For better performance, buy a 1 to 1.5 Mhz oscillator. Connect the computer speaker amplifier to the transformer and make a parallel LC circuit connected in series with the output of oscillator and antenna. With LC circuit the square wave will turn into a sine wave, I saw it on the oscilloscope it works. Use an antenna about 20 meters long. I was able to pick up my signal at a distance of 100 meters. Be careful there may be laws that do not allow broadcasting without a license.
I interfered with my neighbor's radio .... he heard it on his radio...I got my little radio and turned it on and said, "gee, you're right.....must be an alien invasion or something." He does not know I dabble in building little transmitters, for the joy and fun of it, so in my pretended ignorance I suggested, "Maybe we should call the cops or something." He mulled, "Well, I don't know, nah.....the hell with it." Then he offered me a beer. Now you know why I will keep my secret forever, to cover my black lies, his good friendship and the free beers!
I'm happy I could help! Make sure you don't make your transmitter too powerful (don't use too powerful a sound source or too long an antenna.) You don't want to interfere with anyone's radio or communications.
The annotations are already there. Maybe you have annotations turned off? But I appreciate your pointing that out anyway. When I tested that a long time ago, for some reason I got it wrong. I'm glad you liked it.
I'm delighted to hear that it works, and so well too! Thanks for letting me know. I don't know how to make an antenna that can transmit 7 miles and I wouldn't recommend it. Certainly not with this transmitter since it broadcasts on so many frequencies, as I point out in this video. You shouldn't transmit more than a few feet to be sure you're not interfering with anyone else's radio. In many countries there are laws about radio transmission. You should check for where you are.
I really like how your videos have easy to follow instructions, and how you make a follow up videos explaining how it works. I want to be an electrical engineer when I grow up, and I can't wait to make this project!
If you want to look more into am radios, pop open that one in the video, or any one really. Chances are, you'll find what's called a ferrite rod loop antenna. Pretty interesting type as it interacts with the magnetic portion of the radio wave, not the electric as the common whip or wire antennas.
Glad you like it. I glued the breadboard because I didn't want to put too many holes in the wooden board but I screwed the transformer anyway since it weighs more - didn't want it falling off. As for the side rails, I could have sworn one side went all the way and when the other side didn't, I just figured that side was busted. Just rechecked and they go 1/2 way like yours. Looks like annotations are in order. :( Thanks for watching!
If the microphone has and amplifier or you connect it to an amplifier first, then it might work. So your sound card would be the amplifier. I wouldn't guarantee it would work since I don't know the power output of your sound card. It's something I wanted to try but I didn't have anything to plug the microphone into. And thanks! I'm glad you liked my video!
Good demo: 1 thing, AM radio receivers do not use the long stick antenna for AM, they all use an internal ferrite antenna , the stick is only for FM (or SW), so just tune the receiver and rotate it to align it with the magnetic field.
Interesting. Thanks. I'm used to making crystal radios where we use long wire antennas -- though having some AM radio stations nearby, I'm able to use relatively short wires (5 meters).
The side with the most turns is connected to the chip and the side with the least turns is connected to the sound source, the CD player in this case. Other than that, which wires go where doesn't matter.
Yes, that's it exactly. I did look at the voltages on my oscilloscope and it didn't seem high, only 10 or 20 volts, but I didn't really make a mental note. It was pretty cool to see though. I first got the oscillator working and saw the 1.8kHz waveform on the scope. Then I added the sound and transformer and saw the modulated version. It was clear as day, very cool to see! Now that I have a transmitter I can do a video following the waveform from source to earpiece.
I have no experience with them. However, I've heard other people say they've bought from them, including this oscillator chip, and I haven't heard any complaints.
My CD player was a random choice. I'd suggest trying it, though if you have oscilloscope then you could look at the voltage range of the wave coming from the speakers first.
That's a programmable oscillator which means that the frequency it outputs is controlled by the voltage you give it. The voltage we give is varies all the time since it's amplitude modulated (AM). The frequency would be constantly changing. So no, I'm pretty sure you can't use it.
for those of us that don't know much about antenna and are trying to learn it be good to explain what each component is doing. Like why do you need the transformer and the AA batteries?
That's in the shortwave High Frequency radio range. I think that's for marine radio, though I'm not 100% certain. I don't know if a normal AM radio will be able to pick it up on a subharmonic frequency. It'd probably be best to keep searching for something in the right range so you don't interfere with anyone else's signals.
i actually realized you can make one out of a boiler and steam going trough a flute that goes trough a big piezo electric crystal that is connected to a antenna spark gap circuit by using wood as energy source. you can also use a water wheel system that use a bowel to create frequency mechanically by resonant frequency of material and connect that to a piezo crystal. for the voice part we need a piece of graphite in between the arc gap connected to a speaker funnel like a old hearing aid. by speaking into the funnel the graphite will vibrate the current and the bowel or flute will act as carrier wave and the crystal will create the electricity to provide electical power to the contraption. the receiver is just as simple. you use same type aparatus for receiver but as sound will come out the other way but this time the graphite will play the sound instead of sending it. if you can't hear the sound the other end, you need a way to tune the signal by adding some metal to the funnel or crystal electrode and it chould works as a tuner by regulating quantity or pressure to the contact point.
I just built this AM transmitter according to your diagram, and it works! It transmits a very strong clean signal. I used my iphone as an audio source and there was no problem with the volume level.
Cool! Glad to hear you got it working! Just be careful to not transmit too far and interfere with other people's radio. This circuit is especially dangerous in that case since it transmits on multiple frequencies. You don't want to interfere with emergency response systems.
