This circuit was found in a 90s Integrated Circuits Data Book. It interfaces a data line with a CMOS input, being powered by 5V. Can be used as a shield.
Found in a Popular Electronics from the 90s, this circuit can act as a transmitter for an audio...
With the circuit shown in the figure, the frequency of a 5 MHz oscillator controlled by crystal can...
This circuit with two HT2030s powers 6 LEDs in a decorative flashing system. The circuit is from...