Friday, October 8, 2021

Update on 1.5 volt receiver

A question about this circuit started me looking at it. It uses a 9 volt supply but why? The audio amp and Vcap tuning require 9 volts. The detector uses 1.4 volt.

 Using this portion of the circuit with my 1.5 volt hearing aid amp give good results. 

I would substitute a 200 ohm resistor for R1 and use a lower value pot for the regen. My test determined R2 could be around 10K. With the 100k pot it operates close to the pots low limit.

I did assemble the DBM and Lambda Diode set. That is still an option.

I am considering a discrete component Gilbert Cell. While this is a good option it would require a higher supply. 

Someday maybe the Gilbert Cell, Lambda Diode, and earbud amp will find their way onto a board. The Lambda Diode does not need a tapped coil so it would be possible to make a socket to use plug in coils. The Gilbert Cell provide conversion gain. This could be the beginning of an all band receiver. It could use one Vcap and plugin coils.

Some food for thought.

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