# Birthday Cake with working LEDS - assistance on how to hook it up

#### Edasher06

Joined Mar 4, 2013
18
Hi All,

Although I usually pick up on things pretty fast, I am VERY new to electronics. This will be my first real project. I am in the process of making a birthday cake CakeBoss style, for my daughters 7th bday party. It will be a singing Barbie on a stage, with stage lights that connect to a Music IR controller so they turn on and off with the music. My biggest issue to tackle is that while MOST people who use Music IR controllers hook them up to a store bought LED strand, and I need a custom strain of LEDs, so I can fit them into the stage light fixtures on the lighting truss. Attached is a picture (I know, I know, it's a terrible pic, I was in a hurry) of what the lighting truss will looks like.

The colored dots in the pic are going to be the LEDS. The Black dots stand for clear white LEDS. I've been researching how to make a custom strain of LEDs, and have been gathering info on how many I can connect together based on the color, what size resistor to use, etc. I was hoping someone with more experience could give me the schematics on how to hook this up, as well as any advice and warnings of what to do/not to do. My final question is for the Music IR controller. For the store bought LED strand,there is 4 wires to attach that hook to the slots on the Music IR Controller labeled RBG+( which I'm assuming must be ground?) so what? There's only 1 ground for all colors in a store bought strand? How would I do this with the custom strand? I also attached pictures of the Music IR controller and a schematic of a store bought LED strand, because I need it to be similar enough to this so I can plug it into the Music IR Controller.

Any help would be appreciated! Thanks!

Alright, apparently I can only attach 1 pic, so I included te custom LED setup. You'll have to look at the store bought LEd strand and Music IR controller on your own, although there is a partial pic of it at the top of the attached image.

#### Attachments

• 44.3 KB Views: 43
Last edited:

#### elec_mech

Joined Nov 12, 2008
1,500
Welcome to AAC.

Interesting. Well, to be honest, I'm not familar with music IR controllers, so until someone smarter/more experienced/etc. comes along, here is my very brief understanding.

Music IR controllers, at least the first one I found on Google on Amazon, are designed to control strings of RGB LEDs, that is red (R), green (G), and blue (B) LEDs. Each set of three would be closely together so as to appear to be one LED.

Not sure if these are common anode (CA - where all the + sides of the LEDs are connected together) or common cathode (CC - where all the - sides of the LEDs are connected together). Don't know if there is a standard or if it varies from manufacturer to manufacturer.

The controller likely sends out pulses to each LED color which allow for a variety of colors. This would also mean, again if I understand the operation correctly, that you can only get any one color at a time. In other words, each and every LED will be pink, yellow, etc. at any one time.

Based on your picture, it appears you're planning to have a separate red, green, blue, and white LEDs lit at the same time, but maybe not.

What would you like to do? Have the same color given off any one time with the ability to change the color or have multiple colors on at the same time in fixed locations?

If the former, you can use RGB LEDs such as these and connect each lead to the controller. As far as whether you need a CA or CC LED and how to connect it, we would need more info on the controller you have in mind. A link to a website or datasheet would be helpful for the controller and LED strand.

If the latter, you might be able to use a music controller, but if you just want the fixed colors to change brightness with the music, I think there are circuits you can put together for that purpose, likely for less than the cost of the controller (depends of course).

We can easily give advice and even schematics on LEDs and resistors, but the key is how you're going to control them, how many LEDs you want to use, etc. We have to know more about the controller and what you wish to do before we can offer much in the way of schematics.

How long will the music play for? What are going to use to play it, e.g., a home theater sound system, boom box, portable MP3 player, etc.?

Also, how are you planning to power this - batteries, wall plug, etc.?

#### Edasher06

Joined Mar 4, 2013
18
Thanks for the response elec_mech!

