12V LED voltmeter

[BT Humble]

Been a long time coming, but here it is.  First, a not-very-good picture of the finished article, with the prototype beside it:

The parts list is:

• 4 x BC547 transistors;
  
• 6 x 1N4004 diodes;
  
• 1 x 560 ohm resistor;
  
• 1 x 820 ohm resistor (R1);
  
• 4 x 1K ohm resistors;
  
• 2 x 8.2K ohm resistors;
  
• 2 x 10K ohm resistors;
  
• 1 x 1K ohm mini horizontal trimpot;
  
• 1 x 9.1V Zener diode;
  
• 1 x 5mm red LED;
  
• 3 x 5mm green LED;
  
• 1 x 5mm yellow LED.
  
  

Here's the schematic:

The PCB artwork:

...and the component overlay:

It's pretty much self explanatory, once built you use the trimpot to set the voltage at which the green lights start to come on (I usually use about 12.1V).

Enjoy!

BTH

[wing]

Nice pictures of a white cat in a snow storm! - nothing else.

Stu

North Wales

[Norm]

I get nice clear pictures.

     Norm.

[Norm]

  Looks like a good project after I get thru rewinding a few blower motor armatures.

  Got it saved on my shortcuts disk...

    Thanks...

           ( :>) Norm

[jimjjnn]

Pictures ok here too

[picmacmillan]

there must really be a cat cuz i can see them too.... thanks for the schematic...pickster

[wooferhound]

What is the voltage range from the low LED to the High LED

I have been looking for a circuit like this that would read from 10vdc to 15vdc

And about the pictures. I viewed this story this morning and the JPG images were blank squares filled with white while the GIF images displayed fine. Now it is 2 hours later and everything is perfectly OK.

Guess I was good to the God of Electrons . . .

[Galagedara]

Hay Humble,

I thank you so much trying to help giving your experiments to the benifit of others! Irespective of some sad comments. I could say your diagram is fairly OK to read. May be for some people its a bit of a proble, The printed circuit lay out is no problem. As some one said you may please give the range of the Volt meter. Keep up the good work Humle!

Kind Regards!

Leonard.

[BT Humble]

The voltage range is from 12V to 15.5V or so.  If you need a wider range you can replace the wire links with extra diodes (0.3V extra for each one you add, due to the voltage divider).

BTH

[BT Humble]

Sorry about the pictures everyone, I created them with an old version of Paint Shop Pro and for some reason it created a GIF file that Internet Explorer wouldn't display properly.  I only discovered that after I'd uploaded the pics, so if you 've had trouble perhaps you could try reloading the page?

BTH