TA7642 AM radio kit 4 includes:
1 – Ceramic Earphone (Piezoelectric Earphone , Crystal Earphone)
1 – TA7642 IC
1 – 100K Resistor
1 – 1K Resistor
1 – .1uf Capacitor
1 – .01uf Capacitor
1 – 680uh Loopstick Antenna Coil with tap at 470uh
1 – Plastic Variable Capacitor 60pf /141pf
1 – AA Battery Holder
TA7642 Kit Number 4 has a 680uh coil with a tap at 470uh.
The MK484 Kits are TRF ( Tuned Radio Frequency, Tuned RF ) type receivers. This the most basic type of radio receiver with no regeneration or re-genitive feedback. The variable capacitor and antenna coil form a “Tank” circuit that tunes the radio stations frequency then the MK484 amplifies the radio stations radio frequency then “Rectifies” (Converts to Audio) it then amplifies the audio and powers the Earphone.