This is the voltage regulator I built to verify that the design
worked. The LM 3914 is very nice. It seems to be able to do almost
anything you want.

<br>It has a display minimum and display maximum voltage in, which
means that you can range your display from for instance 5 to 12V where
you have your fans. This is done on the green displays. 

<br>It also drives the LED. No need for resistors there. Or rather,
you need one resistor to tell it how to drive the LEDs. 

The connector pins are, in order, ground, 12V and signal. The
brown wire is the display minimum voltage.

<br clear=left><img src=../pics/demo_vumeter.jpeg width=504 height=598><br>