How high an input impedance? In a recent project I did I had a similar
problem, I simply used a 1Mohm resitor and a zener diode. This might not be
high enough for your though, I don't know. TTYL

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Pic Dude
> Sent: Tuesday, March 05, 2002 18:33
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE]: Limiting signal level
>
>
> Had built an analog device some months back with a comparator
> chip to convert a variable-frequency, variable-amplitude sine-ish wave
> signal to a digital square-wave signal with just variable frequency.
> The comparator just switched the output from Lo to Hi when the input
> crossed a certain threshold.  Worked well -- a most exhilarating
> feeling since my analog-circuit knowledge is not too great.
>
> The only thing I was not sure of was the max amplitude of the input,
> but I've been thinking about it again since I heard recently that it
> could go as high as 24V or more, and power supply is only 8V to the
> comparator.
>
> Keeping the same 8V supply, is there an easy way to pre-"clip" or
> pre-limit the input to approx 8V before it gets to the comparator,
> but still maintaining a high input impedance?
>
> Thanks,
> -Neil.
>
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