[sdiy] converting a 10v p to p to a 0-5 volt signal

[Adam Schabtach]

Aside from range scaling, I'm still looking for a good protection circuit
for microcontroller inputs. I want hard clipping at 0V and 5V to protect the
micro. I've seen various solutions described on this list, but when I put
them into SPICE I have always found some flaw, such as the lower limit
actually being one diode-voltage-drop below zero rather than zero. I'd be
very happy if I could find some nice solution to this problem so that my
micro-based modules can protect themselves rather than having to depend upon
my poor memory to avoid being subjected to unacceptable voltage ranges. :-)

Or, putting it another way: converting 10Vp-p to 0-5V with op-amps is a fine
solution, but as soon as you add two 10Vp-p signals together (e.g. mixing
two LFOs) the input range can easily exceed 10Vp-p and hence the output
range will also exceed 0-5V.

--Adam 

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> Jason Proctor
> Sent: Tuesday, May 19, 2009 6:50 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] converting a 10v p to p to a 0-5 volt signal
> 
> i did exactly this for my Arduino module. it bidirectionally 
> interfaces a +/-5v signal to the micro's 0-5v range.
> 
> turned out to be pretty easy - on the way in, chop the signal 
> in half, and bias with +2.5v. then reinvert. on the way out, 
> do the opposite. 1 dual opamp each way.
> 
> lmk if you want the details.
> 
> (i should also thank Tom Wiltshire here for his help getting 
> me off the ground with this stuff.)
> 
> 
> >tonight i was looking at my scope
> >
> >Checking the input into a circuit that was only able to take 
> 0-5 volts
> >
> >Sure enough, the signal was between 0 and 5 but the sawtooth 
> was clipped.
> >
> >So i am looking for a input block that can take either
> >5vp to p or 10v p to p (or any synth signal)
> >and spit it out as a 0-5 signal without squaring the top.
> >
> >
> >anyone know of a good circuit for this?
> >
> >thanks
> >
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