Cheers guys, will get a lm3914 to play with, i've set the circuit up on the breadboard so we'll see if i get some pretty lights up and down with the pot lol!

Stu

 

Just to keep things ship shape and all that sort of thing I corrected an error, added a note for the jumper block, and updated the schematic. So here is the latest for your use

Attached Images

	dotgraph_1.gif (40.3 KB, 6 views)
	dotgraph_2.gif (37.4 KB, 4 views)

__________________
Forget injuries, never forget kindnesses.

 

Cheers Mike

Stu

 

Let us know how it turns out...

__________________
Forget injuries, never forget kindnesses.

 

Oh, and here is a somewhat of a parts list. You need to pick your LEDS. Low current ones I would suggest.
------------------------------------------------------------------------
Qty. Value Ref Des.
1 .01uF C5
2 .1uF C2 C4
1 1.1k R2
2 10k R4
1 10k Pot R5
2 2.2uF C1 C3
1 2.4k R3
1 20k R1
20 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12
D13 D14 D15 D16 D17 D18 D19 D20
1 Molex J1
2 LM3914 U1 U2

For J1 look here.
http://www.molex.com/product/cgrid/5547.html

Can be ordered through Digi-key.

__________________
Forget injuries, never forget kindnesses.

 

Once your happy with the setup of the basic LM3914 circuit
you will be delighted to discover that the chips can be cascaded to produce the desired result that you were looking for originally

__________________
It may seem like a good idea at the time , but never stir your cold coffee with a soldering iron.

 

if you could find a pot you could use a 3916 bargrapg display driver for it.

 

Thanks for all the input guys really appreciate the help.
See the +5v inputs, is that the max voltage a lm3914 will take, as it would have to run off 12v from the car.
I'm such a newb at reading the circuit diagrams

Stu

 

Stu, the datasheet says max 25v supply voltage

Jim

 

Ugh, your correct in your thinking. You want twelve volts, but the circuit I gave was for 5V (Will work at twelve but components values may need to be changed). I kinda assumed you might use a 5v voltage regulator like
http://www.national.com/mpf/LM/LM317.html

The Auto voltage is rather a noisy world and straight 12-14vdc from the auto might cause noise issues in the circuit (Such as sporadic led operation). A regulator would help clean up the standard auto volts.

__________________
Forget injuries, never forget kindnesses.

 

Hi Stu,
I found a PCB in my garage made by Maplin that is basically a 20 LED voltmeter based on 2 x LM3914.. Any use to you??

Jim

 

Hey Jim,
Yes im sure that could prove useful to me, it seems the LM chip i have has been shorted out by my brother when he was trying to build something else.

Stu