The transformer for stepping up the voltage of the audio signal coming from the CD player. Without it the output of the CD player is only around 1.2 volts peak-to-peak. That's too low given the the oscillator powered by the battery is putting out around 6.3 volts. With the transformer the CD's output it raised to around 10 volts peak-to-peak, which is more suitable for being chopped up by the oscillator. See my "Amplitude Modulation with Simple AM Radio Transmitter" video for diagrams.
Thanks! I would like to make my own oscillator, and might just do that. One of the people who asked for a transmitter video specifically said they wanted one using a chip oscillator so I went this way first. Of course, a variable oscillator would be even cooler.
One question though, is the coil only amplifying the source signal ? If so does that mean if you have a higher power source like 12V and is hooked to a transistor (to act as a amplifier).
You may want to adjust your annotations to say that in this case the long bus rows didn't connect to eachother, but do in some cases. Great explination of the breadboard by the way, those things baffled me when i was younger.
If im not mistaken most whip antennas in am/fm radios are only connected to the fm circuitry. Thus putting the whip antenna near the am transmitter make little to no improvement to signal. Most am/fm radios use a ferrite rod antenna for the am circuitry that is housed inside the radio case. As ferrite rod antennas are directional one must turn the back of the radio to face the desired and get as near as possible to the source to improve reception.
I've no experience with powered AM radios, ones with ferrite rod antennas, but with crystal radios, which get their power from the incoming radio waves themselves, the longer the straight antenna the better, and preferably pointing at the radio station, though that's rarely practical.
I was just saying because around 6:37 it looked like you were trying to improve reception by getting the whip antenna closer to the transmitter's antenna.Either way this is a good informative video. Do you happen to be an amateur radio (Ham)? you seem to know quite a few things that might also correlate with amateur radio.
You got it close. FM and AM antenna are the same, the difference is the frequency. AM being 1khz ideally wants a 150m antenna!! FM@90mhz is happy with 1.58m ish The reason AM is set up like that is to compensate for the lack of an 150m antenna The AM antenna you described is a compromise antenna. Either way the losses in the output of that radio will be mental. But the extend length probably helped. At the power levels being talked about it's all irrelevant anyway as you wouldn't even dare to try and optimise that thing without significant filtering. That said well observed re antenna differences And very cool little project, questionable legality but genuinely know harm in doing the experiment for experiment sake
you used a 1.8 megahertz oscillator in the video.wavelength=(3x10^8)/(1,8x10^6)=166,66 meter. so you need 166,66/4=41,66m antenna. is this true? Did you use a 41,66 meter antenna?
You can use a shorter antenna, mine it very short as you see in this video. It's just not as efficient. However, this is not a circuit you want to use for transmitting more than a few meters since it broadcasts on a bunch of frequencies (harmonics).
I don't have an precise figures for you but what that's about what I did in the video. Just keep in mind that with all the harmonics (the different frequencies) it'll be transmitting on, you may even interfere with other electronics of your own. Also, make sure to keep it very low power, i.e., so you don't transmit any farther, since you'll interfere with other people's electronics. In most countries, transmitting like that is illegal and requires a license. If it's possible you'd transmit farther then look for a better circuit. This one's intended only as a simple, fun, educational thing.
Cool. Yeah, I have trouble showing things without trying to explain the why or how of them. :) If you make this, make sure you don't make it able to transmit too far. You don't want to interfere with other people's radios.
I can add it to the todo list to keep in mind but I went with an AM transmitter so I could receive it on my crystal radio and possibly make another video about AM waves.
I'm no expert on making a full radio. There's a lot that goes into making on properly, not to forget getting a license in some countries. But I do know more power and a longer antenna wire are two things.
I don't know but it's illegal without a license in most countries anyway. That's why I kept the signal weak in the video. It's just fun to experient with.
What kind of electronics can a 1 MHz crystal oscillator, or any crystal that would work for AM, be salvaged from? Thank you for the great tutorial. Cheers
Yeah, I had a few requests so that's why I made it. Just make sure you don't make one that's too powerful and interferes with other people's communication and radio.
this was a great video,but could you please show how to reduce noise that is being transmitted as well as received (by the receiver you made),and how to make an effective antenna (like the circular loop or the delta loop)?
I've asked because on the contrary I've mostly seen FM radio transmitters and very few AM radio transmitters; I would like to use both FM and AM transmitters but unfortunately very few AM transmitters are made.
While this AM transmitter's easy to make, it's actually not a very good one since it transmits on a lot of harmonics. You shouldn't transmit any more than a few feet anyway since you'd interfere with others. In many countries it''s even illegal and requires a license.
Very clear ! Tried this a few months back and it worked well. Got a few osc's from an ancient (early 1990's) PC peripheral card. Range is short but it's fun and easy to wire up :)
It depends on the country. As I say in the video, keep it low power and with a short antenna and make sure you can transmit well only a few feet at the most.
Thanks! It was super fun to do, especially seeing it on the oscilloscope (which of course I didn't put in this video :(). Was that your LM339N? I don't recall a video about a radio transmitter.
I read somewhere that a typical audio transformer has a 12:1 ratio. I'm thinking a 9 volt transformer is closer to this ratio than your 6 volt transformer and may perform better. That's something that might be interesting to compare against your 6 volt transformer. An old 9 volt wall wart style power supply may contain a transformer about the right ratio.
Thanks! Glad you enjoyed this one! You said you made one using a cell and some foil - what kind of cell do you mean? And yeah, those pesky sparks throw out many frequency electromagnetic waves. Cool that you used the Kelvin thunderstorm to test with.
