This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at the end of the timer, erasing the other. The timing can be increased by increasing C1.
Suitable for the use with sensors, this circuit from National Semiconductor appears in other...
Using transistors at the time, this circuit was found in a 1970s documentation. Transistors support...
This second-order low-pass Salen-Key filter was obtained from an American 1980s documentation. Formulas...