[sdiy] The annual I/O impedance/protection thread!

[Tim Parkhurst]

On Sun, Jul 10, 2011 at 6:22 AM, Justin Owen <juzowen at googlemail.com> wrote:
> Hooray!
>
> This is one of those topics that keeps coming up here on SDIY so I've uploaded a few schems based on the 'standards' and the conversations that have gone on here in the past.
>
> Hopefully your answers and comments will be helpful to more people than just me.
>

Okay, I've just woken up and haven't had my tea / coffee yet, but it
looks to me like on #3 you're trying to limit the output to the 0 to
+5V range (blocking diode on the output, 4V7 zener to ground). No
reason to do this unless you're interfacing to a microprocessor or
other logic-level circuits. If you're setting these up for processor
I/O, then that's a different set of restrictions. Also, you'll need
another op amp in the summing circuit. The circuit as shown will give
you a 0 to -5V out of the op amp (although I think with the blocking
diode as shown you won't get anything out).


Tim (going to have some coffee and watch the F1 race, then maybe I'll
be awake) Servo
-- 
"Sire, the church of God is an anvil that has worn out many hammers."
- H.L. Hastings