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    • World's Simplest Radio (4K)  
Best/Easiest DIY Crystal Radio No Batteries, No External Power    • Best/Easiest DIY Crystal Radio  No B...  
My New Favorite! Crystal Radio with Antenna Tuner    • My New Favorite!  Crystal Radio with ...  
Crystal RadioNo More Variable Capacitor Designs? Crystal Radio1 Variable Capacitor, 3D Printed (4K)    • Crystal Radio1 Variable Capacitor, ...  
Crystal RadioFerrite Coil Model #2    • Crystal RadioFerrite Coil Model #2 ...  

Crystal Radio, Capacitive Tuning WORKS GREAT!    • Crystal Radio, Capacitive Tuning  WO...  
Crystal Radio DIY Cat WhiskerWood, Brass, Stainless    • Crystal Radio DIY Cat WhiskerWood, ...  
Crystal Radio DIY Cat Whisker Ver 2.0 Pt 2    • Crystal Radio DIY Cat Whisker Ver 2.0...  
Wiper Crystal Radio Selectivity Upgrade #1    / 8r8mjpz1  
My Crystal Radio WiperType Selectivity Upgrade #2    • Crystal Radio WiperType Selectivity ...  


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