From: me@somewhere.invalid   
      
   Dimitrij Klingbeil  wrote:   
      
   >On 2018-09-12 18:54, Terry Pinnell wrote:   
   >> Is there any consensus on the neatest circuit to take a noisy push   
   >> button signal and output a clean rectangular pulse?   
   >>   
   >> Searching through my ancient (paper) files I found dozens, but my   
   >> scribbled notes on many show that when tested I'd found lots failed,   
   >> allowing some noise to reach the output. My starting assumption is a   
   >> simple CR filter in front of a Schmitt. But before I head for the   
   >> shed and start bread boarding I'd much appreciate any recommendations   
   >> please.   
   >>   
   >> Terry, East Grinstead, UK   
   >   
   >The good old 555 timer works nicely in this application. It has a very   
   >wide hysteresis (from 2/3 of Vcc to 1/3 of Vcc) that makes the circuit   
   >immune to noise and unwanted re-triggers. There is a push-pull logic   
   >output available as well as the open-collector "discharge" one, and   
   >everything apart from the 3 timing-related passives is integrated. For   
   >CMOS logic compatibility from 1.5 V supply and up, there's the LMC555.   
      
   Thanks Dimitrij, that looks like my favourite.   
      
   (Sorry for delay; this post was my first reply, but I didn't spot it had   
   somehow got stuck in the outbox.)   
      
   Terry, East Grinstead, UK   
      
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