On 9/26/2017 7:49 PM, T i m wrote:
Too much information (variables) for me in most cases mate.;-)

You keep missing it.

Here it is again.
The simplest is a 20K resistor in series with a 10v zener diode.
Use a low current Zener so the knee works right at low values.
Something like this:
http://www.mouser.com/ds/2/395/BZX55C2V0%20SERIES_D1610-1099630.pdf
Note, this is a DO-35 package.


--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com