Introduction: Make a Simple AM Transmitter

Make a simple AM transmitter that will cost you less than $5.

Step 1: Stuff You Need

A crystal whos frequency is between .9000 and 1.2000 MHz.
Some wire
A male headphone jack
A breadboard or experimental circuit board (optional)

Step 2: Wire It Up

The crystal should have a little black dot on it. This is the only pin that we will not use on the crystal. We will connect the red wire of the headphone jack to the pin above the black dot. The white wire can also connect here if it is a stereo jack. We will connect the black wire or the ground to the pin to the right of the dot.

Step 3: Connect an Antenna to It

Connect the last pin (the pin opposite of the dot) to an antenna. I used a really long telephone wire for my antenna (25 feet or so). I got it to play through my whole nieghborhood. Any sort of insulated wire will work for an antenna.

Step 4: Tune Your Radio

You now have to tune your radio to whatever your crystal says. The crystal will show the frequency in MHz and the radio will show it in KHz. If you used a 1.0000MHz crystal then you will tune your radio to 1000. 1.2000MHz crystal will give you 1200 on the radio and so on.

It may take a little time to find your station but it should work.

The louder you turn your music up, the louder it will be on your radio.

-I also found a better version of this. It uses a modulator. This improves the system a ton. Check out the second picture to see this with the modulator.

Comments

author
I AM SETH (author)2016-08-23

How do I use a morse code key instead? Also, where do I put the battery clip without using the modulator?

author
Ashar Husain (author)I AM SETH2017-07-25

you dont need to attach a differet power source as it will take power from the device

author
TuxedoRonny (author)2012-06-27

Hm... I did everything exactly as you stated (without using a modulator) and this didn't work- at all. I have all the exact components, tried several different radios, etc. and still nothing. Are you sure this works on its own? Has anyone else tried this?

author
AlexK293 (author)TuxedoRonny2017-06-20

I tried it too, same thing happened to me. Maybe we should use an amp?

author
simone.mastroianni.04 (author)2017-05-15

Please help me! The crystal has only 2 pins and a frequency of 11.0592 Mhz

(the details are in the photo)

Please is urgent! :(

5807aaea-40b7-4601-99be-47dcbd40b214.jpg
author

Firstly, a 11.0592 Mhz crystal is not in the range described in the Instructable. Second, you'll have to find info yourself (I could not find anything on it).

author

Ok thanks

author
octosloth (author)2015-10-11

omygosh ware in the world do you get that cristal? i've looked evorywhare.

author

You can get 10 pieces for 6 dollars on ebay.

author
bitmaster_1010 (author)2016-10-18

can we use a 555 timer instead of an audio source in radio-wave transmitter?

If yes, then how can i do it?????

author
I AM SETH made it! (author)2016-08-24

I used a HAM radio frequency instead.

image.jpeg
author
stoobers (author)2015-03-26

Have you tested this thing for harmonics?

How would I get rid of harmonics to make the signal cleaner?

Thanks in advance!

author
ChloeS (author)stoobers2016-05-02

Oh it's GOT harmonics, i don't have to build it for that, it's a square wave, odd harmonics everywhere. You fix it by using a lowpass filter, or better use a band pass filter. Basically since this is a crystal and you're not using any tuning mechanism, so it's a single frequency, you just want to pass that single frequency plus any intended deviation (up to maybe 6 kHz) and that's it. If you can't get that specific you want to at least block the harmonics, and subharmonics if there are any.

author
octosloth (author)2015-10-13

i looked everywhere and had to quit because even when i found one it was 24$ for one lousy crystal. i'm glad it worked for you.

author
ChloeS (author)octosloth2016-05-02

mouser.com or amazon should get you a whole bag of the suckers for 5 bucks

author
octosloth (author)2015-10-19

pleease answer: how do you know how much power a ocilator can take?

author
vernkle (author)octosloth2016-04-06

Ebay $0.99

author
pcain1992 (author)2016-02-01

What is the maxim Amperage I can pump into this puppy. I want this little guy to broadcast my morse code message across campus! Possibly a mile radius?

author
vernkle (author)pcain19922016-04-06

I'm not sure, but get the lowest possible frquency.

author
ArI3 (author)2016-03-09

could i replace the jack with a mic?

author
vernkle (author)ArI32016-04-06

Yes, but you will need to build (or buy) a small amplifier.

author
fartnuckles (author)2015-01-22

One thing to note though, Many crystal oscillators have a maximum power supply voltage of 5V +/- 0.5V. Indeed some are only rated to 3.3V max. You will need to check the data sheets for your selected oscillator for it's maximum power supply voltage BEFORE applying 9V as shown. Otherwise they will stop oscillating permanently very quickly if their maximum rated voltge is exceeded!

author
mpetković1 (author)2014-03-07

You have a nice all explained how to make the radio transmitter on the site: https://www.youtube.com/watch?v=_4-Sx-T6VBc

author
gussmith001 (author)2014-01-29

I build this and using an audio output transformer and it works great. Found a 1mhz crystal and audio output transformer on ebay.

author
SelanacScreenPrintR (author)2013-07-02

Is the Modulator in the Drawing below that looks like a Transformer? How can we purchase one, and what do we look for?

author

The transformer is changing the voltage coming in from the mp3 player so the crystal can be "set off" a little easier. You need to kick it in the pants to get it vibrating.

