Crystal Radios

1. Parallel-tuned, series-fed configuration:

Parallel-tuned, series-fed Crystal Radio circuit

The diode-clipped parallel-resonance voltage is output to the phones. 

High-impedance diodes and phones are required to match the high impedance of the

parallel-resonant circuit. 

This configuration is suitable for reception of distant, weaker stations.

2. Series-tuned, shunt-fed configuration:

Series-tuned, shunt fed Crystal Radio circuit

The diode-clipped series-resonance current is output to the phones. 

Low-impedance diodes and phones are required to match the low impedance of the series-resonant circuit. 

This configuration is suitable for reception of nearby, more powerful stations.

3. Series-tuned, shunt-fed variant:

Series-tuned, shunt-fed Crystal Radio variant

This is a variant of the above series-tuned, shunt-fed configuration. 

Using low-impedance diodes and phones, it delivers identical performance.