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Simplest R/C Circuit
A simple and effective receiver for actuating garage doors, starter motors,
alarms, warning systems and numerous other possibillities. The SCR, which has a
very low trigger current of 30 uA is typical -- it requires an input power of
only 30 uW to activate the relay. A high Q tuned antenna circuit assures
rejection of spurious signals. A whip or wire antenna is adequate up to 100 feet
from a low power transistor transmitter. A momentary-off switch resets the
circuit.
The circuit specifies a whip or wire antenna which
just means a solid piece of wire 6-12 inches long (15-30cm). The antenna coil is
experimental but you can start with 10 to 12 turns of #22 (0.7mm) magnet wire,
and 5/16" (8mm) coil diameter. Antenna wire is soldered at 1/2 turn of the coil
and the gate of the BRY35 is soldered about halfway the coil. This circuit will
transmit up to 100-feet with the above specifications @ 30uA.
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