Variable inductor instead of varible capacitor in FM crystal set

[CDRIVE]

I dont know how you will go with the guitar. I think you'll end up going for a proven model before thats going to work. Good luck though

This statement sounds a lot like a goodbye, Do you think you're going somewhere? Not a chance amigo! Please read back through this thread and find my plea and Steve's reply to me. As per the forum rules as stated by Steve I believe my divorce is now officially recognized.

Congratulations, you are the new me!

Chris

 

[dietermoreno]

Well I'll tell you how it doesn't work after I blue the razor blade in my gas stove.

At least then we can put it to bed after it can be debunked as not working.

but even if it doesn't work, it still works just fine to test if the crystal detector is only passing current in one direction using Audacity to record and looking at the screen to see that there is only one half of the waveform either above or below the zero line.

In that image that I posted, I think I have debunked the so called "amplitude modulation" as mains harmonics. I counted the wave peaks inside the super imposed wave peaks and found that there are about 5 weak peaks every 0.001 seconds, which means there is one wave peaks every 0.0001 seconds, which means there are wave peaks at a frequency of 5,000 Hz.

The super imposed wave has one wave peak every 0.01 seconds divided by 2 approxiamately, which means the super imposed wave peaks are at a frequency of 50 Hz approxiamately.

All that Audacity recorded was mains harmonics, which are also sinusoidal and have waves opposite each other just like radio carrier waves. My approxiamate frequency of 50 Hz was rounding, since obviously the mains frequency in the United States is 60 Hz.

Here is an image of mains harmonics I found on Google images that shows the mains harmonics as waves opposite to each other:

Well so it looks like my crystal detector test is going to be testing rectifing mains harmonics.


Who knows, Audacity might just not be able to handle recording RF so it clipped the recording at 5,000 hz instead of 500 khz.

I guess that a 48khz sample rate probably can't keep up with a 500 khz radio wave.

but still, awfully suspicious that the super imposed waveform is at mains frequency. Its 99.9% chance just mains. Even more suspicious is that when I zoom out it appears that there are two 60 Hz waves that are 90 degrees out of phase with each other. I'm just picking up inductance from the poly phase power line across the street.

 

[Mongrel Shark]

Congratulations, you are the new me!

Chris

Just when I though this thread had hit rock bottom...

Guess I cant escape that easy..


As far as the scope shots goes. I thought it had a 50hz look about it... You can save yourself some time, and go here http://www.falstad.com/interference/, Check both the check boxes, set freq to 50hz (or 60hz if thats what tickles you), and set phase to either 0 or 90. You should do this with the largest sub woofer you have plugged in, and turned up really loud. I think it will take about 30 min of treatment, and any further desire to listen to mains hum will be removed. If that dont work, you could try again, for 35min, while zapping yourself in the eye with a piezo. You may need an assistant for the piezo, Although I get the impression there might be a few people willing to help with that... You could ask Chris if you get stuck

If the treatment is successful, you should develop a healthy psychological aversion to listening mains hum. If that doesn't work, I'm not sure I can help...

 

[dietermoreno]

Hey well who needs to pay for an oscilliscope and wave generator when I can get waves for free from mains hum and I can use Audacity as free oscilliscope.

I think it is still a valid technique of testing if a diode/crystal detector is working as a rectifier. If only half of the mains sinusoidal wave exists, then the diode/crystal detector is working.

I do have an aversion to mains hum. I didn't listen to it that much. I just looked at it on the oscilliscope in Audacity.


Well if I get the magnet wire from a speaker, will that require soldering to open up the basket and other things? If it requires soldering, I should just wait until I buy the magnet wire. I have a completley useless guitar speaker that I use to put my laptop on when I bring my laptop into my music room/ experimentation room. The speaker doesn't work, so it might as well be put to use, but I'm afraid of learning how to solder.

Well that was just a curiosity. but in actuallity, it would be nice to have 2 guitar amp speakers so that the guitar amp could play stereo audio when an audio line is connected into its line level line in, so I think I would like to first try to fix that speaker with some help from these forums.

I guess since speakers are so extremely simple, I might be able to learn how to solder it to fix it with some help from these forums.

Then if I fix the speaker successfully, that would be my first soldering project fixing something to help me build up to fixing my broken amps.


New idea: I get the magnet wire from an old amplified PC speaker at the second hand store for $2 and it also comes with transistors, pots, connection wires, and possibly even capacitors and resistors if it has tone controls. It pretty much comes with everything needed to make a fox hole radio (and more than you need since no transistors are required in the fox hole radio) except the crystal detector, variable capacitor, antenna wire, and hi-Z phones.

For the hi-Z phones, an old analog telephone for a dollar from the second hand store should work fine. I can first use the guitar amp to listen for stations while tuning the fox hole radio, and then I can compare the results to using hi-Z phones (telephone).


