Found in a 1967 Electronic Design, this circuit can detect pulses as narrow as 0.2 us. Active components can be replaced with modern equivalents.
The frequency of this astable depends on the capacitor that can be changed over a wide range of...
This circuit is from a documentation from the 90s. The transistor can be any general-purpose FET...
In the figure we have one of the many options found in this section for an intercom using ordinary...