[TriEmbed] Electric Fence monitoring

Scott Hall scottghall1 at gmail.com
Wed Jul 1 11:17:34 CDT 2020


You could use a 74LVC245 tristate driver (I'm stuck with a bunch of them)
or 74LCX07 hex buffer or 74LCX541 octal buffer that are 5V input tolerant
and drive 3.3v outputs, but you would loose the analogous of the signal --
it would be conditioned to a digital signal.

For a recommended solution, look at Microchip's tipsheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/chapter%208.pdf,
specifically solution #12 for a resistor divider, or for your circumstances
an active transistor clamp like solution #11.


On Fri, Jun 26, 2020 at 11:19 PM The MacDougals via TriEmbed <
triembed at triembed.org> wrote:

> My electric fence monitoring project is making progress.
>
>
>
> Attached is a scope shot of the signal I am trying to monitor.
>
> There are two issues I want to address before putting this signal on the
> A0 pin of my ESP8266 development board (D1 mini).
>
> The spike to ~5 volts is concerning.  I think I can use a 3.3v Zener diode
> to suppress this.  Installed between my signal and ground with the banded
> end away from ground.
>
> The negative lobe of the signal is also concerning.  Can I just use a
> diode in series here?  Banded end toward the A0 pin.  I can adjust the
> voltage up a bit to compensate
>
> for voltage drop across the diode.
>
>
>
> I have drawn up a schematic of what I think is the solution.
>
>
>
> Thanks for any comments.
>
>
>
> ---> Paul
>
>
>
>
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-- 
Scott G. Hall
Raleigh, NC, USA
scottghall1 at gmail.com
*Although kindness is rarely a job, no matter what you do it's always an
option.*
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