Help! Interactive LED coffee table.

[Langer]

Hello again all.

I'm taking on yet another project, one I couldn't resist after seeing the video below:


After hunting around on the Evil Mas Scientist Laboratories website I found an example circuit diagram and building instructions.

I was hoping that someone could help me make some sense of the diagram below. Perhaps put it into lamens terms for me. I have a bit of hobbiest level electronics experience, but I've never taken on a project like this before.

Here is the circuit diagram, which I understand for the most part, I was just hoping someone could offer up a wiring diagram to help me better understand.

The project called for 16 of these circuits in a 1-D topology (whatever that means)

They took some pics of the circuit as well - simple enough, I just have a bit on confusion identifying which wires correspond with which:

When complete it should start to look something like this (hopefully I can do a better job of wire management).

Any help that you lot can offer would be a great benefit, I don't have much experience with making my own IC circuits... outside of some basic arduino projects.

Thanks in advance.

[TheMainMan]

Love the cat on the table in the video. That just made my day. I'm afraid that I'm not going to be any help on this one as that looks way outta my league. Good luck though, and if you get it working show us!
TheMainMan

[Langer]

Okay, I've redrawn the diagram to be more user friendly (at least I can understand it better now).
click for big

I have a few questions for the electronic experts among us:
1 - On the Chip there are V+ and V- pins... what voltage do I apply to these when using 15V to power the LEDs?

2 - There is also a demand for a second power source of -15V, what does this mean? How do I get negative voltages?

3 - Can anyone suggest some inexpensive power supply units that can power the +15V, -15v, and the mystery IC voltage pins?

4 - Can anyone see any problems with my diagram, or is it all tickity-boo?

5 - For circuit number 1 in the 16 circuit series, do I simply ignore the "IN FROM NEIGHBORS" section? the same question for the last in the series, do I ignore the "OUT TO NEIGHBORS" output? Or is there something that I need to take into account?

THANKS so much in advance, for helping me realize this vision.

[mtekk]

Well I'll answer the last question as it is the easiest. The out to neighbors and in from neighbors are the connections that you make to the other nodes (connect an out from one node to the in on an adjacent node).

Your diagram looks correct compared to their diagram. I'd guess that the V+ and V- for the opamp probably should be 15V, but better make sure the op amp you are going to use can handle that.

[Langer]

Thanks mate!

To help a bit further here are the specs of the IC's I'll be using:

LF347
Gain Bandwidth: 4 MHz
Channels: 4 Channels
Input OutputType: Vcm to V+, Not R-R Out
Slew Rate: 13 Volts/usec
Supply Min: 8 Volt
Supply Max: 36 Volt
Offset Voltage max, 25C: 10, 5 mV
Supply Current Per Channel: 1.8 mA
PowerWise Rating 2: 450 uA/MHz
Internally trimmed offset voltage: 5 mV max
Low input bias current: 50 pA
Low input noise current: 0.01 pA/SqrtHz
Wide gain bandwidth: 4 MHz
High slew rate: 13 V/µs
Low supply current: 7.2 mA
High input impedance: 1012
Low total harmonic distortion: <=0.02%
Low 1/f noise corner: 50 Hz
Fast settling time to 0.01%: 2 µs

I understand that the to and from neighbors goes to the next node in the series, my question is about the 1st and last nodes. Can i simply leave the in and out -respectively - disconnected. Or is there some kind of termination I need to take into account.

[Langer]

BreeSpree from XtremeSystems has suggested that it be a wall mounted art piece... which I LOVE.

I've decided to make a picture style interactive panel - instead of a table (or perhaps in addition to the table).
I'm thinking of using perforated aluminum with LEDs poking though the holes to accomplish this, detailed in a nice metal frame.

The goal here is to make an interactive picture that will light up when you walk past, and also allow you to stand and play with it.


Slight change as per the suggestions of Mohonri over at [H]ard Forum.

[mtekk]

I'm surprised crazybillybob hasn't chimed in yet.

For connecting to neighbors, I would test it in a circular connection pattern, see if you get any runaway. For terminators, you'd just use a resistor to connect to your circuit's ground. It may take some experimentation/calibration to keep away from 'runaway' problems.

I believe that running at 6v won't do it for the chosen opamp. You need the V+ to be between 8v and 30v and you should have V- equal in magnitude (but opposite in sign).

-John Havlik

[Langer]

Thanks john.

I;m pretty sure you're right about the supply voltage.
I was under the impression that -6 [sum] +6 = 12

Here's another revision, but I'm not sure if the lines to the opamp are correct.

[mtekk]

Your opamp hook ups look correct, assuming their diagram is correct.

[Langer]

*I'm not sure about the power going to the opamp though.