circuit that disconnects a connection
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. A simple pulse extender.

How it works:


When IN goes high BUF1 output goes high. C1 is charged through D1. BUF2 turns on.
When BUF1 goes low C1 starts discharging through R1.
If VC1 drops to about 1/3 of supply voltage then BUF2 will turn off. The time taken for this is approximately \$ \tau = RC \$. You want a 5 x 0.1 s = 0.5 s delay. With a 10 µF capacitor you can calculate \$ R = \frac {\tau}{C} = \frac {0.5}{10^{-5}} = 50\ \text k\Omega  \$.
Meanwhile, if another pulse comes within 500 ms the circuit is reset.


Use Schmitt trigger gates for the buffers. If you are using inverting gates then reverse D1.