The circuit shown is from the National Semiconductor Linear Applications Handbook of 1994. using ADC0808. The circuit can handle data from up to 4 transducers with an 8-bit output.
This stethoscope or hearing aid amplifier has excellent gain. It was found in Popular Electronics from...
Found in Fairchild documentation from the 90s, this circuit generates signals with the...
This configuration, widely used in our articles and on this website, uses a 555 to control a relay...