Don't worry, I want to build it for the concept rather than actual functionality. But in theory, if you want to be able to broadcast farther away, what variable(s) would you need to increase (like using more power, a longer antenna wire, a lower frequency, a combination of those, or etc.)?
cool! you should make your own ocilator, whitch is basicly a fast blinker. then you could make it variable frequency, becouse there are alot of schematic on variable blinkers. i think putting smaller capacitor will make it blink faster.
I am making a radio and a transmitter for my school science project. I have all things except crystal oscillator. I searched all stores but can't find a 0.9 to 1.2 MHz oscillator. I found a good 0.8MHz oscillator. Will that work? The 1MHz oscillator has only 2 pins while the 0.8MHz has usual 4.
Oh nah, didn't video it. Built another couple of years ago that used a 1.5V AA, it had a transmit range of about 30ft..lot of fun bending the 4 or 5 turn small copper coil to change the frequency, really hands on that one in an intuitive way ! Found it on one of those 100's of circuits type websites.
Thanks for showing me a simple variable capacitor. I need something to tune a receive loop antenna. I think I can get a value in the range I need with your design.
That AM transmitter is absolutely amazing I'm going to buy all of the stuff from Amazon and I'll give it a go and see if I can make up one of these AM transmitters and they look quite easy to put together and I will give it a go when I get the spare time OK and I'm really into electronics anyhow because I'm a Amateur Radio Operator and I like to make up projects like this all the time plus many other things as well. Great video and a really good demonstration cheers. Stephen M3SNV 73's.
RimstarOrg, I has one of these transmitters and they worked very well.But,now being a ham radio operator i have multiple frequency bands and spectrum. Operating on 1.8 Mc will also cause transmission at the end of our 160 meter band which spans to 1.8-2 Mc. Using it in this case is illegal with out a ham radio license and because am covers 3 Kc ether side off the central frequency(1.8 Mc) you are transmitting even out of our band and in to the narrow band am frequency.To solve your harmonics and sub harmonics you can use a circuit called a pi filter. It uses coils and capacitors to let only the frequency you are transmitting on to be passed.
Also, the resown why the harmonics and sub harmonics are there, is because during oscillation, the oscillator probably has a "virtual tank circuit" ( witch is a coil and capacitor in parallel) and the circuit works by rejecting all frequency expect the one it is tuned to . All of the rejected frequency either go through (harmonics) or so far off tuned frequency, they just dissipated and become week.
K5DVT I'm aware of the issues re transmitting. that's why in the video I advise people to keep transmission distance short, no more than a meter or two distance. I advise people that in my replies to comments too when it sounds like someone is trying to transmit further. And thanks for all the tips. I hope to do a filtered one someday. Also, thanks for the explanation re the probable causes of the harmonics and subharmonics.
Thanks, Samimy. Radio controlled car, able to survive in the sea? Where'd you get that idea from? I like it though. I might leave that one to you, fits better with your awesome channel. :)
I don't have the circuit off-hand, though I did once see a video of it a long time ago on CZcams. You'll have to search for it. It'll have more components since it has to make up for the what's included in the 4 pin crystal oscillator.
i meant 1.5 volt cell..if you like short circuit the cell again and again close enogh to the antenna you can hear faint sparks...not quite loud though..because it is very low voltage but still it is quite satisfactory...
I don't have the one from sci toys, but from the photo on their website it looks like 3 prongs and 2 prongs. In that case use only the outer two of the 3 prong side to go to your sound source. If yours really does have 3 and 3 then I'd suggest trying using just the outer prongs on each side and testing both directions to see what works. Is there anything written on the transformer or did it come with any documentation?
Correct me if i'm wrong, but I think one could theoretically replace the crystal oscillator with a crystal rated for 12 mhz, and transmit in the SW band, or one for .225 mhz, and transmit in the LW band.
There isn't any projection coming from the transmitter. There is some sort of manipulation on other stations when we move the wires around while trying to listen to the CD. We are not sure if it's our audio cable or maybe our transformer? (We have a door bell transformer) Any suggestions?
@@RimstarOrg cool, can you recommend a video guide on how to make your own oscillator? And guide how to make simple transistor as well. I'm trying to understand how all these parts works and if possible manufacture them all then create a finished product using all of them completely 100% handmade.
Sorry, I don't have any recommended video guides off-hand. This book here is the ultimate guide to making your own transistors hpfriedrichs.com/mybooks/ioa/bks-ioa.htm You can buy it from Amazon.
+Greg Mitchell Use a more powerful sound source. PS There's no Reply button under your comment because of your Google+ settings. - go to your Google+ page, - in the top, right corner click on your thumbnail icon, - in the popup that appears, click on "Settings". - for the 2nd question down "Who can comment on your public posts?" set it to "Anyone".
RimstarOrg Ok I fixed the reply settings, thanks for telling me there was a problem. Would the audio output on my computer be any more powerful? Is there a way to amplify the input?
Greg Mitchell I really don't have a feel for the the strength of the audio output of a computer. I suspect it's about the same as the CD player in this video though, since both are used with headphones. There must be an amplifier in PC speakers that makes it louder. You can buy small amplifiers like this one comingsoon.radioshack.com/radioshack-mini-audio-amplifier/2771008.html#.VYM7d0bSnbg or you can make your own like mine here czcams.com/video/JtPwxbOgBHw/video.html
+Electronic Experiments I haven't worked with 2 pin oscillators but from what I read of them a while back you'd have to add more circuitry to get it to work, basically circuitry to make up for what's in the 4 pin oscillator that's missing in the 2 pin oscillator.
I don't have any way of knowing. I suspect if the information's on the web, it's probably in German. Just keep it low power and with a very short antenna that can transmit less than a metre and you won't bother anyone.
