> > I am working with an optical encoder which outputs a voltage
> > between +0.35VDC and +1VDC. What is the easiest low
> > component count method for getting a clean 0V to 5V pulse
> > from this to use as an input to the PIC?
>
> If those voltages are reliable levels then a transistor will work well with
> 3 resistors.
>
> If they aren't reliable then a bit of design will still produce the goods.
> Ask with more details if this is the case.
>
> A 555 as suggested MAY work but needs design.
>
> TRANSISTOR. DESIGN
>
>     Cheap. Easy. Compact. Learn something. Works.
>
> NPN small signal. Just about anything. (2N2222 or whatever)
>
> R1 Input resistor 10k to 100K from input signal to base.
> R2 Pulldown / leakage shunt 100k to 1 megohm base to ground.
> R3 Collector resistor 10k to 100k collector to Vdd.
> PIC pin to Vdd.
>
> R2 can perhaps be omitted but its good to have it.
>
> Cheap. Simple. Works if voltages are as stated.
>
> R1 larger makes less load on signal
> R2 at least 10 x R1 (more OK)
> R3 could be 1M probably but 100K OK.
>
> If this signal is very high speed things will get more complex. The above
> should probably work at eg 10 kbps without a thought.
> Maybe at 100 kbps
> Almost certainly not at 1 Mbps
>
>
>
>         Russell McMahon


The speed of the encoder will never reach those speeds. This sound like it will do the
trick and I do have a handfull of 2SC536 NPN transistors (TO-92)!
Thanks to everyone for their input....now on to the breadboarding!

Regards,
Stephen D. Barnes

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body