I got on my computer instead of my phone to try to get you a more detailed drawing. I think I did a little better this time. I also googled how many LEDs I can string together and what kind of resistors I would need. Again, since I do not have a very good understanding of this topic yet, I may be completely wrong. Let me know what you think once you see the drawing. Here is the website I used to figure it out. http://led.linear1.org/led.wiz

When trying to imagine what this would look like, I saw all 4 RED, 4 GREEN, 4 Blue, and 4 WHITE from the sides of the lighting truss as their own circuits. Therefore, all 4 bulbs of the same color would turn on at one time, then the next color, etc. I was splitting up the top of the truss into sets of 4 and 3 circuits,and they also would be in the rotation. It doesn't HAVE to be this way by any means, just so they blink off and on to kinda look like real stage lights.

The drawing also shows the exact Music IR Controller I have. It has 3 channels, and a hookup for a 5/12V. If I had a choice, battery would be preferred, but if I had to do AC that would be OK too. Haven't figured that out yet either.

As far as is it CA or CC, I'm not really sure. If I had to guess, I'd say it had to be CA since the channels have RBG+ printed on them. If that is the case, my drawing might have the wires backwards... Which would explain one of my questions in my drawing about where to put the neg side.

I also included a pic of an LED Strand, so you can see how it normally hooks to the RGB device. The last question you asked about the music medium, its actually a Barbie doll that sings. (the Music IR controller has a mic on it.) If its easier to plug in an MP3, I could do that too, but I assumed it would work since I had the MIC.

Again, thx for the help. Let me know if you have any more questions.

#### Attachments

• 87.1 KB Views: 32
• 234.1 KB Views: 22
Last edited:

#### elec_mech

Joined Nov 12, 2008
1,500
Hmmm, I have to re-iterate my experience with RGBs and controllers is nil, however . . .

The controller you're planning to use works with RGB LEDs which contain a tiny red, blue, and green LED within them. The controller will allow the LEDs to respond to music, but all the RGB LEDs will be the same color at any one time. If this will suit your needs, you can buy individual CA RGB LEDs such as these and use the resistor values you've selected. Adafruit shows a schematic of an RGB strip here.

If, however, you want individual LED colors in certain locations as you've drawn out, it gets a little tricky. You could connect 3-4 LEDs of each color in series and connect the negative terminal to the corresponding color connector on the controller. The positive terminals of each color would then get tied together and connected to the "+" connector on the controller. I'd refer to the Adafruit link above.

There isn't a good way to connect the white LEDs though - the controller is designed to control red, blue, and green only. To boot, if the controller cycles through any color other than red, green, and blue, you'll see two or more of each LED light up at the same time. I don't think this is what you want.

If you really want to have dedicated colors on in specific locations at different times, you could forgo the music controller and make your own circuit. A CD4017 IC could be used to cycle through the colors. A microphone could be added to the clock input, but it may need some conditioning of some sort. Another thought is to use an LM3915. This is designed to allow LEDs to respond to logarithmic sound (what people hear). You could use it in dot mode and tie certain colors to certain levels. Example, red comes on at high notes, blue on low, green in the middle. Here is a video in bar mode. Here is one using dot mode. White could be hooked up to anything in between or just left on.

The hardest part of this project is figuring out how you want the LEDs to work. If you want to use the controller, then you'll either need to use the RGB strips or connect RGB LEDs (not separate red, green, blue ones). This will sync to the music nicely, but you won't have just white lights overhead, red up top, blue in the middle and green on the bottom. ALL of the lights will be on at the same time and will be the same color at any given moment. This should still look cool.

If you really want white overhead, red on top, etc. and each to come on at different times, a CD4017 is easy to hook up. I'm unsure if or how well it could be sync'd to music though. An LM3915 could do this, but I'm not sure if it responds to how loud the sound is or specific tones/pitches. I suspect the former, so this may or may not work well.