Great video(s). In this video It appears you are modulating the voltage to the oscillator using a high voltage signal from the transformer. Is this correct?
1.8 mHz is the bottom of the 160 meter ham band and is illegal to operate there without a license. I know that your oscillator is very low power but it is still possible to radiate a signal several miles at that frequency. You would be better off buying an oscillator for 1.0 mHz you can find them on e-bay for a couple of bucks.
This was only a fun experiment and the time you see it running in the video is the time I ran it for. If I were to make a transmitter that I actually use, I would get a license.
I understand but there are many people out there who may think it is okay to run unlicensed transmitters there. I like your video, I just think that you might put a note to let people know that maybe they should stay in the broadcast band. I have been building AM broadcast band transmitters for many years and I know that sometimes (due to things we can't control) our signals can take off on us...please don't take my comment personally. I only meant to be helpful. Thank you for your response.
I do warn about interfering at 6:50 (it's been a while so I had to check) and I have something in the video description about it, plus, whenever someone asks a question in the comments and it sounds like they're building one, I also pester them with a warning too. Had I thought people would actually make them then I'd have added a big flashing warning to the video. No worries re bringing it up, that increases the chances of someone seeing it in the comments, so it's all good.
What if I want to broadcast myself speaking? Will simply plugging a 3.5 mm computer microphone in instead of the cd player output work? Or will I need some sort of sound card? Nice video!
RimstarOrg How could I improve the range of the transmitter (other than using a longer wire)? I understand I shouldn't broadcast very far, this is just for the sake of learning. Could coiling the antenna wire help?
You can use a stronger sound source to begin with, like a PC speaker amplifier or a stereo amplifier, instead of a CD player. And also use a longer antenna. But it's not a good idea. If you broadcast over a larger area then you may interfere with other people's radio. This transmitter is especially bad since if transmits over many frequencies at once. In some countries it's even illegal to broadcast more than a few feet without a license. So no tutorial :).
I can't say for sure. An audio transformer is designed specifically for audio but since I didn't have one, my transformer was a pretty random selection. A microwave transformer would have a different number of turns on the primary and the secondary so you'd get a different voltage than I did. Having a different number of turns means there would be a different impedance (like resistance but to AC) and so the efficiency would be different.
@@RimstarOrg how would one go about stepping up the power of the broadcast significantly? Would you be able to use an audio amplifier but somehow instead connected to a transmitter? I know that with software defined radios we use low noise amplifiers in line to increase the output power. Of course one should only do such a thing if they were permitted to do so by the FCC and on the proper bands...👍😉
I wouldn't with this circuit. It's fun to play with for very short distances but it broadcasts on too many harmonics to be used anywhere for longer distance.
It would transmit on harmonic or subharmonic frequencies. For the harmonics, multiple 1 megahertz by 2, 3, 4, ... so 2MHz, 3MHz, 4MHz, ... For the subharmonics, divide by 2, 3, 4, ... so .5MHz, .333MHz, .25MHz. And it's pretty sloppy around those frequencies, i.e. a lot of frequencies around them. That's the same as for chip I used, except it's harmonics and subharmonics of 1.8MHz.
that's awesome dude seriously, one day people are gonna wish they had knowledge on how to communicate with one another
For better performance, buy a 1 to 1.5 Mhz oscillator. Connect the computer speaker amplifier to the transformer and make a parallel LC circuit connected in series with the output of oscillator and antenna. With LC circuit the square wave will turn into a sine wave, I saw it on the oscilloscope it works. Use an antenna about 20 meters long. I was able to pick up my signal at a distance of 100 meters. Be careful there may be laws that do not allow broadcasting without a license.
I interfered with my neighbor's radio .... he heard it on his radio...I got my little radio and turned it on and said, "gee, you're right.....must be an alien invasion or something." He does not know I dabble in building little transmitters, for the joy and fun of it, so in my pretended ignorance I suggested, "Maybe we should call the cops or something." He mulled, "Well, I don't know, nah.....the hell with it." Then he offered me a beer. Now you know why I will keep my secret forever, to cover my black lies, his good friendship and the free beers!
I'm happy I could help! Make sure you don't make your transmitter too powerful (don't use too powerful a sound source or too long an antenna.) You don't want to interfere with anyone's radio or communications.
The annotations are already there. Maybe you have annotations turned off? But I appreciate your pointing that out anyway. When I tested that a long time ago, for some reason I got it wrong. I'm glad you liked it.
Thanks Brit! Glad you enjoyed it. Thanks for watching.
I'm glad you liked the video. I do have it on my todo list to do a different circuit with reduced noise but I don't know when I'll get to it.
I'm delighted to hear that it works, and so well too! Thanks for letting me know.
I don't know how to make an antenna that can transmit 7 miles and I wouldn't recommend it. Certainly not with this transmitter since it broadcasts on so many frequencies, as I point out in this video. You shouldn't transmit more than a few feet to be sure you're not interfering with anyone else's radio. In many countries there are laws about radio transmission. You should check for where you are.
I really like how your videos have easy to follow instructions, and how you make a follow up videos explaining how it works. I want to be an electrical engineer when I grow up, and I can't wait to make this project!
If you want to look more into am radios, pop open that one in the video, or any one really. Chances are, you'll find what's called a ferrite rod loop antenna. Pretty interesting type as it interacts with the magnetic portion of the radio wave, not the electric as the common whip or wire antennas.
Glad you like it. I glued the breadboard because I didn't want to put too many holes in the wooden board but I screwed the transformer anyway since it weighs more - didn't want it falling off. As for the side rails, I could have sworn one side went all the way and when the other side didn't, I just figured that side was busted. Just rechecked and they go 1/2 way like yours. Looks like annotations are in order. :( Thanks for watching!
