On Saturday, 23 September 2017 17:52:35 UTC+1, Jeff Liebermann wrote:
On Fri, 22 Sep 2017 15:39:14 -0700 (PDT), tabbypurr wrote:
On Friday, 22 September 2017 05:22:46 UTC+1, Foxs Mercantile wrote:
On 9/21/2017 10:59 PM, tabbypurr wrote:

simple but time consuming producing a new dial paper

With the low current Zener, it doesn't look like that will be
necessary.

Oh, you've found a zener that's 10v +/- 1%?
NT

The meter isn't even that accurate.

We don't know the meter's accuracy. 1% is common enough, but it might be worse. (For all we know it might even be a moving iron thing.)

You're not going to be able to
read the meter to +/- 0.1V.

Even my most rock bottom multimeters, under $3 each new, are easy to read to 1%. Decent meters do much better.

Also, I coulnd't find where anyone
specified the accuracy required.

If you really want 1% accuracy, maybe a 10.0V precision reference,
such as the TI REF102:
http://www.ti.com/lit/ds/symlink/ref102.pdf
However, there's a problem. The IC requires a V+ of 11.4-36VDC which
will probably require a battery or other power supply.

Hmmm... I sorta blundered across this idea:
http://www.qsl.net/kh6grt/page4/expscale/expscale.htm
It doesn't expand the entire meter scale from 10-15VDC.
Instead, it compresses 0-10V into a small part of the meter scale, and
expands the 10-15V over the rest of the scale. However, it requires
+12v and -12v power.

Nice idea, though I don't expect the op needs it. I'm sure one could design a circuit that can use opamps that are happy on the 10-15v and halve V_in.


NT