Here's something I might do: use a 555 with a CD4017 to control the stage lights as you've drawn them. Each color will come on for say 1-2 seconds, all colors off for 1-2 seconds, then the next color comes on and the cycle repeats once all colors, including white, have come on. Alternately you could do a "Knight Rider" effect where each color comes on from bottom to top, then top to bottom. Then use an LM3915 in bar mode to drive a half-circle display made of different colored LEDs in a rainbow layout behind the singing Barbie doll. The rainbow will light up from bottom to top in sync with the music. This will give you an idea. The rainbow will be your primary eye-catcher and the stage lights will be the gravy. I can design this if you're interested. Of course, this is more effort than you may want to put into it, so maybe not.

#### Edasher06

Joined Mar 4, 2013
18
Yes please! Ill have to see where I can get parts quick enough to get it all together in 12 days, but I'd like to at least attempt your idea. If not, maybe ill grab an led strand while I'm out for the Plan B.

#### elec_mech

Joined Nov 12, 2008
1,500
12 days would be tough. Once you factor in time to design, buy parts, assemble, troubleshoot, then implement into your final piece, I'd give it 2-4 weeks working at light but steady pace.

If you're game, I can design and test something at home. If successful, I can build a circuit on a cheap board and send it to you if I could just ask for some  to cover the parts. I can move quicker since my wife has allowed me my own electronics lab and I have all of the parts I have in mind handy. I might need to order LEDs, more on that below.

No obligations and I can't absolutely promise to make your deadline, but I'll do my best. Definitely grab some strips as backup.

You could get the red, blue, green and white LEDs and begin setting them up and wiring them. I can draw a wiring schematic for them. Did you want to stick with your last layout of 4 each red, green, blue LEDs and 11 white LEDs?

If so, what pattern would you like them to flash in? Example:
1) bottom white on, rest off
2) white off, green on
3) green off, blue on
4) blue off, red on
5) red off, all top white on
6) repeat

I'll add a pot or two so you can change the on/off speed of the lights on the fly. Here's a video of something similar I did for another member. This was for a police flasher for a model car, but you can see there is a pattern and the rate can be changed.

For the rear display, how big does it need to be roughly? Example, 3" high by 5" wide. Which colors would you like and in which order (from bottom to top)? Once I know, I'll draw something up and post it.

My thought is to have you get and mount the stage LEDs and I'll provide the circuit to connect them to (or you can build that if you'd like - I don't know what experience or materials/tools you have handy) and build the rear display with LEDs and circuit. I plan to put a piece of dark transparent plastic over the display to help hide the unlit ones and focus the lighted ones.

Let me know what you think.

#### elec_mech

Joined Nov 12, 2008
1,500
Attached is a schematic for controlling the stage lights.

#### Attachments

• 175.6 KB Views: 47

#### elec_mech

Joined Nov 12, 2008
1,500
And here is an idea for a rainbow display. Total size is 4" high by 8" wide. You can print this and see if it will work for your planned setup.

#### elec_mech

Joined Nov 12, 2008
1,500
Okay, based on your experience, budget, and most importantly time restraint, I wouldn't recommend doing the circuit portions. This is not to discourage you in the least, but there is a lot to learn and the cost for everything including prototyping supplies can add up quickly. This is not to sway you to pay me either - if you're happy with the music controller, it will still look cool.

That said, let me put together a bill of materials (BOM) over the next day or two for the circuit I posted. I buy nearly everything in some type of quantity, so I'll only put down the reduced quantity price I paid. This will also help to give you an idea for the cost of the other circuit - still need to work on that one. You can then decide if you want to move forward with a custom circuit or use the music controller.

I was thinking you already had the LEDs - this would allow you to set them up while I worked on the circuit and save set up time when you get the circuit. RadioShack does sell some that would work, but they're terribly expensive in my opinion, especially for the quantities you need.

I'd suggest getting one or two LEDs and figuring out how you want to attach them to the stage and the lengths of wires you'll need from wherever you want to place the circuit board. I can prewire everything in advance saving you some time.

I'll try to get you a BOM tomorrow.

#### Edasher06

Joined Mar 4, 2013
18
Sounds good! It sounds so cool I really want to do it, but I do agree it's probably too big of a project for me to take on right now, just starting out and on a timeframe. I'll be looking forward to seeing the BOW tomorrow for both ideas.

