AM receiver

[blueroomelectronics]

CHUM radio was about 20 miles from the house, no problem. My crystal set wasn't a pretty as this one though.
**broken link removed**

 

[Gaston]

when i was a kid i never understood how a cyrstal radio worked because i thought the crystal worked like the crystal ocillator in a cb radio. i didn't know it was to make a diode

 

[RadioRon]

When I was a kid, I was given a "ROCKET RADIO". It was a lot of fun.

Looked like the center one in this picture:
https://www.crystalradio.net/misc/rocket/index.shtml

 

[Gaston]

whats a rocket radio? my uncle gave me a simple kit from radio shack. it was a piece of cardboard witht the components drawn on it and springs sticking up that you wedged wire into the coils to make contact to conect the pieces. it had an earplug
for the speaker.

 

[blueroomelectronics]

Mine looked more like this
**broken link removed**

 

[Gaston]

mine was very similar to that. if i grounded it through the receptical in the house i could actually pick up a station

 

[mvs sarma]

I remember a crystal Radio ( which I realised after my degree in science) in (1954),at my 9th year of age. Defence personel has installed for short wave and we were also allowed to listen to Radio Srilanka from a distance of one thousand Miles. Perhaps he must be using some High impedance headphones.

 

[blueroomelectronics]

I found my heat register vent made a good ground, a long wire out my bedroom window made a great antenna.

 

[mvs sarma]

I found my heat register vent made a good ground, a long wire out my bedroom window made a great antenna.

Yes Bill, Many times it would be a issue with good earth to the Receiver.The effectiveness depends more on that. Off late it is a problem finding Germanium diodes like OA79 or 1N34A. Perhaps we have to salvage from old scrap and use. I only wonder whether schottky diode could be used instead?

 

[Hero999]

I got excellant results from my crystal radio when I used the outer screen of the TV aerial's coaxial cable as an aerial and the radiator as an earth connection.

 

[blueroomelectronics]

Yes Bill, Many times it would be a issue with good earth to the Receiver.The effectiveness depends more on that. Off late it is a problem finding Germanium diodes like OA79 or 1N34A. Perhaps we have to salvage from old scrap and use. I only wonder whether schottky diode could be used instead?

It's still possible to find the 1N34A in stores around Toronto. Not sure if a schottky diode would work, it was decades ago when I built my crystal set and it came with a 1N34A

 

[Hero999]

Germainium diodes can easilly be replaced by small Schottky rectifiers which do a better job.

 

[Roff]

It's still possible to find the 1N34A in stores around Toronto. Not sure if a schottky diode would work, it was decades ago when I built my crystal set and it came with a 1N34A

Wimp!
My first one used a little chunk of galena, imbedded in lead(?), with a "catwhisker" that I had to move around to find a sensitive spot.

 

[Gaston]

what do you think the voltage drop was for a crystal and cat wisker? more or less than a germanium diode? and what about a rusty razorblade and wisker?

 

[mvs sarma]

Wimp!
My first one used a little chunk of galena, imbedded in lead(?), with a "catwhisker" that I had to move around to find a sensitive spot.

Yes Roff,
I remember Gillette blades used as detectors. they have a similar coating in those days.

Thanks to Hero999.

 

[blueroomelectronics]

Wimp!
My first one used a little chunk of galena, imbedded in lead(?), with a "catwhisker" that I had to move around to find a sensitive spot.

That was high tech, I just wanted to listen to music when my parents thought I was sleeping. Moving the whisker around under the blankets might have looks suspicious.

 

[mvs sarma]

what do you think the voltage drop was for a crystal and cat wisker? more or less than a germanium diode? and what about a rusty razorblade and wisker?

It will be more than Germanium diode and also inconsistent.

 

[Roff]

what do you think the voltage drop was for a crystal and cat wisker? more or less than a germanium diode? and what about a rusty razorblade and wisker?

I think you can use a lot of different materials, so long as the contacting surfaces have a lonlinear V-I curve. I once detected a local radio station with a contraption that consisted of two pieces of a tin can (plated steel, actually) bent into L shapes and nailed to a board, with a piece of fine wire laid across them, as in the drawing below. Needless to say, it was highly microphonic, which was probably what I was actually trying to achieve. I remember I had it connected to some long wires that went to a friend's house. We were trying to get some sort of intercom going. The wires acted as an antenna, and the oxide on the wire/tin as the detector. The result was quite a surprise, as you can imagine.

 

[RadioRon]

Wimp!
My first one used a little chunk of galena, imbedded in lead(?), with a "catwhisker" that I had to move around to find a sensitive spot.

That's nothing. When I was 10 years old my family was camping and for fun I decided to try driving the family car around the campsite (without permission of course). Well I backed it into a tent pole that my dad had secured with a long piece of steel wire. Then I pulled forward and banged into the neighbor's trailer. For some reason the tent pole, with wire attached, had got wedged into the rear bumper and dragged along, and with the same luck, the sheet metal on the neighbor's Airstream had made an unholy union with the rusty bit of fender up at the front of the car. As the adults ran up to the site of the carnage, they stopped in their tracks as they clearly hear "Moon River" emanating from the aluminum wall of that Airstream.

When I finally recovered from my punishment, I had acquired a new and perhaps twisted interest in the magic of radio.

 

[Roff]

That's nothing. When I was 10 years old my family was camping and for fun I decided to try driving the family car around the campsite (without permission of course). Well I backed it into a tent pole that my dad had secured with a long piece of steel wire. Then I pulled forward and banged into the neighbor's trailer. For some reason the tent pole, with wire attached, had got wedged into the rear bumper and dragged along, and with the same luck, the sheet metal on the neighbor's Airstream had made an unholy union with the rusty bit of fender up at the front of the car. As the adults ran up to the site of the carnage, they stopped in their tracks as they clearly hear "Moon River" emanating from the aluminum wall of that Airstream.

When I finally recovered from my punishment, I had acquired a new and perhaps twisted interest in the magic of radio.

**broken link removed**