[sdiy] CV --> microcontroller, how to limit input voltage?

[Tim Ressel]

Yo,

This is a standard method of clamping inputs. However
it is wise to place a current limiting resistor before
the diodes or else they will draw lots of current if
they conduct. I use 1K for this.

--Tim

--- The Old Crow <oldcrow at oldcrows.net> wrote:
> 
>   Just use a couple of diodes.  For example: K of D1
> to +5V supply, A of
> D1 to I/O pin.  K of D2 to I/O pin, A of D2 to GND. 
> These will clamp the
> input to 0~+5V (well, -0.7 to +5.7)..
> 
>   I typically use 1N4001s, but if the current load
> is light switching 
> diodes (1N4148) are fine.
> 
> Crow
> /**/
> 
> On Sat, 10 May 2003, Bret Truchan wrote:
> 
> > * If a microcontroller I/O pin is configured for
> input, an incoming voltage 
> > signal doesn't peak over 14 volts  
> > * If the microcontroller I/O pin is configured for
> output, it still works. 
> > (The output will always be 5Vfrom the
> microcontroller.)  
> 


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