1 MHz AM Transmitter
ฝัง
- เผยแพร่เมื่อ 4 มิ.ย. 2021
- This video shows how to build a radio that transmits a simple 1 kHz tone on the AM band, which can be heard in a handheld radio or car radio up to 100 yards away. The radio uses an LC oscillator to drive a push-pull amplifier made from a 2N3906 and 2N3904 transistor. The audio tone is generated by a 555 timer. The radio can be powered by up to 40V, but in this video I'm only using 12V.
I experimented with transmitting on 1030 kHz then increased my frequency to 1620 kHz by changing the capacitors in the LC oscillator that generates the carrier wave. Because the frequency is so low in both cases, the antenna is nowhere near the wavelength, or even quarter wavelength. For antennas shorter than L/4, two major problems occur:
-The radiation resistance is extremely small (i.e. only a very small amount of the current in the antenna actually travels out as radio waves)
-The antenna acts as a capacitor and has huge impedance from capacitave reactance. In the video, i attempt to balance out the capacitave reactance with an adjustable inductor (or "loading coil"), with fairly good results.
The total power radiated was well below 1 mW in both cases. This is probably less power than something like a garage door opener transmits.
Note that radio transmissions in the US/Canada/Europe are regulated, and this device is only for demonstration. If you want to build a larger power transmitter, make sure you've got an amateur license and use one of the frequency bands allocated to amateurs.
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i think this video is the best DIY about radio i have ever seen, it takes you step by step and explain why those design choices were made, and how to test what you did, while most of the other designs are like blind design without explanation not testing
iterative design is best way to learn
Well explained. I would generally be cautious though about transmitting square waves as the scope for spurious harmonics, especially without a low pass filter in circuit, is high. And yes, 1 or 1.6MHz transmissions, without a broadcasting licence, are illegal in most countries.
Is it better to just transmit sine waves, and skip the wave “clipping” phase of this project that creates the square wave?
Can't be a Hyperspacd Pirate if you're a Hamm
I do want to get my radio license but how whould the government or related branches know it's me doing this and it's ok? I will make this after I get my license but whould me doing this get people angry Even if I have a license for transmission?
@@kylewatson952 He's talking about transmission in so many YARDS of range, so the amount of power here is tiny, maybe 50-200mW, which will likely get swamped the first time someone with a '68 Cuda running copper core sparkplug wires drives by. :D If you keep your transmission power under 200mW, and avoid sending profanity over the airwaves, try to stay out of active transmission space, and are only playing around 10-20 minutes at a time, nobody will likely notice. As for locating spurious radio emanations, google search the term "radio fox hunts" or ARDF. There are also plenty of public radio space bands to play with, called the ISM bands where you've got all sorts of consumer radio products operating, and oddball modulation schemes like LORA-wan devices, which is low power, low bandwidth, infrequent transmission for whatever gadgets you care to built. Say a bunch of remote weather or telemetry systems that can run off one 18650 battery for a couple of months.
Ya, square waves have infinite harmonics.
After watching several of your videos, I have to say they are some of the best that I’ve seen covering anything remotely more complicated than a “hello world” Arduino sketch. I’ve studied plenty of concepts in college but they always lack in one way or another. You cover the system, the circuit design, and include equations as a bonus! All while keeping the DIY spirit… I’ll gladly listen to the static on your voiceovers for that!😂
Takes me way back to electronics classes in college.
When you said 555, I got chills.
back when integrated circuits weren't dogshit
At 11:13, this capacitance you describe from your hand moving around the antenna is the main theory behind the electronic musical instrument, the Theremin
Thank you so much for this video. Not only did you explain the project well, you made it look doable with the information provided. I've never done anything with RF, but this video just changed that. Time to go build!
new unlock: the ire of the FCC
@@the_7th_sun fox hole hunt
I've always been wanting to build one myself! Now I can, thanks to you! Thanks for showing the way😄
It took me a long time to learn enough about electronics to make a radio work so I'm glad i could help someone else do it
@@HyperspacePirate thank you very much for inspiring the likes of me. Now I get to work again on my fave hobby😄
@@HyperspacePirate how long did you have to learn to actually build radio and understand it? and how did you learn?
