somerset amateur radio club presents
TRANSCRIPT
![Page 1: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/1.jpg)
SOMERSET AMATEUR
RADIO CLUB PRESENTS
![Page 2: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/2.jpg)
A HISTORY OF EARLY
RADIO
![Page 3: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/3.jpg)
BEFORE CELL PHONES..
![Page 4: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/4.jpg)
BEFORE TELEPHONES...
![Page 5: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/5.jpg)
THERE WAS CRYSTAL RADIO
![Page 6: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/6.jpg)
A CRYSTAL RADIO IS NAMED FOR IT’S MOST IMPORTANT COMPONENT - A CRYSTAL DETECTOR, USUALLY MADE FROM
A CRYSTALLINE MINERAL, SUCH AS GALENA. THIS COMPONENT IS NOW CALLED A DIODE.
![Page 7: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/7.jpg)
A CRYSTAL RADIO HAS NO POWER SOURCE - LIKE BATTERIES. IT USES ONLY THE POWER OF THE
RECEIVED SIGNAL TO WORK.
![Page 8: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/8.jpg)
A CRYSTAL RADIOS HAVE MANY DIFFERENT DESIGNS.
![Page 9: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/9.jpg)
CRYSTAL RADIOS BECAME POPULAR DURING THE GREAT DEPRESSION, WHEN MONEY WAS SCARCE.
![Page 10: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/10.jpg)
IN WORLD WAR II, SOLDIERS BUILT “FOXHOLE RADIOS.” THEY WERE MADE OUT OF A RAZOR AND
A PENCIL POINT.
![Page 11: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/11.jpg)
CRYSTAL RADIOS WERE ALSO BUILT BY PRISONERS OF WAR IN VIETNAM.
![Page 12: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/12.jpg)
CRYSTAL RADIO KITS ARE STILL MADE TODAY.THERE ARE EVEN CRYSTAL RADIO CLUBS!
![Page 13: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/13.jpg)
HOW DOES A CRYSTAL RADIO WORK?
? ?
![Page 14: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/14.jpg)
AN ANTENNA GATHERS RADIO SIGNALS.
![Page 15: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/15.jpg)
THE INDUCTOR AND CAPACITOR FORM A RESONANT CIRCUIT THAT TUNES THE RADIO TO A STATION.
![Page 16: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/16.jpg)
RADIO SIGNALS POWER THE CRYSTAL DIODE.
![Page 17: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/17.jpg)
THE CRYSTAL DIODE DEMODULATES THE SIGNAL.
(detector)
![Page 18: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/18.jpg)
DEMODULATES MEANS TO TAKE THEORIGINAL INFORMATION (AUDIO) FROM
THE SIGNAL.
![Page 19: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/19.jpg)
THE SIGNAL IS SENT TO THE EARPHONES.
![Page 20: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/20.jpg)
How the parts connect
● Antenna
● Capacitor
● Inductor – coil
● Diode 1N34 –
“the cat whisker”
● Earpiece
● Ground
![Page 21: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/21.jpg)
Does it work? We start with the capacitor
![Page 22: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/22.jpg)
What is a Capacitor?● A capacitor is made of two conductive surfaces
● Separated by a non-conductive material
● Non-conductive materials can be air, plastic, paper and many others
● The value of the capacitance is determined by the surface area of the conductive material AND the
quality of the non-conductive material and the distance between the conductive surfaces
● In a direct current circuit the capacitor “stores” or blocks the current flow
● In an alternating current circuit the current is passed through the capacitor
![Page 23: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/23.jpg)
Building a Capacitor
● Step 1
● Assemble
the parts
![Page 24: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/24.jpg)
Building a Capacitor● Step 2
![Page 25: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/25.jpg)
Building a Capacitor● Step 3
![Page 26: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/26.jpg)
Building a Capacitor● Step 4
![Page 27: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/27.jpg)
Building a Capacitor● Step 5
![Page 28: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/28.jpg)
The Inductor● About 130 turns of enameled copper wire
● Enamel is a high quality insulator
● It looks like bare wire
![Page 29: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/29.jpg)
The “cat whisker” 1N34 diode● See B in the chart
● Current flow from Anode to Cathode
● Anode Cathode
![Page 30: SOMERSET AMATEUR RADIO CLUB PRESENTS](https://reader031.vdocuments.us/reader031/viewer/2022012506/61817232ebc1ec48797f16a0/html5/thumbnails/30.jpg)
No cats will be injured
No batteries will be needed
Ready to put it together?