Radio with amplifier (CB20486E)

We found this circuit in a publication of 1991. The audio amplifier is an operational that admits equivalent.

Regenerative WWV receiver (CB20272E)
WWV is the American broadcaster of hourly signals and frequency standards that operates at 3.5...
Active Filter (CB5109E)
This active crossover filter was obtained from the component manual used. Below is the performance...
Fast Phototransistor (CB14655E)
The circuit shown in the figure has a quick response using T2. The trimpot adjusts the...