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MiniFM-Oldie Receiver

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zlatkoMM

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There is a nice schematic in Fig.5, but the loop is hand sensitive. To overcome this disadvantage and because i dislike tapped coils,
i've synthesized an aperiodic preamp like in Fig.6 and an colpitts-like common base oscillator with feedback from collector to emitter,
coupled them by small C and the remaining parts from Fig.5 to this schematic:
 

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betwixt

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I'm not sure what fig.5 and fig.6 refer to but the schematic shown is a super-regenerative receiver so it relies on the self quenching of the second transistor to give it sensitivity. If you apply a different oscillator to it you get something more akin to a zero IF receiver with a pulse counting detector which would be far less sensitive.

Brian.
 

zlatkoMM

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This receiver can work in two mode.
As regenerative or super -regenerative what depends on base current biasing.
Most of zero IF receivers are synchro-dyne types and as such are not in co-relation with pulse-counting
detectors.Pulse counting receivers are not zeroIF types than use very low IF such as 70kHz, 120kHz .
and are sort of superhets radios.
One very good is a microFM2:
 

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