I really want to say Thank You! for showing us all your crazy, funny, useful, interesting, whatever creations, modifications, hacks or plans and ideas. I'm sure you're fueling many of our creative mad scientist inner selves. I love that you're so open about idea's that didn't work out(yet) and that you reach out to your community for help, like so many of us turn to you with our own questions. Seriously, what you are doing is great, please keep on doin' what you're doin'. Thank you.
Hi Ray. Just a quick note of appreciation for your videos. It's such a great pleasure to listen to someone who knows his subject inside and out, and can put the information over with such an easy-going wit and charm. Your pirate radio stories, in particular are priceless.
BTW, that trick of putting a transformer in series also works great for modulating a He-Ne laser. I once tried it with a PA transformer connected backwards to the 8-ohm speaker output of a hi-fi, and the modulation was such that you could actually see the intensity variation.
With a laser diode it's simipler to inject the signal directly into the driver without the need for a transformer. Actually it's possible with a HeNe as well, but a bit more complicated.
interestingly you can do the reverse and create a laser microphone by shining a lazer through a room and then playing the signal you get from a photo diod on a speaker
What if you power a magnetron that way? Would it be FM or AM? You have the DC supply and than you add another microwave oven transformer in series, than pump the desired signal in to the primary of the second transformer... That'd be one cheap ass power amp!
Eviltech Heh, neat one ;-) Probably AM, because the actual frequency of operation of a cavity magnetron (the type used in a microwave oven) is determined by the dimensions of the cavities inside the tube (although accelerating voltage probably would have a slight effect).
I am not an electrical engineer, rather, I spent 8 years in a math department as a student, but I did stumble on some nice addendums to Ben's transmitter that you may be very aware of. First a disclaimer, you may only want to make the last modification if your lost in an Amazon jungle and need a transmitter with a bit of range, otherwise, you have built a device that can run contrary to FCC part 15 regulations. I originally did not have a 'can' oscillator, so I used a 555 timer and although it works with reasonable audio the canned oscillator is a nicer choice and I ordered one. I did not see Ben's diagram on my mobile internet, so I used a standard configuration with an audio transformer for modulation as in Ben's design. At the output I placed a hand wound coil/inductor having an inductance of .25 mH in series with a 50 K ohm pot that then connects to ground. When the pot is at a setting in ohms that I forgot to make note of the open circuit voltage is maxed at roughly 16 volts peak to peak. Without the coil and pot I only had roughly 4 volts peak to peak. The power source I used to drive the 'can' oscillator was 4 double A batteries in series. Additionally the coil/inductor reshaped the output from square wave into sine wave. I next measured the output impedance of the device by measuring the output open circuit voltage and then the output voltage with a 10 K load resistor with my scope and by performing the calculation discovered when the voltage was maximized by the adjustment of the pot the output impedance was 7.7 K ohms. From this I calculated that for a coil/inductor used as an antenna I would need the inductor to have 1.24 mH for its inductance in order to have its impedance match the transmitters output impedance. I then wrapped, close wound, 24 MAWG wire around an 8 inch by 11 inch cardboard box. The number of turns I used was 47 which gave me very close to an inductance for the antenna of 1.24 mH. I then direct connected the antenna to the transmitter with no need for a capacitor because the coil antenna was designed to only be a perfect match at 1000 Khz Once connected I briefly turned on the transmitter to see if I was spot on with my assumptions or out in left field. Apparently I was spot on because the output across the coil antenna read 8 volts peak to peak exactly as it should were the antenna a perfect impedance match for the transmitter. From the measurements made I will determine the transmitter's power which I am reasonably sure is in the mW range. Once this is known, should the transmitter exceed Part 15 regulations then by adjusting the 50 K pot I can bring the transmitter within FCC guidelines, but still maintain the maximum range for use as a device to transmit audio books which had been the aim of the entire endeavor.
Man whenever you start talking about the electronics behind it, capacitor here, oscillator there and show some circuit layout I'm just lost :D I still love watching your stuff, but that to me is just magic you do because you're a wizard...
