Circuit is based on a 555 bi-polar timer, but a 7555 could also be used.

T2 is an inverter to allow positive-going pulses to trip the circuit.

C2 prevents the 555 from pulling the PIC32 ~MCLR line low at power-up.

C1 is the main timing capacitor.  Do not use tantalum type - they dislike being shorted out.

C4 sets the output pulse time.  Increase this in value for a longer output pulse
or remove it altogether for a short output pulse.

C6 decouples the 555 Control Voltage pin, as per the 555 datasheet.

1M trimpot along with R2 set the time delay.  Change this trimmer for 2M for 
longer time delays.  It is preferable to change the trimpot, rather then increasing
the value of C1, because T1 shorts out C1 when it switches, and large value
capacitors potentially could cause issues when shorted in this way.

