This switched power supply was found in a 70s documentation. The basic components are from that time. The circuit operates at 200 kHz and has a ripple below 200 mV.
This circuit that emits siren sound can be used in a fire alarm. We found it in an old American...
This circuit generates sinusoidal signals from 15 Hz to 15 kHz. The circuit is from Electronics Now...
In the figure a circuit that is the basic application of NE567 for the detection of a tone applied to...