Data Sheet

389. FM Radio Channels
Build the circuit to the left, turn on the switch (62) and press the press
switch (61), and you will hear some FM radio stations from the speaker
(93). You may have to press the press switch (61) connected to CH– to
get the FM receiver to scan for a channel. For best FM reception, hold
the open end of the spring wire (9) in the air.
FM radio channels are spaced 200 kHz apart. This means that
theoretically there could be about 100 FM channels in a given city/
area. The FM channels are actually numbered from channel 200 to
channel 300 starting with channel 200 centered at 87.9 MHz, channel
201 at 88.1 MHz,…,up to channel 300 at 107.9 MHz. Have you ever
noticed that all the FM radio channels you listen to ended in an odd
number? Now you know why!
390. FM Radio in Lower Volume
Build the circuit to the left, turn on the switch (62), and you will hear
some FM radio stations from the speaker (93) and see the heart LED
(69) ash. You may have to press one of the press switches (61) to get
the FM receiver to scan for a channel. For best FM reception, hold the
open end of the spring wire (9) in the air.
The volume from the speaker (93) is lower than in the previous project
because the heart LED (69) introduces resistance which reduces the
voltage levels seen across the Speaker[93].
-145-
+
–