This circuit was obtained in an Electronics World of 1968. The operational amplifiers ones are types of the time, no longer used today. The circuit responds from less than 20 Hz.
This audio-driven relay was published in the July 1977 issue of Radio Electronics magazine. The...
This circuit can be used for signaling a panel with a common incandescent lamp. The lamp will...
This crystal oscillator is indicated for the calibration of IF steps of common radio receivers. The...