Nice! Future projects could be, naturally, voice modulation but also something that would turn on remotely using a specific sequence of pulses like a digital 'key' to trigger something at a distance like a light or something else, digital data like '1', '2', '3' etc., something that remains on as long as it receives the signal, and other fun applications for the receiver.
Welcome back to history, you're almost at the point of reinventing Morse code 🙂
@@metamud8686yeah and it seems that kind of technology has been lost in the dump as there is no information anywhere on how to make a multi channel transmitter and receiver from scratch without using the pre built RF modules and IC’s. What a shame 😢
Your PNP transistor emitter usually connected to +Vin (Vcc)👽 3:42
Great build. Keep up the good work.
Good work! I would improve the schematic 13:28 - between an emitter of Q3 and ground place 10 Ohm resistor (maybe with a capacitor 47nF). R10 change to 10kOm instead of R11 I would place wideband RF transformer: twisted five wires on a NiZn ferrite core (maybe with a small air gap). Three wires (I mean windings) connects in series as a load of Q3, four and five wire connects to an input of the push-pull cascade with the 2N2222 transistor. The bias circuit for 2N2222 contains : a silicon diode (1n4148) with a 1-2KOm resistor to positive rail. Both transistors loads on a wideband output push-pull transformer.Both emitters of 2N2222 connected together and to the ground in series of a 10-20Ohm resistor. The wideband transformer allows matching high impedance of Q3 with low input impedance push-pull output cascade (because a Miller effect in BJT) and increases power amplification.
Very informative, thanks for sharing video, Subscribed
Cool beans.
I've assembled several over time & the last time I just used the 555 timer chip since you can get it to oscillate in the AM broadcast frequency interval. In a sense it sucks because the square wave it produces comes with plenty of harmonics, but I just wanted to play with the idea and indeed I did get licensed as kc2wvb roughly 12 yeats ago and even updated it in 2011.
Amazing Video as always
To be clear, broadcast medium wave antennas are usually hundreds of feet high, but of course a conspicuous 'pirate' antenna setup would be an instant location giveaway. This is a nice demo for experimenters, showing that something can be got out of simple circuit and a tiny antenna. I think an opened out roll of cooking foil, might have been less lossy and would have made a slightly better ground reflector than a vertical ground rod.
When I was a child, built an AM tx using a 2sa15 germanium transistor, 1 ferrite rod, 2 100pf caps and 3 resistors. it ran of 2 dry cells. could be modulated with audio. It worked and was stable. simple colpitts oscillator. tuned by moving the ferrite rod. no external antenna . sufficient signal for use in a small house.
Amplitude Modulation (transmission or reception) is relatively basic as far as radio communication is concerned. I remember in my ET-A School years ago we called Frequency Modulation "Fewking Magic". That said, if/WHEN the SHTF it will be folks that have knowledge like this who knit society back into a (semi)cohesive whole again!
Pretty sure the push-pull amplifier has the npn and pnp swapped round (normally the emitters are connected together, and form the output). Also the 555 usually has pin 2 and 6 connected together in the configuration shown.
It would be interesting to know how much difference the capacitance hat made to the capacitive reactance, radiation resistance and (hence) the transmitted power.
At 1 Mhz the antenna would be an optimum radiator as a long horizontal wire , 20 foot off the ground , that your garden permits ! ( the full wavelength is approx 300 metres / yards !! ) , so a longer antenna is MUCH easier to match at this low frequency ... shorter antennas work best for stuff like CB radio ( 27 Mhz ) ... note : however a super efficient antenna might cause interference in the next state ! ( probably not a good idea ? ? ) .....
Thank you for that video. Very educational. I used to make those when I was a kid but it was always somebody else's schematic diagram and I learned very little. I mean I built it, without really knowing what I was building. I think I'm going to go back and build another one, even though my wife says I'm too old for this.
11:38 Radio by day... theremin by night. Love it.
Where are the side bands. That's what's really going on. It's really neatly done, good on ya m8. Brought back memories from the distant past. 🙂
Why did you clipped the signal? It had a reason or it was a side effect of the amplifying? Also I noticed that the signal before the amplifier/clipping has 9.52V, and then it has 9.68V. It didn't changed that much. This step seems not necessary to me. Can you elaborate more?
