This 10 A solid state relay was found in a 1980s documentation. It can work as a shield and implemented with modern equivalent transistors.
This is the basic full-scale circuit of an LM3914 for voltage measurement or voltage triggering and...
We found this circuit in the October 1992 Radio Electronics magazine. The frequency is given by C1...
Although most common piezoelectric transducers have a reduction in performance at frequencies...