Voltage monitor for car battery

[Acetronics2]

Hi, Passion

we just had forgotten the reverse diode ( 1N400x) from regulator output to its input ...

to be fully "bullet-proof" ... ( see 78L datasheet ...)

But ... , If some LCD (or LEDs ) are used as a display ( we didn't talk about that ...) , that could make you need a 7805 instead of the 78L05 ( in all cases will improve the 5v ref voltage stability ... see output impedance of the 78L series vs. 78 series ... )

Alain

PS: No, it's not the LCD that will draw current .... but it's backlighting !!!

[Pic_User]

I am still playing with Paint.net to draw the occasional schematic for the forum.
Here is the latest from the circuit committee.
Put a fuse in place of the input resistor. Added the wrap around diode.
I am learning to not put values onto the schematic. Then people can discuss different values and the schematic does not change.
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1918&stc=1&d=118650657 1">
The entire drawing was drawn in the paint.net (freeware) program, anyone have a better way to go?
-Adam-

[Acetronics2]

Hi, Adam

Did you try that : http://www.diptrace.com/downloads/dipfree_en.exe

...

Alain

[mackrackit]

This had a good write up in QST last month but have not tried it yet myself.
http://tinycad.sourceforge.net/index.html