(His neighbor trying to listen to his AM radio church program) "What the heck is that noise!!!"
lol
How do you know ?
It was a joke lol @@tonywright8294
It's satan, jamming the emanations of god.
Cool!
The 555 that generates 1 kHz has an error. There is a wire missing that is supposed to connect pins 2 and 6. It won't work without this.
The Q4, Q5, Q6 outputs seem to be out of bounds. The R17 biases Q5 fully on. If the ground wire touched the antenna, the excessive current through Q5 would burn it out. So there should be a DC blocking capacitor, like a .1 uF ceramic disk, in series with L2, to stop the DC.
But the output has too many harmonics. Much of the RF is in the harmonics of the fundamental frequency. They should be removed by a 1.7 MHz low pass PI filter on the output. Without it, there will be harmonics that may be interfering with higher frequencies.
The ground wire is missing in the schematic.
Thanks for the video.
Wouldn't it be possible to make an oscillator with TTL or CMOS chips for the carrier frequency instead of going to the trouble of making a Colpitts oscillator and then an amplifier ?
Awesome video, just found one little mistake in the clipping amplifier schematic, the PNP transistor is placed wrong with the emmitter connected to GND
hi iam very curious, can it produces magnetorestrictive effect if ferrite core+permanent magnet was present in coil arrangement?
if you read about ultrasound generator there are 2 type : piezo(ceramic) n magnetorestrictive(coil) based, both of them commonly work around 30 - 40 khz ranges, yours was 1000 khz!
Where did you ever get the idea that moving electrons release photons?
Finally, someone else mentions this...👍
Please make video about fm transmitter and receiver
Ich habe den Telefunken Detektor im Original.Die Abstimmspule hat 2 Schleifer.💖🇩🇪🤐Einmal die Anpassung der Antenne,das andere die Abstimmung.Alles ohne Drehkondensator.Somit arbeitet sie als galvanischer Transformator selektiver.
could get more current gain on your output pair using a darlington configuration
Wouldn't it be easier to pick a too large inductor for impedance matching and add a variable capacitor in series?
Nice job. Have you tried using transformers for the push-pull amp? They should increase your output considerably.
I haven't yet, but it's high on my to-do list for my next radio project.
@@HyperspacePirate See th-cam.com/video/y8te4Mir_BY/w-d-xo.html I'm still experimenting with an antenna matching network, so the range is limited. 300 feet of 10awg would do the trick, but I can't really justify that expense, nor do I have a broadcast tower in my yard. Ha ha. The coil set up you're using is similar to a crystal radio antenna I built a while back. Have you tried adding a 300p variable capacitor to it?
@@andrewferg8737 that's an impressive setup. I'll need to look at it a couple times to fully understand what's happening, but your approach of inductively coupling your antenna is one i want to try with my next transmitter. I recently got a hold of several ~50-300 pF 3 and 4-gang variable capacitors from some old aircraft radios, so I want to try them out in a future build for tuning
@@HyperspacePirate "inductively coupling your antenna"
The output transformer of the push-pull amplifier is not technically part of the antenna, although electrically it certainly is.
Normally I would put a pi filter between the antenna and that transformer and tune it for maximum output. This works great at higher frequencies like the FM band. I tried it with the 3W base AM transmitter and it works somewhat, but I haven't had any luck at higher power in that frequency range. The 30ft antenna wire seems to dominate the output. I will try a shorter antenna with a large air coil & varicap next.
So, why the square wave output? That would generate a bunch of harmonics and waste energy while creating wideband noise?
i like to shift the carrier by 90degree and mix two IF and the carrier together
hm, might be cool to modify it so it fits into that 160 meter slice of ham, seems pretty close already, so probably pretty simple to get it up to 1.8-ish mhz suitable for CW
Make a receiver video, please 🙏🏾
I have had a working transmitter for a while and can pick up signals with a purchased am radio but I can't seem to make the receiver from scratch
Could you give a link to the site you found that antenna capacitance calculator ? I can't find it and I want to be able to make a good impedance match to get the most out of this circuit.
