This two-transistor circuit is from a December 1964 Radio Electronics. Modern transistors can be tested. The headphone must be high impedance or crystal with a 2k2 resistor in parallel.
This receiver receives signals in the 17 MHz or 11-meter range and can be used as a base for an...
The operational amplifier used in this circuit is not common today. The frequency is given by the...
In the figure we have the way to add hysteresis to an operational amplifier. The relationship...