|Another Crystal Radio Variant|
The coil is (280 + 40) turns of 30 SWG enamelled copper wire, close-wound as shown. The PVC variable capacitor is mounted on one of the end caps.
|Another Crystal Radio Variant - Schematic|
The OA79 diode feeds a pair of sensitive balanced-armature phones.
Using a wire antenna 60' long, reception of the 612 kHz - 200 kW local AM broadcast station is quite good. Headphone current, measured using a 1mA FSD 60 Ω meter, is 300 μA.