Oh nvm I saw the link in the bottom-right corner at 08:03
Thank you so much for this! The one question I have is: Why did you go to the trouble of turning the approximate 1mhz sine wave you got out of the Colpitts oscillator into a square wave? I thought that it would have been cleaner and easier to just use the sine wave and maybe filter it a bit to make it look nicer, considering that a sine wave has so many harmonics and all.
I'm pretty inexperienced with RF, so at the time i thought a square wave would be cleaner. After looking at the output of this transmitter on a spectrum analyzer and seeing all the harmonics, it was clear that that's not the case
Ah, right. Thanks for the reply
Any chance of getting the STL/STEP files for the winder and the radio fixture itself? I want to build this.
This sounds like how Marconi started but I have to question the transmition of Photons at 0:46....Photons?, Light?
Now how do you transmit information without waves, from proton to proton?
what is the purpose of ground plane ?
Oh look, a Thermin !
;)
Your CW is QLF (Are you sending with your LEFT FOOT?)
0:01 calling for artillery support ;)
Isnt anything under 100mw ok?
Your PNP Transistor is reversed at 4:14.
Yeah i noticed that in his videos
Maybe this is his style
This remind me of Chinese circuits when they try to protect there knowhow
lol qrp on the commercial AM broadcast band, would be interesting to try sending code at 1700 KHZ to see what you get in return lol. but like you said, you have to be a bit careful not to qrm over top of another station that might be occupying the frequency you wish to use.
you have to broadcast the infamous number station call sign melody "The Lincolnshire Poacher". The best radio value I know is a Baofeng.............$30 has 5km of range.
@HyperspacePirate >>> Great video.
Can you please make a FM Transmitter
Me gustó mucho, tendrás un diagrama de 50wats
in the C equation, what is the value of Len, Fre and Dia you used?
www.everythingrf.com/rf-calculators/whip-antenna-calculator
@@HyperspacePirate do you have any email contact where we can talk?
14:12 … at 1.6MHz you were so close! “160 Meters” band, 1.8-2.0MHz is Amateur Radio. Specifically, 1.800-1.820MHz is for Morse Code transmissions. 😊
🏆🏆🏆
Since you are feeding a 1 MHz square (-like) wave into your antenna you have a plenty of output at 3, 5, 7... Mhz as well.
Now the Americans should start using mouse farts as the unit of measurement for the power of radio waves.
the exact frequncy = 72,948.5 means around 73 Kh
What software do you use to design your circuits?
KiCAD
@@HyperspacePirate thank you :)
Picoferrets and millihenrys lol
..its prolly boring for you but a fancy crystal radio build would be appreciated
hätte gerne eine bauanleiung bitte
why didn't you use another 555 to make the 1MHz ?
Error at 08:39 ? If P=10^-10 Watts, then Log10(P)=-10, and that x10= -9 dBm ? Or am I missing something?
Cause dBm is referenced to milliwatts, so 10^-10 W = 10^-7 mW = -70 dBm
Ah, so that’s what the “m” stands for! Looked it up (just now) at en.m.wikipedia.org/wiki/DBm
@@DavidEsp1 Yeah it can be confusing between dB / dBw / dBm. To add to the confusion, in audio, dB are usually 20*log10(X) instead of radio where its 10*log10(X)
@@HyperspacePirate Yes that one already gotcha-d me. They’re not really different in meaning, both are power, it’s just that in audio-land it’s amplitude (traditionally voltage, now digital) that gets measured and displayed as waveforms (in DAWs and NLEs). So since power is voltage squared (and in log-world squaring becomes doubling)...
@@HyperspacePirate Just don’t get me started on dB differences for mono and stereo ! Loudness levels for mono generally need to be halved (-3 dB) as compared to those for stereo. Based not on simple maths but a messy compromise - in objective reality depends mainly on how identical the sounds on each channel are.
I (and a pro I sought advice from) were “gotcha’d” (in my case badly) by that one (I guess no mono final mixes loudnesses recently experienced in that pro‘s broadcast world).
Is it possible to create an am transmitter without the use of a power supply?
? You mean without a bench power supply?
i mean if there’s a way to transmit radio signals much like how a spark gap transmitter works but without the use of a power source or batteries. I’m no expert on this field, but apparently such a device is possible.
