Any OR gates with good noise immunity?

Hi all,

I made the foolish mistake in a recent instrumentation design of
routing a copper track from one board to another via a common 'mother'
board and associated edge connectors, straight into the input of a 4071
OR gate. The output of this gate clocks a 4015 4-bit shift register.
The circuit 'works' fine in the lab but the problem lies in the
equipment installation, where a number of noisy mains-powered solenoid
relays manage to falsely trigger the shift register for around one in
every ten actuations. I suspect that the long copper route is acting as
an ideal aerial for this noise, even though the entire circuit is
housed in a grounded metal box.

Are there any 4071 plug-in equivalents with schmitt-trigger inputs, or
other variants with better noise immunity? A less eloquent option would
be to insert two series connected schmitt-trigger NOT gates (of the
40106 variety), but space is already at a premium for such a
'piggy-back'. Any suggestions appreciated.

Thanks,
John.

.

Relevant Pages

  • Re: Any OR gates with good noise immunity?
    ... >routing a copper track from one board to another via a common 'mother' ... The output of this gate clocks a 4015 4-bit shift register. ... >an ideal aerial for this noise, even though the entire circuit is ... >be to insert two series connected schmitt-trigger NOT gates (of the ...
    (sci.electronics.design)
  • Re: Any OR gates with good noise immunity?
    ... >> routing a copper track from one board to another via a common 'mother' ... The output of this gate clocks a 4015 4-bit shift register. ... >> an ideal aerial for this noise, even though the entire circuit is ...
    (sci.electronics.design)
  • Re: Any OR gates with good noise immunity?
    ... > routing a copper track from one board to another via a common 'mother' ... The output of this gate clocks a 4015 4-bit shift register. ... > be to insert two series connected schmitt-trigger NOT gates (of the ... input and hack the track at the input to insert a series 10K resistor in it. ...
    (sci.electronics.design)