This rarity is from a 1926 publication. The galena detector (D) can be replaced in a modern version with a 1N34 diode or equivalent. The tuning is in series and C1 can have 1nF since at the time, homemade capacitors were specified in centimeters. The variable can be obtained on an old AM radio. The bobbin can be wound with 60-80 turns of wire 28 in a 2.5 cm diameter tube (cardboard or PVC). Below the original page of the publication in 1926.
