PulseExt01.zip

Design by: 6706

This  simple circuit extends the length of a short duration positive pulse of a few milliseconds.  It is intended for interfacing with digital inputs on devices where the program scan time exceeds the length of the input pulse and where no interupt function is available. 

Several are currently in use providing interface between a hall effect sensor and an industrial PLC 24Vdc sinking input.

Note that a high impedence load is assumed.  This circuit will not reliably run an electromechanical relay or similar.

BOM:

  • 3 x NPN transistor (BC337 or similar)
  • 2 x 3mm LED (any colour you like)
  • 1 x 10uF 50V electrolitic capacitor
  • 1 x 3k3 .25W resistor
  • 3 x 5k1 .25W resistor
  • 1 x 10k .25W resistor
  • 1 x 51k .25W resistor
  • 1 x 100k .25W resistor
  • 2 x 5mm 3 way screw terminals
51k resistor gives an output pulse length of about 250mS.  To reduce output time, lower resistor value.  To extend, increase resistor value.


Price Varies

Size
5.0 cm x 5.0 cm
PN
101-782