[Amps] What's wrong here- dropping resistor for DC meter?

[Dr. David Kirkby]

On 07/ 9/11 01:06 PM, Ed Heimbach wrote:
>   Want to meter HV out. Power supply variable from 0 through 4.5 kv dc
>   Have 1 through 5 v DC movement.
>   I built dropping resistor string to multiply meter by 1000X.
>   Meter now has a non-linear response.
>   I.E., 1 volt position corresponds to 1000 volts, 3.25 volt on meter scale  equals 4.5kv.
>
> It would be nice if my max. volts (4.5 k) corresponded with the 4.5 mark on the scale card.
>
>   Easy way out would be to  jiggle resistor values to get mid point on scale (2.5 volts) to correspond with 2.5 kv, and then make new meter scale to agree with indicating needle.
>
>   Any better solutions?
>
> 73 ab3ht

There's no reason what you have done should be non-linear.

Perhaps there's a diode been put in the meter to prevent damage due to 
overvoltage. That could clamp the range. It's a bit silly, as its already 
clamping. A more sensible thing would be a 7 V zener if someone wanted to stop 
damage.


-- 
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?