I have modified the new Lego Star Trek Enterprise D model to incorporate led lighting. All wiring is internal to the model and given the obvious space/size restrictions in modifying something that was not made to be modified, I have used:
WS2812B 2.7mm Ultra Narrow led strips
3-conductor twisted 32 gauge stranded wire for the internal wiring
Arduino Mega 2356 for control
This is a description of each strip and the number of leds in the strip.
-Nacelles LEDS
port 63
starboard 59
-Formation
port nacelle ventral 1
starboard nacelle ventral 1
secondary hull ventral 1
port saucer dorsal 3
port saucer ventral 3
starboard saucer dorsal 3
starboard saucer ventral 3
bow saucer dorsal 3
bow saucer ventral 3
-Thrusters
port saucer rear thruster 3
port saucer forward thruster 3
starboard saucer rear thruster 3
starboard saucer forward thruster 3
-Impulse engines
starboard saucer impulse 4
port saucer impulse 4
secondary hull impulse 4
-Shuttle bay 2
-Bridge 12
-Phasers
port secondary hull dorsal 2
port secondary hull ventral 2
starboard secondary hull dorsal 2
starboard secondary hull ventral 2
saucer dorsal ring 137
saucer ventral ring 76
total leds 402
Each “segment” is its own led strip wired separately which means 78 wires coming out the bottom of the model (26 segments x 3 wires/segments).
Each individual segment has been successfully tested/animated using the Mega and a breadboard with its own 5V 700mA power supply.
What I believe to be power supply problems (led flickering, segments suddenly not working at all) occur when starting to combine the segments into one large “circuit” (for lack of a better term).
The Mega and breadboard power supplies are grounded together with all segments. I have done some investigation and found I need at least 20-30A.
Assuming this correct, I’m having some trouble trying to design/build the over “circuit”!
Any guidance/suggestions would be greatly appreciated.
I had not considered wire heating as a problem given the model, once full working, would only be "on" for only short periods of time. I will definately now watch for any indication of over heating!!
ABS begins to soften around 105C. And you're going to have a sealed airspace inside where the only way for the heat to escape is by heating up the plastic. I'd suggest a fan. Or better, rethinking your lighting requirements and knocking a decimal place off those current numbers.
If the same power is going into an enclosed space, it doesn't matter if you use one wire or 100 wires. The same power still has to be dissipated from that enclosed space.
Just suppose that you don't go full brightness on the leds? If the model is not in a bright room/spot then 5mA is plenty for an indicator light/ship window.
PS -- oh... wait... 122 (?) leds into 700mA is < 6 mA.
I see that there could be many small groups of leds with V and GND going to nice thick bus cables or metal structural members and the signal wires to a controller... that can treat them as fewer strings connected to each other. Data and Power here can separate. A flatter and smaller controller with probably run 8+ times faster and still program with Arduino IDE. ESP and Pi PICO cost sandwich money and run dual cores! Mega2560 is kind of a big board to embed.
Can you put fans in the model? Blow air throughout. 700 mA isn't that much if it can't build up.
If it had sufficient thin metal skin area, that would double as a heat sink if outside air is cool and or blowing over it. Plastic tends to insulate. Use paint remover and fine steel wool to clear the paint off an aluminum can, they are plated underneath usually shiny to reflect and make the paint "pop". Think about incorporating that if you have thermal problems.
Thanks for all the input so far!!! Must appreciated.
My initial description was far for being clear.
Wiring to the strips is internal to the model but the Mega board, breadboard and power supply are located outside the model will be built into a new base.
I have modified many other models to included leds using many UNOs and NANOs and have programmed hundreds of lines of Arduino code. But nothing of this size and complexity (eg progamming the ring phasers). A little weak on electronics, circuit design, etc. other than the basics.
just curious why you did not wire those in series to reduce the number of cables ?
as @GoForSmoke said, don't make them full bright, set the luminosity to an as low as possible number and see what it looks like. Also if you need "white" and not another color, there are WS2811 LED Strip 5050 with, single color pixel and the power consumption is lower than an RGB strip driven to produce the same white, because only one emitter per pixel is lit rather than three. (I 'dont know if they exist in super thin versions)
I've seen models also where they used only one bright RGB or non RGB led and diffusing materials (like opal acrylic or translucent polypropylene - or even a few layers of baking paper for a quick prototype) âžś an addressable strip gives you per-pixel control so you can create spatial effects (chases, gradients, individual points of light). But if all you actually want is a uniform glow over an area, that per-pixel control is wasted, and you're paying for it in cost, wiring complexity, and many small heat sources. A single LED plus a diffuser achieves uniform white more simply and you also concentrate the heat into one component, so if needed you can add a an aluminum substrate or a small heatsink right under the led.
