This circuit was found in the October 1987 Radio Electronics magazine. The circuit is a PWM control with a 555. It appears that the 555 is missing a connection that would be pin 4.
The quadrature oscillator is another type of phase shift oscillator, where each of the three...
The power supply shown in the figure provides output voltages in the range of 1.2 to 25 V with...
The frequency ranges that this receiver can tune in depend only on the coils. For medium waves L1...