Radio with amplifier (CB20486E)

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

Crystal Oscillator Using an Inverter (CB119E)
This page shows a crystal oscillator for 2 MHz. Other frequencies can be produced depending on the...
Monostable TTL 7400 (CB9424E)
This circuit is from a 1970 publication. The time constant is given by 1.3R x C where R is the...
4 W amplifier TDA1904 (CB15219E)
The supply voltage range of this circuit ranges from 4 to 20 V and the power depends on the chosen...