If you see repeating comments it’s because they weren’t going through for me
@@joemawmaw8609
Only example of that I'm aware of is a steam turbine with a generator used to generate AC at the transmitting frequency
en.wikipedia.org/wiki/Grimeton_Radio_Station
@@HyperspacePirate I sent you a link to schematics for such a device that may exist here but TH-cam kept removing my comment for seemingly no reason. I sent you an email with the link if you’re interested, would love to know what you think
The emf is free. I'll not be paying some g-man.
11:46 a little disappointed to not see a fancy 🎩, but I'll let it slide for this time
Why not use a crystal oscillator?
HF is like a dark art to me. I don't understand it and it makes a lot of weird noises.
This once again reminds me that I'm actually stupid
HSP - I have a Question - and I Know you have the ability to answer. I've Subscribed to help your efforts and here's my question and I'm asking for your time yes that's what I'm doing
What would happen if I built a '2 x tower Tesla Coil' - only it has 110 pancake coils making up both towers so that's 2 towers with 110 pancake coils as opposed to a single wire aircoil these have 220 Pancake Air Coils all in 2 stacks - you got that so far?
Now I'm going to be weird and supply all 220 pancake aircoils with 3 different wire supplies and have all 660 wiring circuits all connected to a Really Big Transformer and balance it all off with some capacitors. The Pancake air Coil circuits are going to be 110v at 50 cycles.
Absolutely Not Wired like a Tesla Coil but apart from what is said that's what I want.
Now I'm going to hit those towers with a very powerful 8 Hertz and hold my 8 Herts for over 4 hours.
A. What's going to happen to the 220 pancake coils and structures holding them?
B. What's going to happen to the transformer and all the capacitors?
C. In your own words please describe the environment.
Is this legal as long as it transmits a few feet?
No it’s against the law !
probably why the range is so bad is because the only transmitter schematics you can get is for low power transmitters in the micro watt range.
the fcc and arrl very carefully guards the schematics for transmitters for anything higher than a small fraction of a watt so if you want even to make 5 watt transmitter you need an fcc license and be a radio engineer.
3:55 oh look like you wrong there. PNP E not connect ground like NPN because Ice=minus
Very good video , but you’re microphone makes hashing noise..
Electrons do not release photons when traveling up and down a conductor.
you are also mixing current and power, geez...
Very distorted oscillation
Im willing to bet you had FCC vehicles going around your general area for a day or two after this experiment, trying to find that source of interference.
*The FCC would like to know your location*
1. Put a Vacuum sphere on the top load. Better Signal
2. Just use a pwm to pulse the 1mF coil at 9ms better signal and POWER
3. Most importantly, the ground rod needs to be In between the Inductor and capacitor. All together better Geometry Less parts and materials.
YOUR EXPLANATION of an AM CARRIER is COMPLETELY INCORRECT. Go do some research on single sideband, which is one sideband of AN AM SIGNAL, having removed the opposite SIDEBAND, as well as SUPRESSING THE CARRIER. There is no "envelope," and AM modulation does not affect the carrier as you claim. SIDEBANDS That is the key word
I notice a lot of noise in your audio recordings. Great content otherwise :)
1MHz AM can only be used for rock music, not pling plong electronic music, it simply doesn't sound good.
Привет друзья ищу команду энтузиастов которую тоже хотят полететь в космос и построить ракету для начала если есть желающие и отважные люди пишите мне обсудим этот момент
@Edward Wilson @moojvyin
Still waiting on FCC approval for my spark gap transmitter.
You might wait a very long time. 73 de VE6AEQ
Has the FCC broken down your door and arrested you yet? :p
When they've chased down every other source of spurious radio emissions over 100mW in the country, they'll be rolling the party van right up to his driveway. :D
Are you holding an amateur-radio-license?
Is it O.K./legal, do do something, that radiated on 1MHz ?
In the EU it is not!
Take care of yourself!
73 de Markus ; db9pz
I think you can transmit anything under 100mw
@@alexandrsoldiernetizen162 "I think" ... famous last words, hmm?:))) (Video 13:51)
An example: Europe-wide free: 863 - 865 MHz with a limitation of the transmission power to a maximum of 10mW. (This is regulation Vfg. 107/2018, limited to 2028).