I saw this video at random. I found it very cool but over my head. I build cars and trucks and have three with original am radios. I would love to hear music like that come from them. thanks
Wow, so you're really giving the anodizing thing a shot! I hope it works! You probably ran into the paper below already, but in case you didn't, I think it clarifies quite a bit about the process. Great video, btw -- I didn't know AM modulation could be this simple. G.E. Thompson, "Porous anodic alumina: fabrication, characterization and applications", Thin Solid Films 297 (1997) 192-20.
Ben, I know this comment is ~2 years late, but those Superpressure fittings are really nice to use in extreme pressure set-ups. I look forward to seeing what you come up with for your extreme pressure chamber. This is the second time that I've watched this video, so I hope that I didn't write the same comment a year or two ago!
That is SO CREEPY, when you showed the picture of your truck, what went through my mind was moonlight serenade, then you played it to test your transmitter. Ugh I have goosebumps now.
All that AM Tx needs now is some sort of sensor that can detect when you're driving under bridges and whatnot and have it reduce the output of the Tx until you get static.
Great project. Love the MP3 FM radio. Thanks for the tip. I would put a simple pi filter on the output of the oscillator to knock down any harmonics. I know its low power. But, if it can get you into trouble somehow, it probably will. Or not. That loop through junction means you are broadcasting to nearby cars from the truck's antenna. Just thinking out loud.
I'd say be careful to not interfere with other people's radio when transmitting, especially if you have harmonics, but from the sounds of it you'd just be giving them better radio to listen to anyway! :) Nice explanations.
RimstarOrg it's only powerful enough to work from a few feet away. It wouldn't even work to the cat next to you at a stop light. otherwise, it would be illegal.
ricarleite A lot will depend upon how much of the oscillator's square wave remains, and hence the harmonics, though I would expect the transformer to largely smooth that out into much more of a sine wave. One will want to ensure that they are well within the emissions limits, both power and purity wise, for unlicensed transmitters (FCC part 47 IIRC) though it is likely fine if the maximum swing is a volt or less (but I haven't done the math either, nor do I know the total impedance to make the calculation properly). I would likely be more concerned with the DC-DC converter in his truck (the silver module sitting atop the speaker) as I know they produce a lot of RFI as I use one to produce the 19V I need to run a pair of 27" HD monitors for my amateur radio shack where everything runs entirely off of a large 12V battery bank. I had to include a good deal of filtering to clean up its switching transients in the LF through HF brands as well as some LC ringing up in the VHF range at around 80MHz and I could pick up the emissions on my dual band general coverage HT from several tens of feet away. But after filtering it is absolutely quiet now with no detectable RFI escaping my filter and chassis and has worked beautifully.
the problem with the inline setup you have there is that the signal wont just go into your radio but will also be radiated back up the antenna lead and out of the antenna
This is the coolest idea. I was going to hack my old radio and wire an MP3 player with old recordings but I love using the radio exactly as it is so I'm going to try this. Thanks for sharing your ideas. Great truck by the way also.
That anodizing idea is pretty neat, but I have an even better suggestion: experiments at my University have shown that superior adhesive joint bond strength is obtained by boiling the aluminium in MilliQ water. This creates an even more columnar topography and suits adhesive bonding much better than any other surface treatment out there. the only reason it isn't used widely is that industry will struggle to keep contaminants out of the process and ultra high purity water.
You need to mix in some old-timey radio advertisements and announcer breaks with the music mp3 files to really get that 30s AM radio feel. Maybe some Roosevelt fireside chats to listen to?
Yes. It is fantastic! I've posted a couple short vids to twitter, but will wait until the Kickstarter for a full UA-cam video. I saw that you have one as well -- your high-speed bullet footage must be really great!
I started using it the day after I got it, even before I got the batteries for it. I didn't realize the little cap on the body was an ADAPTER so I shot everything without it. I asked David why I could ONLY focus on stuff when the lens was zoomed all the way. lol I thought the lens was broken because the one he sent had a dent. I'm eager to see what others can do with the camera.
if your only using one channel out of the mp3 player module, stereo audio will sound missing/hollow - i modded one in to a flight remote control, with speakers replacing the sticks, they're great, got one with bluetooth built in too.