If the microphone has and amplifier or you connect it to an amplifier first, then it might work. So your sound card would be the amplifier. I wouldn't guarantee it would work since I don't know the power output of your sound card. It's something I wanted to try but I didn't have anything to plug the microphone into. And thanks! I'm glad you liked my video!
Instructions unclear, got raided by the FCC
congratulations
this is actually a very probable event
Good demo: 1 thing, AM radio receivers do not use the long stick antenna for AM, they all use an internal ferrite antenna , the stick is only for FM (or SW), so just tune the receiver and rotate it to align it with the magnetic field.
Interesting. Thanks. I'm used to making crystal radios where we use long wire antennas -- though having some AM radio stations nearby, I'm able to use relatively short wires (5 meters).
The side with the most turns is connected to the chip and the side with the least turns is connected to the sound source, the CD player in this case. Other than that, which wires go where doesn't matter.
Yes, that's it exactly. I did look at the voltages on my oscilloscope and it didn't seem high, only 10 or 20 volts, but I didn't really make a mental note. It was pretty cool to see though. I first got the oscillator working and saw the 1.8kHz waveform on the scope. Then I added the sound and transformer and saw the modulated version. It was clear as day, very cool to see! Now that I have a transmitter I can do a video following the waveform from source to earpiece.
I have no experience with them. However, I've heard other people say they've bought from them, including this oscillator chip, and I haven't heard any complaints.
My CD player was a random choice. I'd suggest trying it, though if you have oscilloscope then you could look at the voltage range of the wave coming from the speakers first.
Thanks. It's transmitting on a bunch of frequencies, but as long as you don't transmit far then it's a simple, fun one to make.
That's a programmable oscillator which means that the frequency it outputs is controlled by the voltage you give it. The voltage we give is varies all the time since it's amplitude modulated (AM). The frequency would be constantly changing. So no, I'm pretty sure you can't use it.
for those of us that don't know much about antenna and are trying to learn it be good to explain what each component is doing. Like why do you need the transformer and the AA batteries?
Good questions. I answer them in this follow-up video czcams.com/video/_4-Sx-T6VBc/video.html
@@RimstarOrg the link doesn't work 😭😭😭
That's off. I just tried it and it worked for me. Try this short version of the link czcams.com/video/_4-Sx-T6VBc/video.html
Hello from TN. The link takes me to this same video! I have almost everything for this project. I’m just waiting on the wire to come in.
You're very welcome! I had a few people ask for one but I didn't make a note of whom. At least everyone gets the result.
It's still fairly strong around 6 feet, around 2 meters. I don't want it to transmit any farther since that would interfere with radio stations.
That's in the shortwave High Frequency radio range. I think that's for marine radio, though I'm not 100% certain. I don't know if a normal AM radio will be able to pick it up on a subharmonic frequency. It'd probably be best to keep searching for something in the right range so you don't interfere with anyone else's signals.
You're welcome. I'm glad to hear it helped.
i actually realized you can make one out of a boiler and steam going trough a flute that goes trough a big piezo electric crystal that is connected to a antenna spark gap circuit by using wood as energy source. you can also use a water wheel system that use a bowel to create frequency mechanically by resonant frequency of material and connect that to a piezo crystal. for the voice part we need a piece of graphite in between the arc gap connected to a speaker funnel like a old hearing aid. by speaking into the funnel the graphite will vibrate the current and the bowel or flute will act as carrier wave and the crystal will create the electricity to provide electical power to the contraption. the receiver is just as simple. you use same type aparatus for receiver but as sound will come out the other way but this time the graphite will play the sound instead of sending it. if you can't hear the sound the other end, you need a way to tune the signal by adding some metal to the funnel or crystal electrode and it chould works as a tuner by regulating quantity or pressure to the contact point.
dumbcreaknuller YOU FORGOT THE BALLOON THROUGH THE HAIR STATIC ELECTRICITY FLUX CAPACITOR
I just built this AM transmitter according to your diagram, and it works! It transmits a very strong clean signal. I used my iphone as an audio source and there was no problem with the volume level.
Cool! Glad to hear you got it working! Just be careful to not transmit too far and interfere with other people's radio. This circuit is especially dangerous in that case since it transmits on multiple frequencies. You don't want to interfere with emergency response systems.
@@RimstarOrg Thank you for the words of caution. So far the signal is contained to the interior of my house.
RimstarOrg Please tell me how you managed to do that! I’m doing a science project and I really need a way to transmit sound by a phone. Thanks!
The transformer for stepping up the voltage of the audio signal coming from the CD player. Without it the output of the CD player is only around 1.2 volts peak-to-peak. That's too low given the the oscillator powered by the battery is putting out around 6.3 volts. With the transformer the CD's output it raised to around 10 volts peak-to-peak, which is more suitable for being chopped up by the oscillator. See my "Amplitude Modulation with Simple AM Radio Transmitter" video for diagrams.
Thanks! I would like to make my own oscillator, and might just do that. One of the people who asked for a transmitter video specifically said they wanted one using a chip oscillator so I went this way first. Of course, a variable oscillator would be even cooler.
One question though, is the coil only amplifying the source signal ? If so does that mean if you have a higher power source like 12V and is hooked to a transistor (to act as a amplifier).
Welcome! You'll definitely find lots of tech here. I hope you continue to like what you see.
Thanks, my friend. That's good to hear coming from the man with the golden voice!
You may want to adjust your annotations to say that in this case the long bus rows didn't connect to eachother, but do in some cases. Great explination of the breadboard by the way, those things baffled me when i was younger.
