[geeks] 9v battery meter

[Dave McGuire]

On Friday, January 10, 2003, at 03:19 PM, Kurt Huhn wrote:
>>    Oh, I thought I mentioned that...the LM3914 drives 10 LEDs.
>
> After taking a look at a cuple schematics, this looks like the best 
> way for
> me to do what I need.  Now, it appears that you need to power this 
> thing via
> a second battery - for reference voltage, right?  Otherwise you would 
> end up
> with seriously messed-up readings?

   Yup.

>   So to read a 9v battery, I should power
> it with a 9v battery?

   It's been probably fifteen years since I played with one of those, 
but that sounds about right.  Ideally the supply voltage should be a 
tad higher than the highest voltage you want to measure but I'm not 
sure what the input margins are like on the LM3914.

          -Dave

--
Dave McGuire           "She's a cheek pincher.  I have scars."
St. Petersburg, FL                          -Gary Nichols