There are commercial option for this, maybe not as fun as making one from scratch but much more accessible for people who aren't operating at the upper end of the skill curve. It's called SSTran. I use it to broadcast Old Time Radio MP3s through my restored wooden radios.
I threw together a transmitter like that one Friday afternoon, when I needed to trace a cable inside a wall. You can just couple the signal into the live wall socket or whatever with Y caps. I think I used a 555 to create the modulating tone for the oscillator module.
you never disappoint especially since you leave us wanting more and the about a month wait. I don't mind it's worth it to see cool projects like yours. Also with the gecko tape have you gotten any adhesion or just abnormally low adhesion? I had an idea to make my own by focusing a dot matrix onto photo resist, etching copper, and casting that. I would try that I'd the anodized aluminum doesn't work but you seem like you know much more than I do about this.
Great project! (The truck's pretty boss, too). You should set it up so the AM-P3 transmitter turns on/off with the radio itself. First solution that comes to mind is a relay in series with the radio's VBAT line. Also, I would like to see more about the radio restoration itself (or was that covered on one of your other media outlets?)
I've played with this oscillator-can-as-a-transmitter idea a fair bit,and it actually works fairly well. There's a circuit with an LM386 to modulate the power to the oscillator can,also. It can be tricky to find the oscillators in 'useful' frequencies though. (unless your local AM market is completely dead,and 1000khz is clear.)
These MP3 / FM modules are also able to play PCM WAV files at 44,1Khz 16 Bit. So you're not limited to to MP3 / WMA and FM Radio. You could play linear PCM WAV files from the SD card and USB port.
Funny deja vu for me: I also made such an AM transmitter a long time ago but used an NPN transistor and resistor at the output for the modulation. Never thought that those were even stable when modulating the supply directly.
The LM324 has an output voltage range of 0 to V-1.5, and the input high is V-2. Since you set the gain to 2 and the input voltage swings around 1.5v, I think you're probably losing some modulation, the modulation is uneven, and the oscillator drive is a bit low. The input is railing at 3v, but after amplification, the 3v is 3.5v and the 1v input is 2v output, leading to about 1.5v of total modulated bandwidth and an asymmetric amplitude. You might want to use an adjustable regulator with a 6.5v output so that you can get full modulation.
You are correct. I had actually used an LM78L09, and only remembered it as a 5V. This is one problem with building something, then only getting time to make a video a month later :)
Very cool. Might I suggest you change the input of the op amp to be a summing node so you can bring both audio channels into your TX? I suggest this, as some music is very heavily channelized, and you can miss a lot listening to only one channel.
Wow, that's a really cunning circuit. I bet you could capacitive couple to the adjust pin of an LM317 or the like to an audio signal. Then you wouldn't need the transformer (for that circuit) or need to hack the mp3
Really nice project! You probably should add some input filtering. Car power usually has quite a bit of spikes from inductive elements ranging far outside 12 V. This kills the circuit.
Really looking forward to those upcoming projects. I absolutely love this channel Ben.
Thanks so much! I've been super busy with work, but will eventually get to these projects.
Woow, do you have another work other than youtube. I thought youtube is your main job. How you had time to built such a lab at home??
not sure what he does now, but i believe a few years ago he ran a home based repair business fixing technical stuff like MRI machines.
bmetal2 From what I've read from the comments here on UA-cam, he used to work for Valve Software and currently works for Google X.
I thought Myth Busters would have been a good fit, I reckon Google X is even better
"I wanted an old radio, so I bought a 1938 Ford Pickup." Love it.
that trucks looks really nice!
+1
+1
The truck is not an upcoming project?! Some of us are into cars too!
didgitalpunk fuck all of you
Man its so friggin awesome to see chronos cameras just landing in everyone's lap
This could be really handy as I have a studio full of old AM radios. Thank-you.
I really want to say Thank You! for showing us all your crazy, funny, useful, interesting, whatever creations, modifications, hacks or plans and ideas. I'm sure you're fueling many of our creative mad scientist inner selves. I love that you're so open about idea's that didn't work out(yet) and that you reach out to your community for help, like so many of us turn to you with our own questions. Seriously, what you are doing is great, please keep on doin' what you're doin'. Thank you.
