Elenco 130-in-1 Electronics Playground - Manual (Page 132)

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This AM radio station circuit lets you actually transmit
your voice through the air.
When you completed wiring the circuit, tune your AM
radio a weak station or place with no stations. Place
the AM radio close to the circuit since the signal can
only transmitted a few feet. As you talk into the
speaker adjust the tuning capacitor, until you hear
your voice on the radio
The audio signals produced as you talk into the
speaker are amplified by transistor Q1. These
signals control the amplitude of the RF oscillator
signal. The antenna and tuning capacitor tune the RF
signal to the setting on your AM radio dial and it is
transmitted through the antenna.
The amplitude of the RF signal is controlled by
transistor Q2. The RF signal is amplified by NPN
transistor (part of the RF oscillator) before the AF
(audio frequency) signal modulates it.
Notes:
EXPERIMENT #111: AM RADIO STATION
Wiring Sequence:
1-29
2-30
3-111
5-7-90-42-119
6-12-47-ANT
8-11-99
40-112-94
41-43-93-78
77-44-131
45-79
89-100-46
48-80
121-122
124-132
Schematic