Instructables
I have, for some unknown reason, always been interested in ancient technology, mainly electronics and mechanical things and I have always wanted to make a true old fashioned style crystal radio. A crystal radio, or crystal set as it is sometimes called, is a radio that only uses the power of the radio waves picked up by the antenna to generate the sound heard in the head phones. The reason it is called a crystal set is because they use a mineral crystal as a diode for the detector in the circuit.

Quite a few years ago I found a book in the library called "Radios That Work for Free" by K E Edwards and found a set of plans for a radio that I just had to make, unfortunately I did not have the resources to build it at the time so I made a photo copy of the pages from the book for future reference. Well I was poking around on the net the other day and found a site that sells copies of that old book, along with various other electronics books and parts related to crystal radios and decided to order a copy for myself along with two 365 pf variable capacitors needed for the circuit I copied from the book.

The radio that I am going to build is the second one shown in the book but I am going to make some changes to the original set. The three changes I am going to make to the set are that I am going to build the set into a box instead of just having the control panel attached to a base board. I am also going to make an antique style "Cats Whisker" style detector instead of using a Germanium diode and use a matching transformer so I can use a set of modern headphones instead of trying to find an antique high impedance set or a crappy little crystal earplug.

I have written this instructable assuming the reader has basic wood working and electronics skills like making boxes and soldering, explaining the more involved and specific tasks in detail, as in winding the coil.
 
Remove these adsRemove these ads by Signing Up
1-40 of 94Next »
AndrewCampbell11 months ago
Wow, this is really elaborate and dedicated! Personally I am not much of a technical person but I am sure a sucker when it comes to antiques. I always feel that they are so classy and makes me feel that I am able to time travel just my interacting with such antiques. However, I do not think I would be able to accomplish building such timeless radio on my own as it just seems too tough for me. But if I were to make one on my own I would most probably put some antique silver designs on it just to add on that vintage feel.
maximzodal1 year ago
Outstanding! I will certainly use a lot of the information here when I build mine.
kynite1 year ago
what's the purpose of the coil in the circuit?
You are very capricious. Congratulations on the project.
i made something like this out of a book but icant decipher any of the things i here! is there any way to make it louder?
Radio Shack sells a small 9v amp you plug into the headphone jack.
Works Real Good.
thanks!
Dr.Bill3 years ago
VERY WELL DONE !
There are schematics to be had for some of the most complicated crystal sets
complete with Wave Traps, Ferite wound coils, 600/44 Litz Wire, and lots of other things !
There is even a DX Contest ! for AM Listening !
I have built several of these sets and the best so far was a Push/Pull wired coil with 2 tunable tank circuits.
Check out midnightscience.com plenty info there.
Also, Crystal Set Society is another good source for AM DX'ing Contest.

Great Ible !
More please !
riverreaper3 years ago
mabey ill just put the scanner in a nice looking box like that one an pretend like when i was a kid :O)
riverreaper3 years ago
does the floor jack hold your table up
riverreaper3 years ago
i wanted to build one but now i think buying might help me live longer lol
Excellent job, but how can you use low-impedance earphones with this set?
uptight4 years ago
carrier wave amplitude modulated draw creates an optical illusion!!!
Xellers4 years ago
Dual 1T4 regenerative vacuum tube radio receiver =P