If im not mistaken most whip antennas in am/fm radios are only connected to the fm circuitry. Thus putting the whip antenna near the am transmitter make little to no improvement to signal. Most am/fm radios use a ferrite rod antenna for the am circuitry that is housed inside the radio case. As ferrite rod antennas are directional one must turn the back of the radio to face the desired and get as near as possible to the source to improve reception.
I've no experience with powered AM radios, ones with ferrite rod antennas, but with crystal radios, which get their power from the incoming radio waves themselves, the longer the straight antenna the better, and preferably pointing at the radio station, though that's rarely practical.
I was just saying because around 6:37 it looked like you were trying to improve reception by getting the whip antenna closer to the transmitter's antenna.Either way this is a good informative video.
Do you happen to be an amateur radio (Ham)? you seem to know quite a few things that might also correlate with amateur radio.
No, I'm not a Ham operator. My experience in radio is only with crystal radios.
You got it close. FM and AM antenna are the same, the difference is the frequency. AM being 1khz ideally wants a 150m antenna!! FM@90mhz is happy with 1.58m ish
The reason AM is set up like that is to compensate for the lack of an 150m antenna The AM antenna you described is a compromise antenna.
Either way the losses in the output of that radio will be mental. But the extend length probably helped.
At the power levels being talked about it's all irrelevant anyway as you wouldn't even dare to try and optimise that thing without significant filtering.
That said well observed re antenna differences
And very cool little project, questionable legality but genuinely know harm in doing the experiment for experiment sake
Thank you for the suggestion, but I feel the general interest would be too low for that for my channel.
you used a 1.8 megahertz oscillator in the video.wavelength=(3x10^8)/(1,8x10^6)=166,66 meter. so you need 166,66/4=41,66m antenna. is this true? Did you use a 41,66 meter antenna?
You can use a shorter antenna, mine it very short as you see in this video. It's just not as efficient. However, this is not a circuit you want to use for transmitting more than a few meters since it broadcasts on a bunch of frequencies (harmonics).
@@RimstarOrg I want to send the signal with module 2 meters away. How long should the antenna be on both the transmitter and the receiver?
I don't have an precise figures for you but what that's about what I did in the video. Just keep in mind that with all the harmonics (the different frequencies) it'll be transmitting on, you may even interfere with other electronics of your own. Also, make sure to keep it very low power, i.e., so you don't transmit any farther, since you'll interfere with other people's electronics. In most countries, transmitting like that is illegal and requires a license. If it's possible you'd transmit farther then look for a better circuit. This one's intended only as a simple, fun, educational thing.
Cool. Yeah, I have trouble showing things without trying to explain the why or how of them. :) If you make this, make sure you don't make it able to transmit too far. You don't want to interfere with other people's radios.
I can add it to the todo list to keep in mind but I went with an AM transmitter so I could receive it on my crystal radio and possibly make another video about AM waves.
You're welcome, Jona.
Steve from Canada.
I'm no expert on making a full radio. There's a lot that goes into making on properly, not to forget getting a license in some countries. But I do know more power and a longer antenna wire are two things.
With this setup, increased voltage and a much larger antenna how far could the signal travel?
I don't know but it's illegal without a license in most countries anyway. That's why I kept the signal weak in the video. It's just fun to experient with.
@@RimstarOrg u.s.a. limit is 100milliwatts and an antenna less than 10feet long. This transmitter is not illegal. I doubt its more than 100millivolts
Thanks. That's good to know. I hadn't known there was a lower bound.
@@zundfolge1432 99 milliwatts and an 11 foot 9 antenna it is then.
What kind of electronics can a 1 MHz crystal oscillator, or any crystal that would work for AM, be salvaged from?
Thank you for the great tutorial.
Cheers
Maybe look for an old transistor radio.
Yeah, I had a few requests so that's why I made it. Just make sure you don't make one that's too powerful and interferes with other people's communication and radio.
this was a great video,but could you please show how to reduce noise that is being transmitted as well as received (by the receiver you made),and how to make an effective antenna (like the circular loop or the delta loop)?
I've asked because on the contrary I've mostly seen FM radio transmitters and very few AM radio transmitters; I would like to use both FM and AM transmitters but unfortunately very few AM transmitters are made.
While this AM transmitter's easy to make, it's actually not a very good one since it transmits on a lot of harmonics. You shouldn't transmit any more than a few feet anyway since you'd interfere with others. In many countries it''s even illegal and requires a license.
Very clear !
Tried this a few months back and it worked well. Got a few osc's from an ancient (early 1990's) PC peripheral card. Range is short but it's fun and easy to wire up :)
It depends on the country. As I say in the video, keep it low power and with a short antenna and make sure you can transmit well only a few feet at the most.
Glad to hear it! And you're welcome from Canada!
It's a 1 megahertz oscillator which is 1000 kilohertz. That makes it 1000 on the AM radio dial.
You're welcome. I agree, they are pretty interesting.
Thanks! It was super fun to do, especially seeing it on the oscilloscope (which of course I didn't put in this video :(). Was that your LM339N? I don't recall a video about a radio transmitter.
I read somewhere that a typical audio transformer has a 12:1 ratio. I'm thinking a 9 volt transformer is closer to this ratio than your 6 volt transformer and may perform better. That's something that might be interesting to compare against your 6 volt transformer. An old 9 volt wall wart style power supply may contain a transformer about the right ratio.
Thanks! Glad you enjoyed this one! You said you made one using a cell and some foil - what kind of cell do you mean? And yeah, those pesky sparks throw out many frequency electromagnetic waves. Cool that you used the Kelvin thunderstorm to test with.
