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Feb/14/2012
A interesting Reflex amplifier combine with doubler detector. One BJT transistor use as both RF and audio amp. It'a a typical cost saving technology back to the ages that reflex receiver born.
VCC : 7.2V to 8.4V
C2, D1,D2 form a doubler detector
audio signal re-inject to T1's base while pass though the double voltage detector D1/D2.
R5 with 47k pot provide bias current for D1, D2
Final audio signal passthrough RFC1, driven the 600 ohm earpieces.
T1 couple to tune tank via 15T link, keep the loaded Q, this ensue some selectivity.
performance
performance
Indoor receiving is hard: only near the window could catch few strong stations.
impossible to receive other city's station
with loop antenna is much better than the loop-stick antenna
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