We found this circuit in a 1985 documentation. The transformer is an old TV flyback that has an exposed part of the core, where 10 to 20 turns of common wire are wrapped.
An FM receiver with good sensitivity and with acceptable sound quality in the strongest stations, can...
This filter has a factor Q = 10 (selectivity), and its frequency can be changed as shown in the...
With the capacitor used, this circuit provides delays of 40 to 60 seconds. Larger capacitors can...