With the total LEDs being 402, that is not all that much. The Strip you are using, is it the type with 2812C 2020 LEDs or the 2812B 5050 LEDs ? because they have different power requirements.
Are you daisy chaining strips or sending signal using individual pins of the mega ?
The longest strip is 137 LEDs, How many LEDs per meter ?
How far away is the PSU and the Mega going to be ?
Indeed, based on 60 mA per point, you need approximately 25 A.
However, taking into account fill and partial brightness, 40-60% of the maximum is usually accepted, so a reasonable compromise would be to use a power supply rated for approximately 10-15 A.
It is important that the strips be powered separately (not via the Arduino board) and that the voltage matches the strip's specifications. Avoid intermediate converters, and certainly don't power your entire setup via the Arduino's VIN pin.
Wiring in series - modifing the model to keep the wires out of sight was difficult at best. Wiring in series would have required establishing paths through parts of the model that where difficult to access, difficult to find channels through or around and then re-assemble. All the areas of the model (except for the nacelles and ring phasers) where leds are located are very restricted to access and available free space. Next time, adding leds maybe easier while the building the model vs after assembly.
the leds are 2.7mm WS2812B 160/m for individual control and effect - the longest segment is 137 leds (saucer dorsal ring phaser) and shortest is only 1 led.
the brightest segments are those in the nacelles (the long nacelle cooler segment is blue and bussard segment is red). Each segment has a brightness level of 200.
the formation led segments are white and strobe from a normal brightness of 10 to a flash of 170. None of the segments are set to full bright.
as mentioned, trying to light the entire model with the breadboard power supply resulted in constant flickering and reduced brightnes in segments that did light.
all the segment wires are approx. 30 inches (76 cm) in length.
the PSU and Mega are approx. 12 inches (30 cm) from the base
Can you show a link to where you got them from. Or the bag it came in should tell you how many Watts per meter.
So that is still less than a meter.
I don't know what cable type you used for power, but for the short sections nothing thick should be required.
Best is still to connect all 5V+ & GND at the earliest chance and run a decent bit of cable to the PSU frm the LEDs and power the Mega from this same PSU (to the 5v pin) with some decent cable.
From the mega to the Din of each individual segment, make sure there is a current limiting resistor on the Mega GPIO pin and you can use thin wire to get to the LED strips.
Probably best to start with the longer strands first and add them one at a time and make sure you power down the whole thing while connecting new wires.
So all together about a meter away, should be fine.
You could have had every strip with a return wire from the last Dout back to it's point of origin and from there to the next bit of strip, now you have to multi-channel it all which requires all of those extra pins and as a result a bit more bulky MCU, but it should all work. (please post the code you have so far (within <code> tags)
Tell me this isn't the case for the feed wires to the longer strings. The current to run those strings will exceed the current rating for 32 ga wire. For 32 ga wire, I wouldn't run more than 1/3 ampere; your voltage drop for 1 meter of wire at that current may still be excessive(but I think not, 132 milliohm*.333 is only 45mV)), which will cause flicker and dropouts regardless of how well you wire the external circuit. (Ampacity of wire here:
Not surprised, running any significant portion of 25 A through a breadboard should have smoked a few connections, but your breadboard power supply went into overload shutdown to save itself - which is to be expected, given it's a 5V 700mA power supply. Be glad it did.
Different code would let you get away with fewer data pins by organizing the lights into fewer strips. A single 328P can run 100's of leds whether on strips or a singles wired to shift registers.
If that includes power, you just jacked the required Amps going through the strips.
If that's data only, no problem since the strip uses supplied power to move data bits.
Power and data for led strips can be separated, not a problem as long as the strip has power. Thick wires (less resistance) for +V and GND can deliver power to many sections with thinner wire and less Amps. Power and signal are separate concerns, they don't have to stay together.
