I've read about large coil crystal radios and always wondered if they were any good and worth the trouble. I bought a couple embroidery hoops and wrapped one with single strand copper, and the other with Litz wire. I tested them against a regular coil crystal radio of the same circuit layout. There were assumptions, leading to mistakes; in the end it worked out!
MATERIALS
- 500uH variable capacitor (normally 365uH)
- Capacitor mount
- Litz wire (10/46)
- 309mm embroidery hoop
- Crystal earphone
- 1n34a diode
- 10k to 30k ohm resistor
- Fahnestock clips (optional)
- Screws, washers
- Base 15cm x 10cm x 3cm
- Mast 40cm tall x 9cm wide (paneling)
- Zip ties
- Thread
- White glue
- Wire ends (optional)
- Shrink wrap (optional)
OTHER CRYSTAL RADIO VIDEOS
World's Simplest Radio [ Ссылка ]
Best/Easiest DIY Crystal Radio - No Batteries, No External Power [ Ссылка ]
My New Favorite! Crystal Radio with Antenna Tuner [ Ссылка ]
Crystal Radio--No More Variable Capacitor Designs? Crystal Radio--1 Variable Capacitor, 3D Printed (4K) [ Ссылка ]
Crystal Radio--Ferrite Coil Model #2 [ Ссылка ]
Crystal Radio, Capacitive Tuning - WORKS GREAT! [ Ссылка ]
Crystal Radio DIY Cat Whisker--Wood, Brass, Stainless [ Ссылка ]
Crystal Radio DIY Cat Whisker Ver 2.0 Pt 2 [ Ссылка ]
Wiper Crystal Radio Selectivity Upgrade #1 [ Ссылка ]
My Crystal Radio Wiper-Type Selectivity Upgrade #2 [ Ссылка ]
WARNINGS:
- Never connect radio to any source of power. Not house current, nor batteries, nothing!
- Never use the radio during lightning storms.
- Never run an antenna over or near power lines.
- Disconnect antenna and put lead outside when not in use.
- Never ground to electrical items, plugs or similar.
- If you don't know, learn first or don't do it.
CHAPTERS
00:00 Intro
02:40 Calculations
14:07 Construction details
20:09 Compare single strand copper hoop to original air core radio design
23:07 Litz hoop
24:28 Construction final