Don't worry, I want to build it for the concept rather than actual functionality. But in theory, if you want to be able to broadcast farther away, what variable(s) would you need to increase (like using more power, a longer antenna wire, a lower frequency, a combination of those, or etc.)?
Oh I have no idea. The todo list is long. It won't be for a few months at least.
Tried it with a mobile phone, and it seems to work just fine without an amp
cool! you should make your own ocilator, whitch is basicly a fast blinker. then you could make it variable frequency, becouse there are alot of schematic on variable blinkers. i think putting smaller capacitor will make it blink faster.
Thanks. I guess I was making the assumption that some viewers wouldn't know which side is which, so I just told them to try both.
I am making a radio and a transmitter for my school science project. I
have all things except crystal oscillator. I searched all stores but
can't find a 0.9 to 1.2 MHz oscillator. I found a good 0.8MHz
oscillator. Will that work? The 1MHz oscillator has only 2 pins while
the 0.8MHz has usual 4.
Sudipto Ghosh 0.8MHz will work. The normal AM radio range is 0.54MHz to 1.6MHz, so 0.8MHz is right in the middle.
Oh nah, didn't video it. Built another couple of years ago that used a 1.5V AA, it had a transmit range of about 30ft..lot of fun bending the 4 or 5 turn small copper coil to change the frequency, really hands on that one in an intuitive way ! Found it on one of those 100's of circuits type websites.
Thanks for showing me a simple variable capacitor. I need something to tune a receive loop antenna. I think I can get a value in the range I need with your design.
I'm happy I could help. And thanks!
"black usually means negative..." lol ye i can see that in the scociety
If you used a microphone would it work?
You would need a microphone that has a built-in amplifier. So one that takes batteries might work.
You can use carbon microphone connected in series with transformer and battery
That AM transmitter is absolutely amazing I'm going to buy all of the stuff from Amazon and I'll give it a go and see if I can make up one of these AM transmitters and they look quite easy to put together and I will give it a go when I get the spare time OK and I'm really into electronics anyhow because I'm a Amateur Radio Operator and I like to make up projects like this all the time plus many other things as well. Great video and a really good demonstration cheers. Stephen M3SNV 73's.
RimstarOrg, I has one of these transmitters and they worked very well.But,now being a ham radio operator i have multiple frequency bands and spectrum.
Operating on 1.8 Mc will also cause transmission at the end of our 160 meter band which spans to 1.8-2 Mc. Using it in this case is illegal with out a ham radio license and because am covers 3 Kc ether side off the central frequency(1.8 Mc) you are transmitting even out of our band and in to the narrow band am frequency.To solve your harmonics and sub harmonics you can use a circuit called a pi filter. It uses coils and capacitors to let only the frequency you are transmitting on to be passed.
Also, the resown why the harmonics and sub harmonics are there, is because during oscillation, the oscillator probably has a "virtual tank circuit" ( witch is a coil and capacitor in parallel) and the circuit works by rejecting all frequency expect the one it is tuned to . All of the rejected frequency either go through (harmonics) or so far off tuned frequency, they just dissipated and become week.
K5DVT
I'm aware of the issues re transmitting. that's why in the video I advise people to keep transmission distance short, no more than a meter or two distance. I advise people that in my replies to comments too when it sounds like someone is trying to transmit further.
And thanks for all the tips. I hope to do a filtered one someday. Also, thanks for the explanation re the probable causes of the harmonics and subharmonics.
Added to the todo list. Thanks!
Thanks, Samimy. Radio controlled car, able to survive in the sea? Where'd you get that idea from? I like it though. I might leave that one to you, fits better with your awesome channel. :)
Interesting music choice for something like this . It makes it seem like a battle or level in a video game lol
+Raul Rifaie Ronney Yes, it should work with the portable crystal radio. (Please fix your reply button. It's takes extra time to reply in this way.)
What would the circuit be like if there are only 2 pins on the crystal oscillator?
I don't have the circuit off-hand, though I did once see a video of it a long time ago on CZcams. You'll have to search for it. It'll have more components since it has to make up for the what's included in the 4 pin crystal oscillator.
i meant 1.5 volt cell..if you like short circuit the cell again and again close enogh to the antenna you can hear faint sparks...not quite loud though..because it is very low voltage but still it is quite satisfactory...
Oh I doubt it would be mid-June. It takes longer than that just to get the parts through the mail. I guess you'll have to look elsewhere.
I don't have the one from sci toys, but from the photo on their website it looks like 3 prongs and 2 prongs. In that case use only the outer two of the 3 prong side to go to your sound source. If yours really does have 3 and 3 then I'd suggest trying using just the outer prongs on each side and testing both directions to see what works. Is there anything written on the transformer or did it come with any documentation?
You are a scholar and a gentleman and a superlative instructor. Also I made thing and it works. Wow.
Thanks! I'm glad you enjoyed it and found it useful!
Correct me if i'm wrong, but I think one could theoretically replace the crystal oscillator with a crystal rated for 12 mhz, and transmit in the SW band, or one for .225 mhz, and transmit in the LW band.
I would think you could. Just be careful not to interfere with other people's radio.
There isn't any projection coming from the transmitter. There is some sort of manipulation on other stations when we move the wires around while trying to listen to the CD. We are not sure if it's our audio cable or maybe our transformer? (We have a door bell transformer) Any suggestions?
There's a link in the description below this video to scitoys' website where you can order it.
How can you change the radio frequency in your radio transmitter?
For this circuit you'd need a different oscillator.
@@RimstarOrg cool, can you recommend a video guide on how to make your own oscillator? And guide how to make simple transistor as well. I'm trying to understand how all these parts works and if possible manufacture them all then create a finished product using all of them completely 100% handmade.
