DIYbanter - View Single Post - Analogue moving coil meter range extension?

mike[_22_]

On 9/24/2017 6:05 PM, wrote:
On Monday, 25 September 2017 01:53:43 UTC+1, mike wrote:
On 9/24/2017 6:31 AM, tabbypurr wrote:
On Sunday, 24 September 2017 12:06:45 UTC+1, mike wrote:

A series zener needs to draw ZERO current at 10V and still
be 10V at MUCH higher current ratio. You will have to live
with some amount of nonlinearity.

In fact you could re-zero the meter so it reads 10v spot on. Add an extra mark for where it points when unpowered so you can see if it ever decalibrates.

Yes, you can , but it's still nonlinear.
It's a matter of how much nonlinearity you can tolerate.
It's my assertion that the measured quantity is so crude that you don't
need to worry much about anything. Just learn what it reads and calibrate
your expectations to match.

You could stack an AA-cell or two on top of your battery system
and alleviate that problem.

yuck. 2 resistors beats 2 cells any day.
Can't argue with that assertion, but, if you can
provide a circuit that is precisely linear and accurate over the WHOLE
range using
two resistors, I'd like to see it. I'm betting it's more than two
resistors.

What I meant is divide the input to your opamp

Thereyougo...opamp is a lot more complex than two resistors...or a couple
of AA cells.

so it's away from the rails and you don't need any rail boosting.

NT