Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Wed 20, 2021 11:57 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 118 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6  Next
Author Message
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 4:09 am 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 704
Location: Colorado Springs, CO 80917
Quote:
not sure how good a detector a Transistor junction would make


That's why I offered to try reproducing his setup with a transistor. I suspect, however, that it works as well as the average junction diode but perhaps not quite as well as a hand selected point contact diode (though some of the early transistors were point contact construction, too).
I have another suspicion that his setup is not tunable anywhere near the broadcast band. I encouraged trying an untuned setup: just coil, diode, earphone (+ perhaps a resistor if it's a modern ceramic piezo earphone). Never heard whether he tried that or not. Seems to be having fun tinkering versus chasing a single design until it works.


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 4:37 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 39261
Location: SoCal, 91387
hwhall wrote:
I encouraged trying an untuned setup: just coil, diode, earphone (+ perhaps a resistor if it's a modern ceramic piezo earphone).

Actually all he needs is a Diode, and an earphone, connected to an antenna and ground. My first radio was a potted Galena crystal and Cat's whisker connected to just an antenna, and I could get a nearby 50 kilowatt flamethrower, and sometimes a slightly more distant and lower powered station.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 5:25 am 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 704
Location: Colorado Springs, CO 80917
Quote:
Actually all he needs is a Diode, and an earphone, connected to an antenna and ground...I could get a nearby 50 kilowatt flamethrower


We don't know if he has a convenient blowtorch like that nearby. He knows at this point that the earphone will make noise. But the rest is uncertain. If he proceeds with the ferrite antenna correctly, his tuning cap will probably get him part of the AM band & not need a good ground or lots of antenna hanging outside.


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 1:04 pm 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
you are correct I was trying to use the parts I had and make a cheap crystal set that I could have fun building and enjoy. but you guys are the experts here if you guys say I need a diode then a diode I shall get.
Wayne- I did try your untuned setup it is still wired up in my barn, that's what I am going to post pictures of it later today. I don't mind the anntena and ground hanging everywhere but its just one more thing to pick up and trip over.
Richard & peter- Richard I think my strongest station is 30 miles away at 15,000 watts, not a blowtorch like yours but still enough. I think your first radio was similar to what peter posted minus the ground and antenna. it looks pretty simple. I know that there is no diode on the board you sent me however I am sure there's one on my GE I will continue to look.
today I will post pictures of my current setup and will keep tinkering.
thanks,
henry


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 4:35 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 16881
Location: S. Dartmouth MA 02748-1225 USA
whfh99 wrote:
...Chas- thanks for posting the diagram I will be looking around tomorrow for a good ground. What would I use as my antenna wire? Just standard wire right? -henry
Yes, you can use almost any wire that can stay up... Meaning, the longer the length suspended, the more tension on that length of wire until it breaks.

The most "correct" for a home radio installation is a 14 ga hard drawn copper strand wire. This is the wire type that was put up in the many antenna kits offered since the early 20's. An important fact is that soldering will weaken hard drawn wire. So, it is important to use bronze clamps to make electrical mechanical connections.

It is possible to use what ever wire laying about, galvanized steel wire from fencing. Electric fence wire for example.
Initially, any wire that can rust/corrode will work for a while until such oxidation takes place then the antenna can make noises.

Because erecting any antenna is, well a nuisance at best, returning to make repairs time and time again is impractical. Choosing a strong combination of materials with good installation practices will have an antenna stay up for many years and be useful for different radios in the future. Same is true for the earth ground... chas

_________________
List' & I will Enchant Thine Ear


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 8:32 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4956
Location: Texas
I recall my earlier observation that a crystal radio is a system of different functions and that the signal is only as strong as the weakest link. Then I recall corresponding with Ben Tongue when I was helping him test his crystal radio "in the field." He told me that his antenna was a wire in the attic. Admittedly, he was in an urban area where AM stations abounded.

The point is, making a good antenna is not rocket science. Follow the axiom "longer, thicker, higher" and it gets progressively better.


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 9:26 pm 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
well, I took pictures of my setup today and I will look for pipes in my basement later for a ground. however, now that I know that I need a better ground and antenna should I still post my pictures?
I also found some electric fence wire that I think I can use hung from a tree.
-henry


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Wed 21, 2021 11:15 pm 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 704
Location: Colorado Springs, CO 80917
Quote:
now that I know that I need a better ground and antenna should I still post my pictures?


Yes, please. I'd like to see what you've assembled & hear whether you get any results at all with that.
--Wayne


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 12:01 am 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
I don't think you understand I meant the radio setup with the incorrect ground and antenna, I have not built the one with the right ground & antenna but once I have I will post pictures.
I was looking around in my basement for cold water pipes that go into the ground and found a couple but they all go down deep into the earth, too far to dig. I think I have asked this question before but could someone tell me a list of options that could work as a ground that might be easier to reach? I already am going to use thick electric fence wire as my antenna.
again thanks a lot for your help!
-henry


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 12:14 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 6274
Location: Beautiful Downtown Burbank CA
whfh99 wrote:
I was looking around in my basement for cold water pipes that go into the ground and found a couple but they all go down deep into the earth, too far to dig.

