[sdiy] comparators vs. clamping diodes as gate inputs to microprocessor?

[Seb Francis]

Danjel van Tijn wrote:
> I have been exploring lot's of different options for interfacing
> gates/clocks  and CV to microprocessors.
>
> Several people on this list have been very helpful and offered some
> good examples.
>
> However I am split as to whether to use a comparator or a pair of
> clamping diodes for the gate/clock inputs. The clamping diodes simply
> ensure that the gate voltage falls into a strict voltage range but the
> comparator would at least allow weak clock sources (i.e. low voltage)
> to be boosted...not sure if that is really relevant.
>   

Read the input specification of your microprocessor.  It probably 
accepts fairly low voltages already.  Do you really need to add extra 
components/complexity?

Incidentally if you did want to accept very low input signals a single 
transistor would do the job.

> Anyone have thoughts on this? Most of the solutions I have seen
> involve using comparators but Seb's clamp diode inputs (on his
> website) look like a  nice and simple solution (and cheap).
That'd be:
http://burnit.co.uk/sdiy/files/digimod/Digi-Mod-v1.1.pdf
(page 3)

Seb