If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #53
Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638
Some of you my have already heard about this in the IRC so this is for the rest of you. I build a crystal radio using no commercially made radio parts (other then the earphone) just to see if I could do it. I because I don't have a meter that reads capacitance all tuning is done with a variable inductor.
Parts list: Wire spindle 30 awg wire 6 screw terminals Short lengs of 22awg, 14awg and 1/4" copper 3 wood screws A diode made from a razorblade, a paperclip and some pencil lead.
The second picture shows how my variable inductor works.
Registered Member #53
Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638
I have only used id for about 20min, I managaget to get 1 station 740khz pretty clearly. Found 820khz <--overlaps most of the other chanles 680khz 590khz
Has any one else made a radio set like this frome "garbage" parts?
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
Nice!
I remember building a similar thing years ago, that was tuned with a variable inductor also.
The variable inductor was constructed by winding about 100 turns onto a small cardboard tube, and then to vary the inductance a short piece of ferrite rod was glued to a stick, and this slid in and out of the coil former. The whole thing fitted into a tic-tac box, and then I glued it to my bedroom wall
I never constructed my own detector though, I just used a germanium diode. The whole project came out of an electronic experiments book, I'll have to dig it out for memories
Registered Member #10
Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424
Just the thing to help you while away the hours on your boat Sure to make EVR jealous as I don't think his boat had a crystal radio
This was my first electronics kit from the late 60's. Actually mine is long gone but this is the exact same one from eBay and a very sentimental find. I still remember many of the part numbers.
Bored Chemist wrote ...
Are you just relying on "parasitic" inductance?
You mean parasitic capacitance to give an LC resonance don't you?
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
This style of radio is commonly known as a 'foxhole' radio. GIs in WWII would build this circuit from a pencil and a razor blade for the diode, some wire pilfered from a dynamo at the motorpool for the inductor, and a high impedance earphone borrowed from a military radio.
I've seen a couple models that incorporated a homebrew speaker made of magnet wire and the top of a steel rations can.
Very nicely done Nik. The construction looks exceptional.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Crystal Radios