The first tube is an RF amplifier, while the second serve as the regenerative stage.
DSCN1516.JPG
Normjr5 years ago
This has to be, so far, bar none, absolutely, positively, THE BEST Instructable that I have EVER been to. It is also the most professionally documented. The photographs are crisp and clear and are provided not only at the most important steps, but also many of the intermediate steps. The instructions are easily understood, easy to read, with proper grammar and correct spelling. It, in nautical terminology, “Blows all of those mint box instructables clear out of the water and sends them all to Davy Jones' Locker”. Ohm you certainly have done one “bang-up” job, you are the only instructor that I have subscribe to. This Instructable, in my not so humble opinion, deserves the “Grand prize of Grand Prizes award” if there is one.
Ohm (author)  Normjr5 years ago
Well, thank you very much :) I did get second place in the science fair contest, the winner did a very cool Rubin's tube.
zoltzerino5 years ago
Ive been looking into this and i can get all the parts instantly except ceramic headphones (are these necessarily?) because if they are not ill just use a normal pair. ZZZZ
Ohm (author)  zoltzerino5 years ago
No for a crystal radio you have to use high impedance headphones or as it mentions in the instructable, you have to use an impedance matching transformer to run normal low impedance headphones. You could also use a crystal ear phone which is high impedance as well.
zoltzerino Ohm5 years ago
Well to give me an idea on how to gauge it is 8 ohms high or low impedance? ZZZZ
Not sure if anyone has responded to you, but 8 ohms is very low impedance, high impedance runs 1k+ and if you get into serious xtal set building a 1k to 8 ohm transformers does not match a high Q tank circuit load very well. You need more of a 40K + ohm transformer to match that to 8 ohms but for this circuit using magnet wire and an air core 1k to 8 ohm that radio shack sells should be perfect. That is what I used.
StopPre5 years ago
Hey Ohm, what book is that? sounds interesting. :)
Xellers5 years ago
I finally got around to building a radio! For years, I knew how to build one, but didn't because I live in the city, and putting up a 100 foot antenna simply wouldn't be possible. But then, an idea came to mind. What if I made the coil big, REALLY BIG and had it serve a double purpose? So I took some pieces of wood about a yard and a half long and nailed them together to make the form. Then, I wound all of the stranded wire I had in my house around the form, and my coil was born. Unfortunately, I didn't have any variable capacitors or high Z (Impedance) earpieces, so quickly soldiered together a five minute transistor amplifier (Not push-pull or anything fancy, just a single transistor with a bunch of resistors), and for the headphones I used an old '60s telephone headset. Instead of the variable capacitor, I used a fixed 470pf ceramic disk one that I found lazing around in my parts box. Excited to put it all together, the whole project took about an hour and a half from idea on paper to working device. I'm pretty proud of my creation. I'll be sure to post some pictures soon...
Xellers Xellers5 years ago
I just built my second radio! I found an LM386 and cobbled together a short antenna, a loopstick from an old TV, and a rectifier diode for the demodulator (detector) and a small capacitor and connected it to an 8 ohm speaker. It sounds great! Pictures coming soon. I am currently working on a Tube Regen using 12dz6 pentodes. I promise I will write more.
LM386, isn't that an operational amplifier DIL IC? ZZZZ
Xellers Xellers5 years ago
I just finished the regen! Works great! Instructable soon. I also built a two tube IT4 radio. I also put up a 100ft antenna and made a 5 minute crystal set.
mattccc5 years ago
i have that book the the boy electrician
alexhalford5 years ago
If you need to wind a coil quickly, stick the form into a lathe and just guide the wire along (wear gloves). Makes it really quick and (worryingly) quite fun. Great 'ible. AlexHalford
Ohm (author)  alexhalford5 years ago
That works but it helps to have a way to count the winds, for that I use a micro switch attached to an old calculator with the switch soldered in place of the + button. I enter a 1 and turn it once by hand and it counts from there. Unfortunately with this particular coil being that it has so many taps you kinda have to wind it by hand.
alexhalford Ohm5 years ago
Love the idea with the calculator. Also, you could time yourself with a stopwatch and compare that to the speed of the lathe (i tend to use 65 RPM for coil winding) to figure out how many you've done. AlexHalford
scooter7506 years ago
I used plexiglas for a reproduction radio panel once, but sprayed the back of the panel black. This made the front finish very smooth and shiny black, but scratch-proof - more like bakelite. I used white letters on black labelling tape for the control lettering.
Ohm (author)  scooter7506 years ago
Yeah I realized that I should have done it that way after I had already painted the front of the panel. Oh well I well remember that next time.
Dencohe6 years ago
(removed by author or community request)
Ohm (author)  Dencohe6 years ago
It shouldn't make too much of a difference, I can't find my book right now with the calculations for the coil but it should be OK. Also since the coil is tapped your breaking up the coil into smaller coils with the taps and strong stations tend to be tune in on several of the taps.
Dencohe Ohm6 years ago
(removed by author or community request)
Ohm (author)  Dencohe6 years ago
You well need to post some photos when it is done, I can't wait :D Are you building it into a box like I did or are you just mounting the panel to a base board?
Dencohe Ohm6 years ago
(removed by author or community request)
Ohm (author)  Dencohe6 years ago
Why did you order a rotary switch from Bangkok? There are so many suppliers that would be more local, even if you had to order it over the internet? I can get them locally for $2. Should look cool mounted breadboard style like that and the original set that was shown in the book was just a panel mounted to a base board.
Dencohe Ohm6 years ago
(removed by author or community request)
Dencohe Dencohe6 years ago
Hey Ohm here it is, All done and everything working like you said, its the best set ive ever made. It has a kinda modern future theme. Hope you like it. Not so good at soldering but was able to do everything
IMG_0109.JPGIMG_0110.JPG
Very nice work from both of you !! I have made several dozen sets none as fancy as these .....started back in the mid 60's when AM was still king and you couldn't touch the dial and not hit another station ......now I get 3 stations a local Christen station ESPN and a Spanish station ......I have tried changing antennas and different crystals Galina fools gold store bought and still 3 .....I may take a crack at making this one ....keep up the fine work
1-40 of 94Next »