I love your off-the-wall approach to problems. Not everything has to be done by the book using expensive parts. Keep up the good work!
Hi Ray. Just a quick note of appreciation for your videos. It's such a great pleasure to listen to someone who knows his subject inside and out, and can put the information over with such an easy-going wit and charm. Your pirate radio stories, in particular are priceless.
Uh, what? His name isn't Ray and he hasn't done any videos on pirate radio. Did you comment on the wrong video?
That's a beautiful truck you have. I love the old music playing over the old radio must be like driving a time machine
Your taste in vehicles is impeccable.
Amazed when you said your friend built that high speed camera. It looks great! Can't believe it wasn't factory built.
BTW, that trick of putting a transformer in series also works great for modulating a He-Ne laser. I once tried it with a PA transformer connected backwards to the 8-ohm speaker output of a hi-fi, and the modulation was such that you could actually see the intensity variation.
That sounds really cool. I'll bet it would work with modern high-power laser diodes too.
With a laser diode it's simipler to inject the signal directly into the driver without the need for a transformer. Actually it's possible with a HeNe as well, but a bit more complicated.
interestingly you can do the reverse and create a laser microphone by shining a lazer through a room and then playing the signal you get from a photo diod on a speaker
What if you power a magnetron that way? Would it be FM or AM?
You have the DC supply and than you add another microwave oven transformer in series, than pump the desired signal in to the primary of the second transformer... That'd be one cheap ass power amp!
Eviltech Heh, neat one ;-) Probably AM, because the actual frequency of operation of a cavity magnetron (the type used in a microwave oven) is determined by the dimensions of the cavities inside the tube (although accelerating voltage probably would have a slight effect).
I felt like I've been waiting a thousand years to see your videos
Admittedly, I can't always follow the content of this channel but it's still very intriguing. love that truck
I am not an electrical engineer, rather, I spent 8 years in a math department as a student, but I did stumble on some nice addendums to Ben's transmitter that you may be very aware of. First a disclaimer, you may only want to make the last modification if your lost in an Amazon jungle and need a transmitter with a bit of range, otherwise, you have built a device that can run contrary to FCC part 15 regulations.
I originally did not have a 'can' oscillator, so I used a 555 timer and although it works with reasonable audio the canned oscillator is a nicer choice and I ordered one.
I did not see Ben's diagram on my mobile internet, so I used a standard configuration with an audio transformer for modulation as in Ben's design. At the output I placed a hand wound coil/inductor having an inductance of .25 mH in series with a 50 K ohm pot that then connects to ground. When the pot is at a setting in ohms that I forgot to make note of the open circuit voltage is maxed at roughly 16 volts peak to peak.
Without the coil and pot I only had roughly 4 volts peak to peak. The power source I used to drive the 'can' oscillator was 4 double A batteries in series. Additionally the coil/inductor reshaped the output from square wave into sine wave.
I next measured the output impedance of the device by measuring the output open circuit voltage and then the output voltage with a 10 K load resistor with my scope and by performing the calculation discovered when the voltage was maximized by the adjustment of the pot the output impedance was 7.7 K ohms. From this I calculated that for a coil/inductor used as an antenna I would need the inductor to have 1.24 mH for its inductance in order to have its impedance match the transmitters output impedance. I then wrapped, close wound, 24 MAWG wire around an 8 inch by 11 inch cardboard box. The number of turns I used was 47 which gave me very close to an inductance for the antenna of 1.24 mH. I then direct connected the antenna to the transmitter with no need for a capacitor because the coil antenna was designed to only be a perfect match at 1000 Khz Once connected I briefly turned on the transmitter to see if I was spot on with my assumptions or out in left field. Apparently I was spot on because the output across the coil antenna read 8 volts peak to peak exactly as it should were the antenna a perfect impedance match for the transmitter.
From the measurements made I will determine the transmitter's power which I am reasonably sure is in the mW range. Once this is known, should the transmitter exceed Part 15 regulations then by adjusting the 50 K pot I can bring the transmitter within FCC guidelines, but still maintain the maximum range for use as a device to transmit audio books which had been the aim of the entire endeavor.
