Working with a new kit for the 5×5 graphic eq

As you can see below, I have decided to change the board that will be driving the large 6’x4′ 5×5 display.

On the original board the LM3915 is getting crazy hot with different LEDs in there and I really don’t want to add more components to the mix. There is a current limiter on the LM3915 and without using transistors and changing things up quite a bit more, it just won’t fit my needs.

I ran a test last night using the 100-120ma LEDs on the CanaKit CK109 – 3-Channel / 15-LED Audio Spectrum Display / VU-Meter (Electronic Kit – Requires Assembly). and it worked out pretty well.

I am sure I am overloading something as I just swapped the LEDs. I have an event I will be attending in about a month, so I am really hoping to have something ready for the event.

I will take some pictures tonight, since I forgot last night. The display is fairly large.

For now I am holding off on the board with the LM3915. Until I can learn a little more about providing more power and grounding without overheating the LM3915, it will be on the back burner. (unless this new board I can’t get 5 frequencies out of)

The great thing about the LM3915 is the huge display that reacts very well to music. I will probably make a wall version of it in the future without getting rid of any of the bands or LEDs.

So for now I am looking to add 2 more bands to the CanaKit board or using my 2nd kit and change the frequencies a little. Now that shouldn’t be too difficult. I wish I brought the info sheet and schematic to work, but I will put it up this evening as well if anyone wants to take a look at it.

Looks like the main differences are the caps used to split the bands. You can see photos of the schematic and parts for the CK109 kit below.

Band 1 uses a .047 prior to going in to the LM3900 and another .047 that goes around and meets up on the output.
Band 2 uses a .012 before going in and another to the output.
Band 3 uses a .001 prior to going in and a .0022 that goes to the output.

So I wonder if I change the caps to somewhere around .006 for a new band and 2 .024 on the other if that will give me 2 more near the middle. Then I can use 2 of these kits to provide the 5 different bands I need.

I am going to put it together over the weekend and see how it turns out. At least it is driving the higher power LEDs without any problems, I might even be able to make them a little stronger when I get the proper resistors on the LEDs. But even the way it is, it will be sufficient to power the large display.