receive on a regular FM receiver was common. No need a dedicated receiver like today. Some of them are factory set at 90 MHz while others 92 MHz. You can change the frequency by adjusting the potentiometer. Most of them have rage about 100 meters (according to manual). I can't find those type of wireless microphone these days. All wireless microphone that I saw today have a dedicated receiver.

  • @PhattyMo
    @PhattyMo 8 ปีที่แล้ว

    The MAX260x is a pretty nifty little family of chips. Sometimes the differential output is useful.

  • @foxtrot151000
    @foxtrot151000 7 ปีที่แล้ว

    Is there a way to modify this circuit to get a larger range? I'm looking to transmit just a mile or two on an open frequency

  • @jamesrbrindle
    @jamesrbrindle 8 ปีที่แล้ว

    Great tutorial. I assume if you're tuning and stray on a used frequency for a moment then move on you're not in serious trouble. If you continued to transmit on there you are. Direction finding would require a continued transmission right?

    • @Afrotechmods
      @Afrotechmods  8 ปีที่แล้ว +1

      +James Brindle Yeah you'll be fine as long as you aren't trying to be a prankster

  • @Washburn-rr5eh
    @Washburn-rr5eh 2 ปีที่แล้ว

    What RF generators do you recommend for AM/FM ALIGNMENT?

  • @ismailalperkoylu9863
    @ismailalperkoylu9863 5 ปีที่แล้ว +1

    Watch out for tune pin current level pushing 10k to very low resistance might damage IC

  • @DreStyle
    @DreStyle 8 ปีที่แล้ว

    Were were you my friend!?
    I missed your videos.. 😑

  • @bharathg0
    @bharathg0 8 ปีที่แล้ว

    great....!!

  • @mjsnosk8er720
    @mjsnosk8er720 4 ปีที่แล้ว +1

    Hi anyone know why the Tune Pin pad has a wire soldered to it rather than an SMD Cap and ground connection on the board? Do you desolder it once it's tuned? Thanks for the video!

    • @jrausa1
      @jrausa1 3 ปีที่แล้ว

      I think he has added an aux input in the photo. He mentioned that he broke out the Tune pin for this purpose, and that the aux input has to be AC coupled and about 1mv.

  • @capt_fruit
    @capt_fruit 7 ปีที่แล้ว +1

    Also, I'm hav'n some bugs. The output of the VCO isn't actually outputting a waveform, just a 3V signal.

  • @arukshan7
    @arukshan7 8 ปีที่แล้ว

    long time no see

  • @Hellcommander245
    @Hellcommander245 8 ปีที่แล้ว +4

    Now for a stereo multiplex tutorial :D

    • @theLuigiFan0007Productions
      @theLuigiFan0007Productions 8 ปีที่แล้ว

      And yes, it would be great to see a tutorial. Maybe he knows an even simpler circuit.

  • @dylxnchn
    @dylxnchn 7 ปีที่แล้ว

    how do antennas actually work like what wires are they made from? (FM)

  • @Blowcrafter
    @Blowcrafter 8 ปีที่แล้ว

    Why didn't you just use a Tank circuit like in the classic FM-Bug project? For me it was pretty stable (enough for this kind of project) and it gave the same quality and range as yours.

  • @coltx64
    @coltx64 4 ปีที่แล้ว +1

    How do I make a circuit where I want to have the bandwidth of frequencies almost infinitely? way over the FM network? a circuit without "fancy" chips really from the root of how to make something.

    • @charleshendricks8639
      @charleshendricks8639 4 ปีที่แล้ว

      I'm not an engineer, but I would take a look for a VCO with a large range, or take multiple IC's, for example the MAX2605-2609, and set them up so that as you "tune up," you switch from chip to chip. It might also help if you can find a variable inductor, because that sets the broad range.
      Here's a datasheet for the MAX's. Take a look at pages 7-11.
      datasheets.maximintegrated.com/en/ds/MAX2605-MAX2609.pdf
      *Not infinite, but might be able to cover a broad enough range.
      **Again, not an engineer, just an enthusiest working towards and EE degree.
      If none of that works, you could also try creating your own VCO where you could set the theoretical range from 1Hz - 1GHz, if you have the time to tinker.

  • @JohnSmith-he5xg
    @JohnSmith-he5xg 8 ปีที่แล้ว

    What's the purpose of having the DC bias on the Microphone's + line? Isn't it just immediately stripped out by the capacitor?

  • @Billyboy4209
    @Billyboy4209 7 ปีที่แล้ว

    So what would stop a car stereo to stop picking up fm,I am trying to figure out why a 40 year old radio just stopped getting all fm stations but 1,and it comes in just barely. I was listening to it and the stations just faded away. Sad thing is I have a ham certification but you don't really learn anything in the classes other than how to cram for the test

  • @zayifakimkolu
    @zayifakimkolu 8 ปีที่แล้ว

    Is it possible to use a different vco rather than MAX2606. Thanks.

