Make a Crystal Radio Receiver - Part 3 - The Scout's Crystal Set Explained - How does it Work?

A walk through of the functioning of the Scout's Crystal Set.

Explained is the schematic, the tuned circuit, resonance, antenna length, the role of the inductor, loose coupling, rectification, and demodulation.

These are the notes I have taken before building the set and the considerations and observations I recorded during and after building the set.

Please note that in the original schematic, the coil is
22 gauge = 0.7 mm.
90 turns of 22 gauge = 7 cm
but in the project here, I wound more, 9 cm, to allow to tune to frequencies down to 540 kHz, in conjunction with the maximum capacity of 365 pF used here.

The lowest frequency in the AM band before 1923 was instead 690 kHz, and 90 turns would have sufficed.


00:00 Sources / Literature
00:50 Schematic
03:55 Other schematics
06:22 Values of components
07:05 Calculating the values of the LC circuit
12:45 Filters
13:19 Resonant Frequency
15:19 Increase of amplitude as the frequency approaches resonant frequency
15:36 Antenna length
29:10 Loose coupling
30:43 Demodulation
34:40 Bloopers


The Scout's Crystal Set presented in Part 1:
   • Make a Crystal Radio Receiver - Part ...  

Making and Building the Scout's Crystal Set is shown in Part 2:
   • Make a Crystal Radio Receiver - Part ...  

The Schematic is described in Part 3:
   • Make a Crystal Radio Receiver - Part ...  

Winding the coil for a crystal radio is shown in Part 4:
   • Make a Crystal Radio Receiver - Part ...