#### elec_mech

Joined Nov 12, 2008
1,500
I'm researching a circuit for the rainbow display. I found a few I need to build and test, will try to do that over the next couple of days.

I've put together a BOM for the stage lights circuit including LEDs and wiring. I'd need to know how long you need the wires if you decide to proceed. All and all, about $20. The rainbow display is going to have more parts and a lot more LEDs plus a cover. I would guess close to$40 for that if need something right this minute, but I'll be able to say for certain once I've got a working circuit. I'm going to go ahead and build one for myself for fun and perhaps submit it to the completed projects forum here. If this still sounds like something you're interested in, let me know if the size is okay (4" x 8"). You can print it out on an 8.5" x 11" paper and "see". It is scaled properly.

#### Edasher06

Joined Mar 4, 2013
18
Ok. I'm going to go ahead and say definitely YES on the stage lights, and probably skip the rainbow, just to make it easier/faster/and more cost effective. If you do one for fun I can't wait for you to post it! Besides, I just measured Barbie, and she is 13" tall! so 8"x 4" would mean more black background just to be large enough.

#### Attachments

• 32.4 KB Views: 17

#### Edasher06

Joined Mar 4, 2013
18
Sorry for the delay in the measurements. It was harder than anticipated building the stage. I've got a good head start on it now though. Let's skip the LED encasing for now. I found some black plastic pieces that look pretty realistic to real stage lights. That will work.

I've attached a diagram with the OVERESTIMATE of the wiring measurements. It's a little confusing, but I tried to make it as simple as possible. Let me know if you need anything else.

#### Attachments

• 165.2 KB Views: 26

#### elec_mech

Joined Nov 12, 2008
1,500
I was fighting a bug of some type and didn't get quite as much done as I wanted to this weekend, but I did prototype the vertical light circuit and took a video which can be found here. The speed can be increased even more, I just didn't want to make too big a video file to upload.

The green LED at the bottom shows the speed of the clock but won't be on the circuit I provide (unless you want it). The white LEDs at the top will be controlled independently of the vertical LEDs, so you can have the white LEDs at the top at one speed and the vertical ones at another. If you plan to always keep them at the same speed, I can eliminate the second 555 circuit. The white LEDs at the top would still light up in alternating patterns (one set on, one set off and vice versa), just at the same speed as the vertical LEDs change colors.

I've soldered most of vertical circuit to a board as well. I've ordered the LEDs - I can use the ones in the video, I just don't have many white LEDs. Hope to have those in a day or two.

I found some black plastic pieces that look pretty realistic to real stage lights.
Could you elaborate on this - perhaps a link to a picture of what you have? Just keep in mind the LEDs will come wired which may or may not affect how the pieces go on.

Thank you for the wire lengths. Take a look at the schematic in post #7. I've assumed you're laying the white lights out as shown in your drawing with D1, D3, D5, & D7 above D2, D4, & D6. Is this correct? If yes, my plan was to have D1, D4, & D7 light at the same time and D2, D3, D5, & D6 do the same. Kind of a V-shape of LEDs coming on and off. Does this sound good or would you prefer the top (D1-D3-D5-D7) to come on in one instance and the bottom (D2-D4-D6) to come on in the other? Top and bottom as opposed to the V.

If the V, then I'd need to know the lengths for:
D1-D4
D4-D7
D2-D3
D5-D6

The pairs of LEDs on the sides of the stage will be wired independently of each other, so no need to run wires from column to the other.

#### Edasher06

Joined Mar 4, 2013
18
The extra green led isn't necessary. I think I can get the timing right without it. I like the idea of having the white LEDS flash independently of the vertical ones, so keep that second 555 circuit I guess.

The pairs of LEDs on the sides of the stage will be wired independently of each other, so no need to run wires from column to the other
-I wasn't sure if all 4 of the same color vertical LEDs (2 per column) would be wired together or not. 2 and 2 works also, better probably.