  • @Bruder_chill
    @Bruder_chill 8 ปีที่แล้ว

    pleas make a toturial about antenna design for transmitter and receiver

  • @catsoften
    @catsoften 7 ปีที่แล้ว +1

    0:19 almost as satisfying as the Nintendo switch snap

  • @RiaRadioFMHD773
    @RiaRadioFMHD773 8 ปีที่แล้ว

    Japanese commercial FM band is 76 - 90MHz.
    In Japan, no license is needed for devices with a signal strength of less than 500µV/m at 3 metres.

  • @Spod23
    @Spod23 8 ปีที่แล้ว +1

    Preety good video about FM transmitter. Is there any good FM receiver circuit, that can receive 150-152Mhz? I need that so much and i can't find a good one.

    • @absalomdraconis
      @absalomdraconis 6 ปีที่แล้ว

      For those who don't know, monoaural FM can be received by AM receivers by tuning them to a frequency that's slightly too high or low.
      For more advanced reception, run the antenna signal (preferably preamplified) into a bandpass filter for your range, then run that into a transistor. Choose another leg of the transistor to be the output, and run a _new_ frequency into the third leg: this is produced by the "local oscillator", and causes the transistor's output to be determined by the following formula: output frequencies = [ input frequency, local oscillator frequency, input frequency - local oscillator frequency, input frequency + local oscillator frequency ], for a total of four output frequencies from two inputs. Then you run the output through another filter to remove the frequencies you don't want (hint: what you DO want is input frequency - local oscillator frequency), and finally run the result into a decode module, which can be the diode stage from a crystal AM receiver (just as an example). Tuning is achieved by changing the local oscillator's frequency.
      There are caveats: if ( input freq - local osc freq ) is negative, then it will actually show up as ( local osc freq - input freq ), which can cause multiple stations to tune in at the same time, thereby necessitating an intermediate filter. A fairly sensible way to achieve this is to use multiple stages of this frequency mixing: the first will move the entire range of frequencies to a lower range (because filters work more sharply for lower frequencies), where the majority of the bandwidth will be filtered out (this can be achieved by either tuning the filter, or having a fixed filter and tuning the local oscillator so that the input frequencies you want to keep are placed into the pass band), and then using the frequency mixing trick again to get the isolated frequency down to the range that you want it in. Honestly, I'd suggest 3 frequency mixers, with the first and third, as well as all of the filters, being fixed, and actual tuning being obtained by using the 2nd frequency mixer to move the desired signal into the pass-band of your "channel select" filter. This allows the variable frequency element to be restricted to a single element (the second of 3 mixers), reducing both complexity and cost, and also allows you to obtain multiple elements from a single "channel" by duplicating the 3rd mixer (with a slightly changed frequency, and possibly filter characteristics) for each additional element that you want to obtain from the "channel": FM radio in the US commonly has at least 4 (2 audio for stereo, though the encoding is a bit more complex than just two audio tracks; a plain fixed frequency for stereo detection; and a digital text signal to provide things like song title and alternative station frequencies).

    • @gammaraymonkey
      @gammaraymonkey 6 ปีที่แล้ว

      What for?

    • @muhammadosama3358
      @muhammadosama3358 5 ปีที่แล้ว

      Use colpitts oscillator with varactor diodes...It'll be your VCO, rest is simple.

  • @heckleru2
    @heckleru2 8 ปีที่แล้ว

    hey Afrotechmods,
    Thanks for sharing the pcb design on oshpark. could you please post or share the parts list? Especially the source for the smt variable resistor, and the other parts as well?
    A good place might be over at oshpark along with the pcb.
    thanks
    dwight

    • @Afrotechmods
      @Afrotechmods  8 ปีที่แล้ว

      +heckleru2 It's linked in the video description section...

    • @heckleru2
      @heckleru2 8 ปีที่แล้ว

      +Afrotechmods
      Thanks!
      I should have clicked "show more" and looked there first.

  • @aidanfranits1339
    @aidanfranits1339 8 ปีที่แล้ว

    Can Oshpark make PCBs out of copper clad boards from DigiKey (that is, boards designed for a specific enclosure)? If not, are there any PCB services that do?

    • @theLuigiFan0007Productions
      @theLuigiFan0007Productions 8 ปีที่แล้ว

      They can cut them to pretty much any size you want if your circuit design fits in it.
      And then after they're made they (or you if they don't) can drill holes if you desire for mounting.

  • @allannowak1406
    @allannowak1406 6 ปีที่แล้ว

    How about hho generation on demand using 27 MHz Maxwell bridge plates to trigger isolated gases further into others using half rectified 120v. Electrolytes with membranes to seperate

  • @l4d2160
    @l4d2160 8 ปีที่แล้ว

    +Afrotechmods I'm attempting to figure out how to build an interior light dimming circuit for automobile applications. In some cars, when you shut the door, the interior light dims all the way to off which is a feature I'd like to incorporate into my pickup truck. My interior lighting has all been replaced with LEDs, so I shouldn't have much current to work with. Would a capacitor or two with a substantial microfarad rating be sufficent, or would I need some extra circuitry?

    • @capt_fruit
      @capt_fruit 7 ปีที่แล้ว

      Well you know you could use a capacitor that drains in it's own loop and just use the voltage from that to control a BJT transistor with a high enough current rating