This circuit retriggers when a new pulse arrives. It does this by discharging the capacitor. The circuit is from a documentation from the 80s. The transistor can be any general purpose one.
This conventional series reducer circuit reduces the voltage of a 12 V battery to the selected value...
In the figure we have a converter that generates a negative voltage from a positive voltage...
This circuit covers the bands from 1.8 to 150 MHz, with plug-in coils whose characteristics are...