-Yes, you are right about the wiring on the upper white LEDS. Wasn't thinking right when I took the measurements. Sorry. I had been Here are the ones I missed.

D1-D4: 15"
D4-D7: 15"
D2-D3: 18"
D5-D6: 18"

Again, I think I did fine with the OVERESTIMATES.

As far as the LED casings, I've enclosed a couple of pictures. They were pretend lights off of an old broken toy the kids had. I removed them before I threw it away. I have 24 in all. What do you think? Will they work? They actually look pretty similar to a really small spool for thread. They are opened at the back, so as far as I can tell, the LEDs being prewired should be OK. I was thinking of just pushing the LED through the middle, using something like a glue gun to secure it?, finding something to cover the backs, and have both wires coming out of the same spot. Good?

Anything else just let me know.

Also, given the fact that my mail service is slower than most, and UPS has an annoying habit of getting my packages, having them at their office a mile from my house, and then dropping them off at the local post office (so I get them 2-3 days after that), when the time comes, we're probably going to have to look into our options for the most efficient way of getting it to me.

#### Attachments

• 293.1 KB Views: 21
• 266.1 KB Views: 15

#### elec_mech

Joined Nov 12, 2008
1,500
I was thinking of just pushing the LED through the middle, using something like a glue gun to secure it?, finding something to cover the backs, and have both wires coming out of the same spot. Good?
Sounds good. The LEDs are 5mm (~0.197") in diameter. You might get away with cutting some cardboard discs and punching or drilling a hole in the center to fill the gap. Hot glue will work if the diameter of the plastic housing isn't too great.

I'll be hot gluing the wires to the board and possibly the LED leads to add some strain relief.

If you get a chance, I'd love to "see" a picture of the stage lighting fixture. This will just give me a better idea of what you're working with.

Regarding shipping, I'd suggest having this shipped to a place of work where UPS delivers regularly and someone is there to sign for it. If not yourself, perhaps a spouse or friend who can be sure to get it to you in a timely fashion? Just PM me when you have an address.

I've finished the vertical light circuit minus the LED wiring. Still waiting on the LEDs, but I'll try to finish the white light circuit and get the wires cut and soldered to the board tonight. I'll add some small standoffs to help protect the solder side and give you something to fasten to. I'm probably going to use wires from telephone cable which will be small and colored. I'll twist them together where I can so you don't have wires going every which way.

#### Edasher06

Joined Mar 4, 2013
18
ok. Ill send you a pic here in a few. Looks like it's not letting me PM or email you directly for the address.

#### Edasher06

Joined Mar 4, 2013
18
Ok. Sorry bout that. Got the PM sent. Here are the pics. I just want to warn you... it's looking pretty scary and unfinished right now. LOL. I've got a lot of PVC, LED casings, and lots of tape. It's been kind of crazy the last couple of afternoons and I haven't been able to get much done.

BUT... spray painting starts tomorrow afternoon... The background (which now will be just colorful paper background) should be done tomorrow too.

The LED casings are small enough I don't see an issue with using the glue gun. I haven't done it yet because I was thinking it would be easier to secure them AFTER I got the wiring, just to make sure everything fits nicely. I enclosed 1 pic with the 5mm LED I bought at Radio Shack and the encasing, just so you would see the proportion.

It's hard to see with the tape, but I DO have holes for the wiring drilled on the vertical columns. Once they are glued and holding still, I was going to have the wiring come out, go to 1 side, then the other, then back in the same spot. All/most of the wiring will be in the PVC and run under the wooden box (which will also be spray painted black tomorrow).

As far as the horizontal fixtures on top... I'm still working on that. I THOUGHT I would be able to get PVC in less than 1/2" for the top... and have run into some difficulty finding it. (vertical sides are 1/2") Right now, to get you your measurements, straws were used, but the sizes will stay the same.

Give me 24 hours and I'll send you another pic, and even better once the lighting is in place. You won't even recognize it.

#### Attachments

• 293.7 KB Views: 17
• 294 KB Views: 17
• 290.3 KB Views: 24