Eight RETRO RADIO, Instructions Manual, Page: 6 / 36

FM board
Voltage regulator
The FM board
is the essential component of this radio. It
contains an integrated circuit and many tiny pre-soldered
capacitors and resistors. You can easily recognise two printed
coils and the upright variable capacitance diode. There are six
pins to connect the board with the breadboard and thus the
other components. It is important to supply the radio board
with an operating voltage of only 3 V. It must never be con
-
nected directly to a 9 V battery. Instead, a voltage regulator is
required.
The
HT7530 voltage regulator provides a stable voltage of 3 V.
Its three legs are not interchangeable. The middle leg is the
input. It connects to the positive terminal of the 9 V battery.
The output, i.e. the right pin, then provides a stable voltage of
+3 V. The third pin connects to a shared negative terminal.
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