Sorry, I don't have any recommended video guides off-hand. This book here is the ultimate guide to making your own transistors hpfriedrichs.com/mybooks/ioa/bks-ioa.htm You can buy it from Amazon.
Can I use this as a signal generator
Not really. It produces only specific frequencies and more than one at a time.
cool project! thanks for sharing
This was explained very well. Many thanks for the video!
+Greg Mitchell Use a more powerful sound source.
PS There's no Reply button under your comment because of your Google+ settings.
- go to your Google+ page,
- in the top, right corner click on your thumbnail icon,
- in the popup that appears, click on "Settings".
- for the 2nd question down "Who can comment on your public posts?" set it to "Anyone".
RimstarOrg Ok I fixed the reply settings, thanks for telling me there was a problem. Would the audio output on my computer be any more powerful? Is there a way to amplify the input?
Greg Mitchell
I really don't have a feel for the the strength of the audio output of a computer. I suspect it's about the same as the CD player in this video though, since both are used with headphones. There must be an amplifier in PC speakers that makes it louder. You can buy small amplifiers like this one comingsoon.radioshack.com/radioshack-mini-audio-amplifier/2771008.html#.VYM7d0bSnbg or you can make your own like mine here czcams.com/video/JtPwxbOgBHw/video.html
+Electronic Experiments I haven't worked with 2 pin oscillators but from what I read of them a while back you'd have to add more circuitry to get it to work, basically circuitry to make up for what's in the 4 pin oscillator that's missing in the 2 pin oscillator.
I don't have any way of knowing. I suspect if the information's on the web, it's probably in German. Just keep it low power and with a very short antenna that can transmit less than a metre and you won't bother anyone.
What is the use of a transformer in the circuit? I'm still new to this. Thanks
Sir can you make a on video on how polarized antenna work?
Great video(s). In this video It appears you are modulating the voltage to the oscillator using a high voltage signal from the transformer. Is this correct?
It worked for me, but I can see not having the right transformer being a problem for some.
1.8 mHz is the bottom of the 160 meter ham band and is illegal to operate there without a license. I know that your oscillator is very low power but it is still possible to radiate a signal several miles at that frequency. You would be better off buying an oscillator for 1.0 mHz you can find them on e-bay for a couple of bucks.
This was only a fun experiment and the time you see it running in the video is the time I ran it for. If I were to make a transmitter that I actually use, I would get a license.
I understand but there are many people out there who may think it is okay to run unlicensed transmitters there. I like your video, I just think that you might put a note to let people know that maybe they should stay in the broadcast band. I have been building AM broadcast band transmitters for many years and I know that sometimes (due to things we can't control) our signals can take off on us...please don't take my comment personally. I only meant to be helpful. Thank you for your response.
I do warn about interfering at 6:50 (it's been a while so I had to check) and I have something in the video description about it, plus, whenever someone asks a question in the comments and it sounds like they're building one, I also pester them with a warning too. Had I thought people would actually make them then I'd have added a big flashing warning to the video. No worries re bringing it up, that increases the chances of someone seeing it in the comments, so it's all good.
theres always one person who has a problem with this lol
Instead of the CD player would it be able work with a Logitech speaker thinking it contains the same components?
What if I want to broadcast myself speaking? Will simply plugging a 3.5 mm computer microphone in instead of the cd player output work? Or will I need some sort of sound card? Nice video!
RimstarOrg How could I improve the range of the transmitter (other than using a longer wire)? I understand I shouldn't broadcast very far, this is just for the sake of learning. Could coiling the antenna wire help?
If your tuning into AM radio and you hear somebody singin peanut butter jelly time, Thats me!
You're welcome. And thanks for letting me know.
You can use a stronger sound source to begin with, like a PC speaker amplifier or a stereo amplifier, instead of a CD player. And also use a longer antenna. But it's not a good idea. If you broadcast over a larger area then you may interfere with other people's radio. This transmitter is especially bad since if transmits over many frequencies at once. In some countries it's even illegal to broadcast more than a few feet without a license. So no tutorial :).
Is the antenna just a wire?
Yes, it's just a wire.
Thanks never really made any thing like this before.
Sir, What is the best Antenna for ammature AM Transmission ?
I'm not sure what the best antenna is. I've only ever transmitted around a meter with this simple circuit. I have no amateur radio experience.
What difference would using a microwave oven transformer make?
I can't say for sure. An audio transformer is designed specifically for audio but since I didn't have one, my transformer was a pretty random selection. A microwave transformer would have a different number of turns on the primary and the secondary so you'd get a different voltage than I did. Having a different number of turns means there would be a different impedance (like resistance but to AC) and so the efficiency would be different.
@@RimstarOrg how would one go about stepping up the power of the broadcast significantly? Would you be able to use an audio amplifier but somehow instead connected to a transmitter? I know that with software defined radios we use low noise amplifiers in line to increase the output power. Of course one should only do such a thing if they were permitted to do so by the FCC and on the proper bands...👍😉
I wouldn't with this circuit. It's fun to play with for very short distances but it broadcasts on too many harmonics to be used anywhere for longer distance.
@@RimstarOrg What's the point of the transformer?
It would transmit on harmonic or subharmonic frequencies. For the harmonics, multiple 1 megahertz by 2, 3, 4, ... so 2MHz, 3MHz, 4MHz, ... For the subharmonics, divide by 2, 3, 4, ... so .5MHz, .333MHz, .25MHz. And it's pretty sloppy around those frequencies, i.e. a lot of frequencies around them. That's the same as for chip I used, except it's harmonics and subharmonics of 1.8MHz.
awesome tutorial very educational.
good video too.
next time make a radio controlled car to be able to survive in the sea as well :)