For you to think about: Remember the frequency auctions from time to time, all over the media? The national states watch over their frequency sovereignty like a lion mother, because this is simply the infrastructure and also a huge income factor. Lets have a look at Germany, matching the topic below 30MHz:
- Transmission of time signals for radio clocks (DCF77)
- Uses of the BOS and military users
- Communication between embassies and home countries
- Communication with research stations on other continents
- Transmission of data with radio messages to one or more receivers for switching and control actions (radio ripple controls)
- Communication in support of humanitarian assistance in the event of a disaster
Oh boy, are you in trouble if you turn on your amateur-protect (with all its harmonics and interference frequencies). This is no game, but deadly serious, at least punishable by large fines up to imprisonment. And if it is not as terrible as I described, even a 1mW "pirate-station" can annoy and make the life of your neighbors worse. And "it is just that one time" is no excuse. Think about that everyone acts this way ... and why build something like that? Wouldn't this be a remote control ... for permanent use?
BTW 526,5 - 1606,5 kHz is reserved for Sound broadcasting (TK). So 1MHz? Have fun with the authorities!:)
amateur-radio: 472 - 479 kHz Amateurfunkdienst D80A, 1810 - 1850 kHz AMATEURFUNKDIENST, 1850 - 1890 kHz Amateurfunkdienst D96, 1890 - 2000 kHz Amateurfunkdienst D96, 3500 - 3800 kHz AMATEURFUNKDIENST. 7000 - 7100 kHz AMATEURFUNKDIENST. 7000 - 7100 kHz AMATEURFUNKDIENST ÜBER SATELLITEN, 7100 - 7200 kHz AMATEURFUNKDIENST, 10100 - 10150 kHz Amateurfunkdienst, 14000 - 14250 kHz AMATEURFUNKDIENST, etc. (Video 14:13)
The topic cannot be grasped in a lifetime and is very interesting. Markus mentioned an amateur radio license. I think this is a good suggestion if you are interested in the topic! It's a very exciting and nice hobby:)
sources: mentioned EU paper, "Frequenzplan Deutschland", Bundesnetzagentur.
Edit: Of course you have to look that up for your country, ask an local expert or your competent authority. Countries with wide areas and areas with low population density may have a relaxed view on the topic. I just don't want anyone to pay a fine that is 100 times more than the craft/research project. They never accept a "I didn't know that ...".
Incidentally, I doubt that the transmission system shown in the video exceeds an effective transmission power of a milliwatt (And yes: He even calculates his power amplifier stage having 15 MICRO Watts, see 9:56 ). Your 100mW ballpark-number in contrast is still very hefty for some frequency-areas and applications!:)))
Markus: We've seen a car radio tuned in to the "test-project-frequency" and very American looking mailboxes. So ... I (and with the warning at 13:51 ) bet that this is/was illegal. FCC: Hold my beer! Hehehe
@@dieSpinnt lol! You apparently have never run a spectrum analyzer this side of the pond. You get like hundreds of times more spurious radio emissions from dying power transformers, bad wiring, dying motors, hair dryers full of burnt hair, any number of brushed motor appliances, and other crazy things. So not too many are worried about someone playing around with homebuilt AM transmitter experiments out of some 40 year old Forrest Mims book, or an old Boyscout handbook from the 1900s. :D Mainly because its getting drowned out by all the other noise, like a 2 cycle scooter with no muffler operating next to a bunch of jet planes about to take off. lol! Not to mention solar radiation in the daytime as well. But do the same thing in the dead of the night, 300 yards away from some longwave low power radio DX chaser, yeah, that guy might gripe to the FCC, just because they have nothing to do. On the other hand, if you run your TIG welder in the dead of night, and it throws out some hellish wide band noise RF noise, not a whole hell of a lot that guy can do because its incidental RF noise, not a deliberately made transmitter.
Schematics with to many mistakes
Intended for skilled people
Not good , sorry .
Your poor neighbors 😂😂
lol qrp on the commercial AM broadcast band, would be interesting to try sending code at 1700 KHZ to see what you get in return lol. but like you said, you have to be a bit careful not to qrm over top of another station that might be occupying the frequency you wish to use.