This channel is pure goodness.
Thanks a lot for the time you take to do these video.
Glad to have you back Ben!
Man whenever you start talking about the electronics behind it, capacitor here, oscillator there and show some circuit layout I'm just lost :D I still love watching your stuff, but that to me is just magic you do because you're a wizard...
I am so pumped about the cable modem teardown thingy. Looks really interesting!
Nice to know you have the fire extinguisher close in case this project goes bad.
Simply wonderful .You are, quite possibly, the most amazing person I have come across in my years internetting.
Great job, bro. I love the minimal part count.
I love the truck!! Back in the days when vehicles had style ;-)
9:19 wow the new version of Fallout is looking amazing
its been forever, glad to see your videos again :)
You made my brain ache recalling those lessons from too long ago! Thank you :)
So excited to have you back Ben!
I saw this video at random. I found it very cool but over my head. I build cars and trucks and have three with original am radios. I would love to hear music like that come from them. thanks
They never told me this video would feature so much win. Very cool
A wonderful setup for a beauty of a truck. Thanks for posting.
I really enjoyed the AM radio project Ben! Can't wait to see what you do with that pressure chamber!
Wow, so you're really giving the anodizing thing a shot! I hope it works! You probably ran into the paper below already, but in case you didn't, I think it clarifies quite a bit about the process. Great video, btw -- I didn't know AM modulation could be this simple.
G.E. Thompson, "Porous anodic alumina: fabrication, characterization and applications", Thin Solid Films 297 (1997) 192-20.
Damn I love this channel, that truck looked mint too, looking forward to the upcoming content.
Your oscilloscope is remarkable. Quite the resolution!
Ben,
I know this comment is ~2 years late, but those Superpressure fittings are really nice to use in extreme pressure set-ups. I look forward to seeing what you come up with for your extreme pressure chamber. This is the second time that I've watched this video, so I hope that I didn't write the same comment a year or two ago!
That is SO CREEPY, when you showed the picture of your truck, what went through my mind was moonlight serenade, then you played it to test your transmitter. Ugh I have goosebumps now.
All that AM Tx needs now is some sort of sensor that can detect when you're driving under bridges and whatnot and have it reduce the output of the Tx until you get static.
Great project. Love the MP3 FM radio. Thanks for the tip. I would put a simple pi filter on the output of the oscillator to knock down any harmonics. I know its low power. But, if it can get you into trouble somehow, it probably will. Or not. That loop through junction means you are broadcasting to nearby cars from the truck's antenna. Just thinking out loud.
Great video, and as if you didn't have enough awesome projects going, here's my idea for one. Photomultipliers aka night vision goggles.
Or a far-infreared (thermal) camera!
WOW. Love the science but have to say that truck is really great. Love to see more on that.
Yay more cool projects. I always enjoy watching your videos, both the interesting projects and wonderful explanations.
this project is really nice, gets me in the mood to play with antennas and tv signals again. haha
SDR gets me like that every few months. I'm struggling to not get a hackRF or Yardstick atm.
Excellent build! I love the idea of AM radio over you classic car!
Absolutely LOVE, LOVE, LOVE that truck. Awesome.
I'm really looking forward to seeing your high pressure experiments.
really excited to see the high speed photography!
what a fascinating and we'll described vid, most enjoyable! and I certainly am jealous of that little lorry! thanks for sharing.
Ben that truck is BEAUTIFUL!
Man, that is just plain cool! Love it! Love the truck too!
Finally! Hoping to see much more videos!
that old truck looks sweet :)
I'd say be careful to not interfere with other people's radio when transmitting, especially if you have harmonics, but from the sounds of it you'd just be giving them better radio to listen to anyway! :) Nice explanations.
RimstarOrg it's only powerful enough to work from a few feet away. It wouldn't even work to the cat next to you at a stop light. otherwise, it would be illegal.
How many cars with AM will there be on the road?