The "modulation" (the signal) is being generated at the source (the mp3 player) and passed to the circuit so a carrier wave can be added.

If you don't use an mp3 player, but just just a voltage source, you have made a "CW" transmitter (for morse code).

author
bilsat (author)2013-10-12

Where i can find the crystal? I live in europe, and greece specifically. Please i want it to find it offline because i got no money for credit cards and i dont use paypal or anything that pays online.

author
stoobers (author)bilsat2013-11-06

Find a place that takes bitcoin.

author
nodoubtman (author)2012-01-16

what does this circuit does in reality??

thank you! :)
marC:)

author
stoobers (author)nodoubtman2013-11-05

This circuit adds a 1mhz carrier wave to the electrical signal from the audio source.

The whole thing is then plopped onto the antenna and the antenna vibrates with those rf's (radio frequencies).

An AM medium wave radio near by can be tuned to "listen" to the vibrations.

author
Bot1398 (author)nodoubtman2012-01-31

Your username says nodoubtman but look you have a doubt!!! :P

author
almamater (author)Bot13982012-01-31

ahhhh very good!!

author
nodoubtman (author)2011-11-19

I have a crystal of 1.8432 Mhz , is it okay?

thanks!

author
stoobers (author)nodoubtman2013-11-05

1.8432 mhz is in the "shortwave" range.
AM radios are in the "mediumwave" range.
To receive the rf made by this crystal, you need an AM radio that receives in the shortwave range.

author
49percentGood (author)2013-06-03

As long as you tune into the frequency that the crystal is transmitting, yes. Substitute any crystal value with the one listed and the results will work. Tuning the receiver to the same frequency as the transmitter is the only difference.

author
VirtualBoxer (author)2013-02-21

Can a receiver be made in a similar way?

author

Yes & No. A receiver to pick up the signal can be done, but sometimes it's a bit weak. It is much easier to make a receiver to tune into local radio stations. The Instructable that I used by MacDynamo is at... https://www.instructables.com/id/Simple-OP-Amp-radio/

I know you asked for a similar way, but the purpose of the crystal in this Instructable is to transmit at that frequency, the Instructable I linked is how to receive signals, so similar in function, not really. But simple in design and easy to build, absolutely. I hope this helps you. Additionally, there is a ton of videos on YouTube, most notably... http://www.youtube.com/watch?v=4E6uwEiOGsQ&feature=share&list=PLtv36f0AWivbNwZWXflk1OATeJlMk3B-P

There is also a follow up video with a schematic and partslist. (Although I noticed he hooked things up differently and sometimes the parts were different but nonetheless it works.) The simplest radio to use in my opinion would be the old school Crystal Radio or Foxhole Radio. Personally MacDynamo's Instructable is the easiest to follow and has the best results of the ones I tried. Enjoy!

author
eric m (author)2013-04-30

Hate the new layout for instructables. BRING BACK THUMBNAILS. So Stupid!

author
jcox24 (author)2012-11-17

I made a transmitter using an oscillator and an audio transformer, run off EITHER a 9v cell or usb

author
Evo7 (author)2012-10-12

Greattt............stuff in here!!!!

author
electronicz (author)2012-04-12

I have a 1.00 MHz crystal like bmlbytes, how high of a voltage can this crystal withstand?

author
account3r2 (author)2011-12-02

if i make my own transmitters and receivers using a 50 MHz crystal, since the crystal isnt in the FM or AM range, would the FCC rules apply to it?

author
gspeed0689 (author)account3r22012-04-04

That is in the Amateur Radio range, and this circuit does not have enough power to really go far. Low power projects like this aren't enforced by the FCC, it's much like one of those mp3 audio devices that broadcast your mp3 player on a radio station in your car.

If you were to boost the power, you would then be subject to FCC rules.

author
nodoubtman (author)2012-02-15

do you need an audio transformer for this? i have a 600: 600 ohm 1 to 1

Thanks!

author
nodoubtman (author)2011-11-16

what kind of antenna do you use ?

thanks!

author
David97 (author)nodoubtman2012-01-31

Just some wire shold do it.

author
Wesley666 (author)2009-02-08

Also what if I want FM not AM?

author
ReCreate (author)Wesley6662009-02-09

get a 100MHz oscillator ...and tune your radio to 100MHz FM

author
Wesley666 (author)ReCreate2009-02-09

so I would tune a radio to 33.3 FM if I had a 33.33 MHz oscillator. (The only oscillator I have is 33.33 MHz) Also how would you build a receiver for a specific Frequency? (Preferably 33.33 MHz!)

author
ReCreate (author)Wesley6662009-02-09

well first fm is from 87MHz to 108MHz what you have there is close to the range of remote controlled airplanes,49 i suppose you might be able to modify a radio to recive 33MHz (try by turning the little "screws" on the radio's circuit board?) also,since it is not in the am or FM range,you could broadcast it for MILES,ive hear of someone sending morse code from one side of the country to the other at 20something MHz

About This Instructable

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Bio: A current student at the University of Advancing Technology. Currently studying Robotics and Embedded Systems.
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