This integrating circuit multiplies the time that can be obtained with a 555 timer. We find it in an Electronic Design from the 90s. The circuit uses components that are still common today.
This 3-component circuit uses an analog indicator. We found it in an old publication....
Pulses in sequence can be generated from a clock input using the circuit shown bellow. Outputs A,...
This circuit simulates a low-level siren and can be supplied with voltages from 5 to 15 V....