[sdiy] 4051 spikes

[The Old Crow]

   From what I recall, 405x analog switches are make-before-break, so in 
order to minimize glitching the inhibit input needs to be used to 
disable the output between channel changes. --Crow

On 4/25/2015 4:38 PM, florian anwander wrote:
> Hello,
>
> I have setup today a simple test circuit for a batch of 4051 
> (HEF14051BCP to be exact), which I received for free. While testing I 
> found that all 4051 I own (not only the ones from the received batch) 
> show some short feedthrough of the common signal at outputs 3 and 5 at 
> not addressed times.
> A picture of the scope image can be found here (signal from output 3)
> http://fa.utfs.org/diy/CD4051_1.jpg
> The test setup can be seen here:
> http://fa.utfs.org/diy/CD4051_2.jpg
> It is simply a 4069 as oscillator, a 4520 as address counter and the 
> 4051.
> One has to turn down the clock rate into the audiorange, to make this 
> vanish.
>
> Is this normal? Is it caused by the breadboarding setup?
>
> Thanks for any insight.
>
> Florian
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