[Boatanchors] [MRCA] Panel Meter Circuit?

[J. Forster]

Gene,

It may not need any external curcuitry.

Try just hooking the meter to a variable voltage supply, and increase it
from zero slowly.

It looks to me like you have a 0 to 6 VDC meter in series with an internal
24 volt Zener diode. (It looks like your 25 V data point is a bit off.)

Best,

-John

================




> Hi all,
>
> I am doing a battery project, installing 28V battery system in a 12V
> vehicle with DC-DC converters and charging circuits, etc.  I want to use
> some traditional round analog meters to monitor voltage and current.  So I
> picked up a nice expanded scale (24V to 30V) panel meter which can be seen
> here:
>
> http://www.w2hx.com/x/1967LRS2/V-Meter.JPG
>
> I guess in my naiveté I assumed that this would read volts directly. Well,
> no such luck!  Here's what I know about the meter. First, its resistance
> reads about 230 ohms. Second, full scale (30V reading) appears to be about
> 360 mA (more precisely, 0.36 A - my ammeter does not have any more
> resolution than hundredths of an amp). It is very hard to measure the low
> end of the scale, perhaps 0 mA.  To the best I could, I measured the
> current that corresponded to each voltage marking on the meter.  Here is
> the result:  http://www.w2hx.com/x/1967LRS2/MeterRange.JPG  It looks
> pretty linear.
>
> First Question is. How do I build a circuit that when attached to my
> battery will show the right voltage?
> Second Question is. Are there expanded scale meters that will read direct
> volts? Or do they all behave in this way?
>
> Thanks!
>
> 73 Eugene W2HX
>
>
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