You don't need to dig. Connect your ground to ANY cold water pipe. They all connect together somewhere. :roll:


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 12:17 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 39261
Location: SoCal, 91387
Henry, I would suggest constructing the simple receiver and trying it with just an antenna, to begin with. If you can get a station, then experiment with different ground connections to see if you can improve signal strength.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 12:21 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 16881
Location: S. Dartmouth MA 02748-1225 USA
Quote:
I was looking around in my basement for cold water pipes that go into the ground and found a couple but they all go down deep into the earth,
Any one of those is fine. Choose the one that is closest to where you want to test/use the crystal radio. If the copper/iron pipe that goes into the earth runs under that location then connection at the point is fine. Clean the pipe of rust or tarnish carefully and use a bronze ground clamp from a electrical supply store. No bronze clamp? Get a stainless gear clamp like used on a auto radiator hose. pinch the clean copper wire under the clamp and tighten... Clamp is too small, get two and join them end to end to make a larger clamp...

_________________
List' & I will Enchant Thine Ear


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 12:55 am 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
I think I will take Richards suggestion and I will experiment with grounds after the circuits built. I do have clamps I can use with the pipes as well.
-henry


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 5:09 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4956
Location: Texas
Don't forget that trees are also at ground potential. They have some insulation capabilities but it's really better if you suspend your wire from the tree with something that insulates it from the tree branches. Trees are even more grounded when they're wet. So if you're using bare wire for the antenna, hang it with fishing line or some other plastic line or even use some sort of insulator like a prescription bottle or a plastic bottle cap you've drilled holes in.

Given the distance from the stations and the signal strength they emit, I'm still going to advocate that you start with a good ground along with a good antenna. That way you're eliminating all the weak links you can.


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 5:15 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 39261
Location: SoCal, 91387
PVC insulator between suspension cable on the right and antenna wire on the left. Done at both ends, so the antenna wire is "floating" electrically, with just a lead in wire attached.


Attachments:
outside antenna suspension coupler.JPG
outside antenna suspension coupler.JPG [ 52.98 KiB | Viewed 1181 times ]

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////
Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Thu 22, 2021 8:37 pm 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
I found a good copper pipe ground in my basement I can use, and I used sandpaper to take off the tarnish. next, I am going to put together my antenna, then I will complete the circuit.
stay tuned.
-henry


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Fri 23, 2021 10:26 pm 
Member
User avatar

Joined: Mar Thu 04, 2021 2:18 am
Posts: 523
Location: New Hampshire
***Deleted****


Attachments:
IMG_2225.JPG
IMG_2225.JPG [ 595.01 KiB | Viewed 1118 times ]
IMG_2226.JPG
IMG_2226.JPG [ 634.18 KiB | Viewed 1118 times ]
IMG_2227.JPG
IMG_2227.JPG [ 694.86 KiB | Viewed 1118 times ]
IMG_2228.JPG
IMG_2228.JPG [ 559.98 KiB | Viewed 1118 times ]
IMG_2229.JPG
IMG_2229.JPG [ 876.17 KiB | Viewed 1118 times ]


Last edited by whfh99 on Sep Thu 02, 2021 12:46 am, edited 1 time in total.
Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Sat 24, 2021 12:39 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 16881
Location: S. Dartmouth MA 02748-1225 USA
Henry, Can you find where the cold water supply enters the basement? That should be a copper or iron pipe. If it is plastic then there is no effective ground using the water system. Follow the pipe if it is metal to where you are connected. Any intermediate point that the metal is broken by a plastic pipe then there is no ground.

_________________
List' & I will Enchant Thine Ear


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Sat 24, 2021 4:21 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4956
Location: Texas
How long is your antenna? Where is it located, and how high up?


Top
 Profile  
 
 Post subject: Re: First time crystal radio build
PostPosted: Apr Sat 24, 2021 5:08 am 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 704
Location: Colorado Springs, CO 80917
Is that last picture the antenna wire? It looks awfully short. Like a foot or two? You want more than that, I'm pretty sure.

The coil shown (I'm guessing ~2 in dia, ~6 in length, ~100 turns) is on the order of 100-200 uH. I think that's ~1Kohm reactance at midband. If you had 100 uW into that coil from the antenna, about 0.3V will develop across the coil. That's just at the edge of germanium froward voltage drop & well below that for silicon. However, the earphone is making noise, so at seems some RF noise source is getting rectified in the transistor junction. It may not be getting enough desired AM band RF into the setup to be heard.

One other thing: when it comes time to add the tuning capacitor to the setup, I'm going to say that the coil might need some adjustment/refinement. If my guesses were right & it's near 150 uH now, and the little polyvaricon-like capacitor he has can get up to 150 pF, it may tune the upper end of the AM band (& higher out of band). I think something like 400 - 500 uH would be better.


Top
 Profile  
 
Post New Topic Post Reply  [ 118 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  


































Privacy Policy :: Powered by phpBB