Surfing around the net I ran across a site that mentioned the old, original radio sets. We called them crystal sets and they were old in the 50's when I was a kid. In case you don't know, a crystal radio gets it's only power from the radio station in the form of radio waves. No batteries, really off-grid! I remember what fun it was to sit up after dark listening for faraway stations and logging them in the "DX" -ing book. Seems like a good thing to do now when I can't sleep or whatever so I'm building a radio "from scratch" like the one I had in '56. A few parts I salvaged from a dead transistor radio, a couple I got at radio shack and one is coming in the mail. Very soon I will be 12 years old again, LOL. Talk about yer 2nd childhood. Worst part so far has been eating all that oatmeal. If you don't remember an oatmeal box was the perfect diameter to wind the coil on. Well I'll give a progress report soon, when it's up and running!
Yesterday I got the plug soldered on to the earplug cord, then found out the receptacle you plug it in to is the wrong kind, back to the Radio Shack, dern. I want to make the very simplest kind of radio but keep running into various "improvements", little changes or additions that are supposed to make it better. Guess I should quit reading and wait for my wire to come in.
OK, the wire and stuff is here. I emptied the oatmeal box. This is the big box, 5 inches in diameter. I am sure we used the smaller one as a kid but the directions I have are for the large. After I get it working I will cut off some of the extra cardboard. Wound the coil last night, about 3/4 of the box can be cut off later. It's just 40 turns of #24 ga plastic insulated wire with a small loop twisted every 5 turns for a tap. I'll remove the cover from the taps and take a picture later. ETA: I sanded a spot on a copper cold water pipe and put on a hose clamp so I will have a shiny spot to attach the ground wire to. Must have a good ground connection as well as an antenna.
Last Edit: Dec 16, 2012 6:28:01 GMT -6 by mogarden
Radio reception is poor since I live in a basement apartment. One cell phone I have gets no bars unless I go outside, the other get 1-2 bars sometimes. So I should not have been surprised to get naught but static on the first attempt. My antenna was also short, the "ideal" is 100 ft they say. That won't happen, lol. I do have a spot outside where I will be close to a water faucet for the ground connection and I can string up a temporary antenna wire for the next session. All's I hafta do now is wait for a nice day in December.... ;D
Finally got a picture but the parts are barely visible. One crystal diode, one 47K-ohm resistor, the coil with a tap for every 5 turns(40 turns total) and the high impedance earplug. The diode and resistor are clipped in place so I can change the part if needed. I have a link to a site with a more clear drawing. Also found a plan for a "spider web" antenna that is supposed to work better inside, plus be more portable than the long-wire version. Still has to be grounded but that's OK. My main reason for building this set is to make a list of all the stations I can pick up, (mostly at night). Reception is better at night, something to do with the ionosphere.
Last Edit: Dec 19, 2012 3:51:57 GMT -6 by mogarden
I have cut the coil box down to just under 4 inches, hoping to find a wood box 8x10x4 to put it in. One jumper is still on, going from the crystal diode to the coil taps. That is the reason for getting only 2 stations, I'm sure. Each tap will let in stations within that range. In this case one high and one low. So...I have found a schematic that adds a variable capacitor parallel to the coil to allow tuning a tiny bit at a time.
Well I found a wood box at the Goodwill of all places. It will hold the coil and etc. Happened to have a piece of pick guard material left over, it's black plastic 1/8 inch thick. I will use that for the front since it's thin and not magnetic and I can drill holes easily. I started making a frame for a compact indoor antenna that will sit on top. Need to find brass escutcheon pins for the wire net, back to Lowes...
Long-range night time reception especially in the short waves is better on cold clear nights. By the time I've filled in a couple pages of far-off stations, I'll get bored with it and be getting ready to do a little garden work anyways. I have to re-mix all the dirt in my containers, get the old roots out, etc. Sounds like a short task but everything takes me longer now. I ain't decided for sure which tomatoes I'll start yet, better get busy studying on that before long. Can y'all believe January is half over?
Post by cottonpicker on Jan 21, 2013 10:50:04 GMT -6
I BUILT SIMPLE, EARLY-TYPE CRYSTAL RADIOS BACK AROUND 1952. THEY USED A GALENA MINERAL AND ''CATWHISKER'' ( ACTUALLY, A VERY THIN WIRE ) ....BEFORE DIODES REPLACED THE COMBINATION. I COULD PICK AROUND ON THE GALENA MINERAL---THE REAL CRYSTAL-- WITH THE CATWHISKER WIRE UNTIL A STATION CAME CLEARLY INTO RANGE. I SEEM TO REMEMBER THAT I ORDERED THE KIT FROM EDMUND SCIENTIFIC IN NJ. FOR A MORE ACCURATE DESCRIPTION OF THIS TYPE OF CRYSTAL SET AND HOW IT WORKS, TRY GOOGLING IT. THIS THREAD BRINGS BACK A FLOOD OF CHILDHOOD MEMORIES...
ANTENNAS--- ONCE TRIED STRINGING A WIRE ANTENNA ACROSS OUR BACKYARD WHICH WAS ONLY ABOUT 100 FEET WIDE. BUT, IT ONLY GATHERED ENOUGH POWER TO BRING IN OUR LOCAL RADIO STATION ( KASA, 1210 AM, ELK CITY, OK ). IT WAS A MUTUAL RADIO CORP. STATION AND CARRIED MOST OF MY AFTER- SCHOOL RADIO PROGRAMS. THAT ANTENNA LASTED UNTIL DAD CAME IN THRU THE BACKYARD ONE NIGHT AND HUNG HIS NECK ON MY ANTENNA....TORE THE WHOLE THING DOWN. IN ORDER TO LISTEN TO FARTHER DISTANT STATIONS REQUIRED A MUCH LONGER ANTENNA SO I HOOKED INTO THE METAL CYCLONE FENCE AROUND OUR YARD OR INTO A BARBED WIRE FENCE WHICH WAS MUCH, MUCH LONGER AND, THUS, BROUGHT IN A STRONGER SIGNAL. GUESS THAT WAS MY FIRST ATTEMPT AT EXPERIMENTATION WHICH, YEARS LATER, BLOOMED INTO A SCIENTIFIC CAREER THAT LASTED 40 YEARS.... IN CHEMISTRY, NOT RADIO. COTTONPICKER
The commercial diodes like I used are actually just a tiny crystal and a whisker, all frozen and sealed in glass. You can see it all thru a hand lens, but that whisker can't move. That's what I like about it. The germanium diodes like 1N34 are about the most popular. Silicon diodes need too high of a voltage to get started. If you do want to google something interesting, look for "foxhole radio". They used a rusty razor blade and a lead pencil. That's primitive!
So....I made a type of antenna that's supposed to be better for indoor use. It's a long wire but wrapped around and around instead of strung out straight. Good thing I didn't make the box I had thought about, to use as a base since it's top-heavy. I still need to turn off all CFL's and flor lights as well as computer, too noisy. I may have to wait for spring to do any further testing, outside. If I'm still able by then, my energy will go more towards the container garden I'm sure. Here's a pic of just the antenna. I'ts 1 foot wide.
Post by Pharmer Phil on Feb 1, 2013 7:37:57 GMT -6
Nice Mo, looks like some tedious work there stinging that together.. I was wondering if them cfl's caused any type of interference..since adding three to the kitchen..I notice one of my remote thermometers isn't working...
The CFL's even interfere with a reg AM reddio that I use for power outages, don't bother FM. ETA: If you're wondering, one of my emergency lights is batt-powered CFL. The other is LED and not as bright but no noise.