I tried recording mains without using a guitar using just a 6 inch long instrument cable, and the waveforms were different. The 60 cylcle mains was in both recordings, but in this recording the 60 cycle mains was not super imposed on top of a higher frequency wave, and the harmonics can be seen as little bumps in the waves that all together make the 60 cycle mains into a saw-tooth curve. So in the last recording, it appears that the higher frequency that the 60 cycle mains was super imposed upon was not mains. In this recording, the 60 cycle mains didn't cancel itself out either. In the previous recording, the waves all canceled each other out except mains was still heard. So I think what might be the case is that actually the guitar is working as an AM antenna and the 60 cycle mains is actually acting like a voltage controlled oscillator that is super imposing 60 cycles on top of the higher frequency radio carrier waves.

Attached is 60 cycle mains not connected to guitar.


I found that recording 60 cycle mains is also a good hearing test! I can decrease the amplitude of the wave in Audacity all the way down until I don't hear it anymore. This is with me listening on $150 headphones with the volume on my audio interface/headphone pre-amp turned all the way up with a 10 foot long cord and I am standing 10 feet away from my laptop so I don't hear the hard disc drive noise as much.

I found that my hearing goes down to -83 db for 60hz. I wonder if I could hear human voice frequencies better. I have been taught in my biology class that humans are best at hearing human voice frequencies, and the full dynamic range of -105 db for humans is only for human voice frequencies.

After I cleaned out my ears with hydrogen peroxide, I found that my hearing went to -86 db for 60hz.

I found that just that 3db boost to my hearing really helps me to hear radio stations better in my radio recording of my guitar on my YouTube channel. I had the volume all the way up, and yikes! I had to turn the volume down to only 10% and with the volume at 10% I heard 3 station identifiers not heard before. I heard a male voice say " 'his is ninenty...[static]". Then I heard a deeper male voice say "This is ... [static]...in 12 hours a system will be....[static]....Coming up soon at the top of the hour. This is ...[static]...seven eighty WBBM". Then I heard a female voice say "...oh, hahaha, ..[static] hey how you doin toni-...[static], lot's more of your favorites comin up, star one ..[static]..five point five. McHenry County's variety."

So I guess cleaning your ears with peroxide is good for listening to crystal sets!

So now I have station identifiers for those 3 stations, in addition to the classical station. Funny thing is that of those 3 station identifiers, 2 out of the 3 are FM!

You know what, the frequency of that classical station is 98.7 MHZ. So the " 'his is ninenty..[static]" is the station identifier of that station. So the 3 stations received on the guitar are 780 khz WBBM, 98.7 MHZ WFMT, and 105.5 MHZ WZSR.


I assume that building a proper crystal set instead of using a guitar will increase the gain by much more than 3 db

 

[Mongrel Shark]

Well if I get the magnet wire from a speaker, will that require soldering to open up the basket and other things? If it requires soldering, I should just wait until I buy the magnet wire. I have a completely useless guitar speaker that I use to put my laptop on when I bring my laptop into my music room/ experimentation room. The speaker doesn't work, so it might as well be put to use, but I'm afraid of learning how to solder.

You wont get good wire from a speaker. Try a transformer.

So I guess cleaning your ears with peroxide is good for listening to crystal sets!

Hopefully that will help you listen in general, but after reading some of your other threads I'm doubtful.

You need to slow down, and learn about what you are doing, before you kill people.


I'm starting to think Steve should ban you to protect us from your stupidity.

 

[dietermoreno]

Okay. So I will get the magnet wire from a transformer instead of a speaker.

What random electrical/electronics junk would be a good thing to look for to have a transformer inside?

Will motors be a good source of magnet wire too? I'm thinking of buying an old blender from the second hand store for $2 since that has a motor in it. Of course that will also have connection wires in it, which I also need.



I had some hit and miss luck trying to find a sensitive spot on my razor blade that would clip mains waves in half. I would only find a sensitive spot for a few seconds and by the time I clicked record on Audacity the sensitive spot would already be lost. When I found a sensitive spot, I would hear the mains waves clipping. I was only able to record the mains waves clipping for a few fractions of a second, and when I looked at the osciloscope I found that if I reverse the leads on the razor blade it reverses the half of the wave that is clipped and I found that best results are achieved by having the leads on the razor blade as far apart as possible.

by the way, I tried with and without pencil graphite, and the "hit and miss luck" only occured when one lead was on top of pencil graphite and nothing happened when no pencil graphite was used. So it appears that pencil graphite is a crucial part of the rectifier as it appears that pencil graphite is a semi conductor.

by the way, I didn't blue the razor blade yet. I'll try blueing the razor blade and see if that achieves better results with and without pencil graphite.

A diagram is attached of what I was doing (not including the pencil grahite).


