For my project i'm building a huge VU Meter to go on the beer pong table. Seams like most people use the LM3915 to do this. Now I want to use about 48 leds per VU Meter Have 2 Rows of 24. Maybe it wil be easier to make 2 seperate Meters? Now to do this can I connect more LM3915's or should I just use one LM3915 and connect the LED's with transistors?

For reference skip to 2:25 this is what I want on the border.
YouTube - Best Beer Pong Table EVER (now taking orders for tables)

It depends on what effect you want. Using one LM3915 would mean at least two LEDs would light per step. If you want each LED to be independently lit based on input you would need no less than 6 LM3915s.

Lighting 2 LEDs per step is fine with me. I think if only 1 lit up per step it would be to big of a range and the top LEDs would never light up.

Originally Posted by bountyhunter

You set the minimum (lowest LED) and highest LED turn on level by adjusting the voltages applied to the LM3915 resistive divider.

Thanks for the info but I think it will be better with just 1 LM3915 and having 2 LEDs light up per step, per meter.

Now can someone help me figure out how to wire the leds up. Im going to have 8 separate meters on this table all running off the same LM3915 so there will be 16 leds running off each output on the LM3915. What is the best way to wire the LEDs up?

Originally Posted by audioguru

Each output of the LM3915 can drive a transistor that can drive 18mA into strings of series'd LEDs, each string needing its own current-limiting resistor.

So would I have to run 4 transistors for each string with 4 leds per string to equal 16 leds per output?

But with this set up it draws 80 mA

OK I gotcha. Thanks for all the help

then have the 3915 drive it, have the LEDs 4 sets of 4 in series wired in parallel?
not sure of amout of loss etc, just thinking off top of head??
If I was building such a table, why not just use a PIC, then control using A/D with a mic inputting the analog signal.
might work??
then program several different patterns as well as the AD. using a rotary switch or ? to designate pattern desired.
just a thought???

get out the DVM