That's not the problem, but interference with other appliances or electronic equipment.
ricarleite A lot will depend upon how much of the oscillator's square wave remains, and hence the harmonics, though I would expect the transformer to largely smooth that out into much more of a sine wave. One will want to ensure that they are well within the emissions limits, both power and purity wise, for unlicensed transmitters (FCC part 47 IIRC) though it is likely fine if the maximum swing is a volt or less (but I haven't done the math either, nor do I know the total impedance to make the calculation properly).
I would likely be more concerned with the DC-DC converter in his truck (the silver module sitting atop the speaker) as I know they produce a lot of RFI as I use one to produce the 19V I need to run a pair of 27" HD monitors for my amateur radio shack where everything runs entirely off of a large 12V battery bank. I had to include a good deal of filtering to clean up its switching transients in the LF through HF brands as well as some LC ringing up in the VHF range at around 80MHz and I could pick up the emissions on my dual band general coverage HT from several tens of feet away. But after filtering it is absolutely quiet now with no detectable RFI escaping my filter and chassis and has worked beautifully.
Mauro Tamm most car radio actually no one ever use it though
Cool! You should add some mp3 tracks of old news broadcasts. That would really freak out your passengers
You can use a low pass filter to round off the square wave. In some cases it may also benefit from an attenuator.
This channel never cease to amaze me. Thank you for the efforts you put it these videos. Oh, and great pick-up btw. ;-)
the problem with the inline setup you have there is that the signal wont just go into your radio but will also be radiated back up the antenna lead and out of the antenna
Nice truck and great idea on the Am modulator !
Fantastic Ben! If you ever decide to run for president, your slogan could be "Make am radio great again" 🎶🤓
This is the coolest idea. I was going to hack my old radio and wire an MP3 player with old recordings but I love using the radio exactly as it is so I'm going to try this. Thanks for sharing your ideas. Great truck by the way also.
That anodizing idea is pretty neat, but I have an even better suggestion: experiments at my University have shown that superior adhesive joint bond strength is obtained by boiling the aluminium in MilliQ water. This creates an even more columnar topography and suits adhesive bonding much better than any other surface treatment out there. the only reason it isn't used widely is that industry will struggle to keep contaminants out of the process and ultra high purity water.
Good work Ben, you and Mr Carlson are my fav always look forward to your new vids.
Kind regards from New Zealand.
Paul R
ZL2CIT
You need to mix in some old-timey radio advertisements and announcer breaks with the music mp3 files to really get that 30s AM radio feel. Maybe some Roosevelt fireside chats to listen to?
n17ikh I wonder if there are internet stations for that. Anyone know?
Have you had a chance to play with the Chronos?
Yes. It is fantastic! I've posted a couple short vids to twitter, but will wait until the Kickstarter for a full UA-cam video. I saw that you have one as well -- your high-speed bullet footage must be really great!
I started using it the day after I got it, even before I got the batteries for it. I didn't realize the little cap on the body was an ADAPTER so I shot everything without it. I asked David why I could ONLY focus on stuff when the lens was zoomed all the way. lol I thought the lens was broken because the one he sent had a dent. I'm eager to see what others can do with the camera.
TAOFLEDERMAUS holy shit. Fancy seeing you here. Love your channel.
wow Ive came with a really great idea of anodizing Aluminium fo geko tape!
made my day
if your only using one channel out of the mp3 player module, stereo audio will sound missing/hollow -
i modded one in to a flight remote control, with speakers replacing the sticks, they're great, got one with bluetooth built in too.
I am really interested in that high pressure stuff. can't wait to see what can be done with that.
You, fine Sir, are every bit as AMAZING and talented as God created you to be, God bless you and thank you for these superb works of passion. :)
That Peltier device project look pretty exciting. It would be awesome if you could give an overview of how they operate.
That is so cool. I wish I had that set up in my 51 Chevy. 😎
Video lecture for the day, check! Great video as always! Oh and what a beautiful truck!
WOOO finally, been missing this channel.
Holy shit! You're going to be doing some amazing with this new gear!
Wonderful sir and very well narrated.
Nice project!
Absolute delight watching your videos Ben if you are ever in London doing a demo I will be 1st in the line.
