We found this circuit in a Poptronics from the 90's. Equivalent operational amplifiers can be used. The circuit must be supplied by a symmetrical source.
This circuit generates pulses whose duration determines the position of a remote-control servo. The...
This circuit uses a piezoelectric tweeter to emit a powerful continuous sound above the audible...
This circuit generates sinusoidal signals that depend on the input oscillator. The circuit is from...