On the internet I have found conflicting evidence of graphite being a semi conductor. I found some articles that said that graphite is essential in the crystal radio as the semi conductor. I found some articles that said that graphite is a good conductor of electricity in both directions. I found some articles that said that graphite for very short periods of time if nano thinly sliced graphite sheets are used will rectify. I found some articles that said that copper wire is traditionally used as the cat's whisker in the detector, and since graphite conducts electricity so well it is used in place of copper wire in the fox hole radio since GIs didn't have access to a hardware store full of wire while they were lieing in a fox hole but they had pencils.


So most likely I discovered nothing in my little experiment when using graphite, it was simply a worse connection with the graphite than with the cable leads and that bad connection was prone to the vibrations of the air and floor so when I walked it would vibrate and that vibration by pure chance created rectification for a few fractions of a second.

 

[Mongrel Shark]

What random electrical/electronics junk would be a good thing to look for to have a transformer inside?

Pretty much everything. Remember I told you to google stuff.

I had some hit and miss luck trying to find a sensitive spot on my razor blade that would clip mains waves in half.

No one here is interested in helping you listen to mains hum. Learn to follow advice/instructions, or lean elsewhere. You have taken none of my advice, so why should I continue to waste my time?

by the way, I didn't blue the razor blade yet. I'll try blueing the razor blade and see if that achieves better results with and without pencil graphite.

And it wont work until you do. Why would you skip that step? Are you such a genius now, that you can make a radio without help? If so then go do it, and stop wasting our time, and the forums storage space. Dis you even consider what I had told you before? Why do you think the razor needs to be blued? To look cool? are do you think it might actually perform a function?


There is a reason for the pencil (which, as I pointed out before, is not JUST graphite), as there
is a reason for the bluing. You have to have both, or it wont work. Thats why its in the instructions. As tempting as it would be to include steps that do nothing in instructions. Like hold your left nostril with a pair of vice grips, and dance a jig. You never see stuff like that written in instructions. What you find is the minimum requirements for a working project. If your project doesn't work and you deliberately skipped a step. you should find a way to fix your problem before asking for help.

Remember our talk about googling stuff.... I shouldn't have to remind you 6 times in one post.

So most likely I discovered nothing

And your going to continue to do that, until you slow down, and pay attention.

I'm not helping you unless its with problems making the radio set I recommended you make. If you use your guitar, or amps, or anything not in the rimstar video, exactly as it is in the video. I will block you, and not see your posts anymore. I have better things to do with my time. Than wasting it, instructing some one, that wont follow said instructions, but instead does as he wants, with no reason or logic. without even bothering to work out why the instructions said to do something a particular way.


How are you still in school? If I was you teacher I would have expelled you by now.

 

[dietermoreno]

Good thing I didn't take the circuit analysis class, or I probably would have been expelled for being a noob for blowing up every circuit in the classroom in my "experiments".

Okay, well I Googled how to remove wire from a motor so now I don't need to ask you how to do it.

I told you that yesterday I did Google "is graphite a semi conductor" and I received mixed results that led me to experiment to find out for myself and my experiment discovered nothing.

I'm sorry, but I guess I'm just not good at using Google. Last semester when my physics teacher put something on the exam that wasn't in the textbook and I asked him why he did that, he said that learning how to Google is even more important than learning physics.

Yes I do know that the razor blade is supposed to be blued, but I didn't know why so I had to find out, and my findings in my little experiment last night were that the reason it has to be blued is that no rectification will occur if it is not blued.


Tonight I tried Googleling "what does pencil do in crystal radio" instead of "is graphite a semi conductor", and I got what I was looking for. I guess that if you choose too specific of a query Google doesn't work. It turns out that I didn't even know what a diode is, so that's why my query was too specific. It turns out that a point contact diode uses one semi conductor crystal and one thin wire.

Remember when I said that in my experiment last night, if I even walked around the room the pencil lead would move and sometimes this movement would rectify? It turns out that the pencil lead being an unstable mount instead of soldered is intentional. It turns out that no rectification occurs if there is no signal. The rectification needs the electric current to work. The electric charge when it flows through the pencil lead to the crystal, the crystal has properties that will decrease the resistance to a lower resistance than the resistance of the pencil lead (the pencil lead has a small resistance that is higher than the resistance of the crystal) in just the right spot and the intentionally poor connection allows only the path of least resistance to allow charge to pass, only allowing charge to pass in one direction. Charge passes from the higher resistance of the pencil lead poor connection to the lower resistance of the crystal. Therefore, charge will only flow from pencil lead to crystal. Charge will not flow from crystal to pencil. It is important that the connection with the crystal on the other side of the crystal is low resistance wire and is a good connection so that a second rectifying junction is not formed.

To make it crystal clear (pun intended), drawing is attached.