How to combine two LM3914 to build a 20 LED HDD VU meter

[MacGuy]

Hi everybody,

I'm new to building my own circuits, I want to bulid a HDD vu meter powered by the activity led of my HDD.

I found two projects on Gideontech.com and circuits online.net labeled "digital hdd meter and HD led meter.
Both projects use a LM3914 IC and work fine but are limited to 10 LED's. (please refer to the two schematise attached)

I would need a way to combine multiple LM3914 to ideally get 23 LED channel or 20 channels would be acceptable.

I'm not an expert in programming my own chips so if we could stick to of the shelf solution please.

I believe it should not be difficult to somebody with knowledge and practice with IC circuits to modify the existing layout or redesign a new one.

Thanks you for your help in advance!
MacGuy

 

[FvM]

The basic methods to cascade multiple LM3914 are described in the datasheet.

 

[BradtheRad]

Here are helpful links. The 3914 datasheet gives examples for cascading 2 of them:

**broken link removed**

http://www.electro-tech-online.com/...s-reviews/110441-lm3914-20-led-voltmeter.html