There are commercial option for this, maybe not as fun as making one from scratch but much more accessible for people who aren't operating at the upper end of the skill curve. It's called SSTran. I use it to broadcast Old Time Radio MP3s through my restored wooden radios.
I threw together a transmitter like that one Friday afternoon, when I needed to trace a cable inside a wall. You can just couple the signal into the live wall socket or whatever with Y caps. I think I used a 555 to create the modulating tone for the oscillator module.
Very nice. Would love to see those projects you mentioned.
you never disappoint especially since you leave us wanting more and the about a month wait. I don't mind it's worth it to see cool projects like yours. Also with the gecko tape have you gotten any adhesion or just abnormally low adhesion? I had an idea to make my own by focusing a dot matrix onto photo resist, etching copper, and casting that. I would try that I'd the anodized aluminum doesn't work but you seem like you know much more than I do about this.
@AvE will love the high-pressure stuff...
Great project! (The truck's pretty boss, too). You should set it up so the AM-P3 transmitter turns on/off with the radio itself. First solution that comes to mind is a relay in series with the radio's VBAT line. Also, I would like to see more about the radio restoration itself (or was that covered on one of your other media outlets?)
I've played with this oscillator-can-as-a-transmitter idea a fair bit,and it actually works fairly well. There's a circuit with an LM386 to modulate the power to the oscillator can,also. It can be tricky to find the oscillators in 'useful' frequencies though. (unless your local AM market is completely dead,and 1000khz is clear.)
Something like this: s10.postimg.org/ji5u5f7l5/lm386final.jpg
@@PhattyMo Can I kindly ask you to re-upload that image?
These MP3 / FM modules are also able to play PCM WAV files at 44,1Khz 16 Bit. So you're not limited to to MP3 / WMA and FM Radio. You could play linear PCM WAV files from the SD card and USB port.
The view with it playing from the truck just had me thinking 'Strait outa fallout'. lol
I understood very little of what you said (I'm a mech tech, electronics mean little to me) but it all looks VERY cool!
I like your taste in music!
I have an old Philco cabinet that is crying out for this solution. Thanks!
Vintage truck retrofited with mp3 player, vintage electronic microscope retrofited with slow scan video capture computer, you have the perfect life.
Funny deja vu for me: I also made such an AM transmitter a long time ago but used an NPN transistor and resistor at the output for the modulation. Never thought that those were even stable when modulating the supply directly.
I LOVE THE MUSIC YOUR PLAYING I TYPE IN ALL CAPS BECAUSE OF MY BAD EYESIGHT
Nice pickup and project.
You should download some recorded broadcasts of old AM radio dramas to put on that SD card!
The LM324 has an output voltage range of 0 to V-1.5, and the input high is V-2. Since you set the gain to 2 and the input voltage swings around 1.5v, I think you're probably losing some modulation, the modulation is uneven, and the oscillator drive is a bit low. The input is railing at 3v, but after amplification, the 3v is 3.5v and the 1v input is 2v output, leading to about 1.5v of total modulated bandwidth and an asymmetric amplitude. You might want to use an adjustable regulator with a 6.5v output so that you can get full modulation.
You are correct. I had actually used an LM78L09, and only remembered it as a 5V. This is one problem with building something, then only getting time to make a video a month later :)
I completely forgot why and when I subbed, but man, i m not disappointed!
Ben, I'm looking forward to all the upcoming projects, especially high-pressure hydraulics and gecko tape!
... and cool on the cable modem stuff... I've just got hold of old one of those.
Very cool.
Might I suggest you change the input of the op amp to be a summing node so you can bring both audio channels into your TX?
I suggest this, as some music is very heavily channelized, and you can miss a lot listening to only one channel.
Wow, that's a really cunning circuit. I bet you could capacitive couple to the adjust pin of an LM317 or the like to an audio signal. Then you wouldn't need the transformer (for that circuit) or need to hack the mp3
Really nice project! You probably should add some input filtering. Car power usually has quite a bit of spikes from inductive elements ranging far outside 12 V. This kills the circuit.
good project! i have a very powerful AM station close to me (80km) it transmits at 15kW so it has no problems reaching me.