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LED strip power question


mbunjes

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HI, I would like to light the innards of my Voron with two 24V led strips, together 54 led beads. I don't want multi color light shows so I  thought I would power it with my normal LRS-200-24 PSU with just an on-of switch.

Is this PSU up to the task or do I need to use a separate power supply for the LEDS ?

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Since you're asking I'm presuming there's no rating on the strips or model number on the LEDs 😉

Using a Guestimate then each LED will draw around 60mA at full power (let's calll it 100mA for safety) so that'll be 5.4 amps in total and at 24V that's 130W (rounded up).

 Basically that leaves 70W on the power supply for everything else which ain't much. OK, I've over egged it but without precise info about the strip power requirements I'm guessing somewhat. But I think even using the 80% rule to give you some overhead you would probably be better off with a separate power supply.

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Watts, amps, volts are all interrelated so depends on  what you're using as the basis for the calculation. So you're kinda right at the same wattage a higher voltage reduces the amperage for example.  At 12v and 0.3W then the LED is drawing 25mA (a lot less than my guesstimate of 100mA). As I say I'm estimating based on generalisations. There's oodles of factors that govern the power draw of LEDs (design, materials, colour, duty cycle, etc)

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8 minutes ago, mbunjes said:

! mtr (60 leds) 24V 5050 leds use only 15W per meter,

So 625mA for the entire m. In that case then yes, plenty of headroom on the power supply, even factoring in a healthy overhead on that. I was guestinating.on an individual LED at full power, as I say many factors at play (including me typing this response  on a phone) 😄

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@mbunjes  I was looking at the issue that you are.   I want LEDs in the chamber but don't need the color change.  I was planning on using a seperate wall wart or other power supply with a simple on/off switch mounted in the front skirt.

Amps and volts are linear.  120v & 10A is the same as 240v & 5A. 

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I just got done adding 24V lights to my Voron 2.4

On 3/18/2023 at 5:47 AM, mbunjes said:

HI, I would like to light the innards of my Voron with two 24V led strips, together 54 led beads. I don't want multi color light shows so I  thought I would power it with my normal LRS-200-24 PSU with just an on-of switch.

Is this PSU up to the task or do I need to use a separate power supply for the LEDS ?

I just finished some 3D Printed LED light bars on my Voron 2.4 350. Its in my queue to post the design on github.  Goal was was to control glare from overhead chamber lights visible from the front of the printer, simplify wiring & soldering, pieces snap together (mostly) and snap into 2020 with -0- screws.  I can create a separate thread if you are interested in details.

An important consideration is to use COB LED strips and not strips with discrete LED's.  LED's become less efficient the harder they are driven, so COB (chip on board) uses many more LED's but drives them at lower current levels compared to discrete strips.  For 24V, COB's string a number of LEDs in series in 50mm sections.  The side bars use a 350mm COB strip and consume 150mA each. Front and rear bars are 400mm ~172mA each. So 644mA total which is no problem for the supply.  I run them from a PWM output on the MCU, and use Klipper buttons to control/dim. Sticky back Aluminized Mylar is used adjacent to the the COB strip to for a corner reflector.  The side strips also use a snap on grate to eliminate visibility of the COB's when viewed from the front. Camera shows the side bar glare being much brighter than in real life. While the 2.0mm JST connector does get soldered onto the strip, it is held in place by a snap fit printed retaining ring. Because the current is so low, the 26awg PTFE wire for power routing is more than sufficient, and there are snap in corner junction boxes and zero clearance 2020 channel covers.

PXL_20230319_191023708.thumb.jpg.5c2b46891706732a3da3b818b70b1eda.jpgPXL_20230319_190915812.thumb.jpg.8c2d63d3106413a024f07eb7179e063f.jpgPXL_20230319_190735488.thumb.jpg.78f729445983aac4170ef51fa95b4a29.jpgPXL_20230319_190729430.thumb.jpg.6e19304fb8a145a70ed0ec5ca0287c2a.jpg

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Yup.  Let me do a proper gitbhub posting with BOM and assembly instructions. Need to find the latest file versions. There's some stuff that bit me assembling the first one like pre-tinning the pads where the connector solders on before sticking the strip to the reflector print.  The copper was heavily oxidized and needed to be lightly abraded to get the solder to wick.

These were the COB LED's  https://www.amazon.com/gp/product/B0B9SFMZ1L  Max operating temp is listed at 60C so even though hot air is supposed to rise, things are toaster closer to the bed because of the radiant heat.

2.0mm JST's  https://www.amazon.com/gp/product/B01DUC1S7S

metalized tape  https://www.amazon.com/gp/product/B07TYKFS8K

 

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My interior lights are COB strips as well. They're rated at 8 Watts/meter, so already low enough to install without fretting about the power load. But keep in mind also that they're quite bright, so you'll probably want to run them through your controller board on one of the PWM-able lines. That lowers the power consumption even more. The duty cycle of my "full brightness" setting is only 25%.

Edited by GarthSnyder
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9 hours ago, GarthSnyder said:

My interior lights are COB strips as well. They're rated at 8 Watts/meter, so already low enough to install without fretting about the power load. But keep in mind also that they're quite bright, so you'll probably want to run them through your controller board on one of the PWM-able lines. That lowers the power consumption even more. The duty cycle of my "full brightness" setting is only 25%.

Do you notice any flicker?  I'm using HW PWM and even at 100% seeing some, not sure the source.  Need to get a scope on it. What's the max op temp spec of your COBs?  what brand?  Units I picked are spec'ed 10W/m 900 lumens/m; 10.28W/m  measured.

No way I'd run these 100% without the diffusers on the side bars because of the glare.  Maybe I'm getting old, but its 100% for me.  They are very bright, but it's not possible to have too much light. Besides, that's what sunglasses are for.  Advantage is it lights up the whole room. 

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6 hours ago, to-the-nth said:

Do you notice any flicker?  I'm using HW PWM and even at 100% seeing some, not sure the source.  Need to get a scope on it.

Yes, flicker is a potential problem and you'll definitely see it if you only change the duty cycle (which Klipper calls the "value"). However, Klipper also lets you set the cycle_time to raise the flicker rate above the perceptual limit, regardless of what the actual duty cycle/brightness is set to. Mine is set to 0.003, which seems to be about the practical lower limit for my Octopus board. Here's the config:

[output_pin case_leds]
# Upper edge case COB LEDs
pin: PD14
pwm: true
shutdown_value: 1
value: 0.05
cycle_time: 0.003

Configured like this with values ranging from 0.05 to 0.25, I never notice any flicker. I'm sure I could find some if I stood in the right place with the LEDs in the corner of my eye, but in practice it's fine.

I'm using these strips, 24V, 8mm wide, 320 LEDs/m, in Warm White. They're cheap and work fine, although the effective color temperature seems significantly higher (cooler/bluer) to me than the normal Warm White standard. I've had these in about a year and they don't seem to be dimming at all. I don't see any temperature spec, though.

Edited by GarthSnyder
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v2.thumb.jpeg.b034de4db34b213f2134fe9f8558069d.jpegI power two strips of COB LED lighting right off of one of the MCUs and control them with Klipper/Fluidd. You can turn them off and on right inside Fluidd (or what ever GUI you are using). It only about 2 feet of lighting so, not too many mA for the MCU board.

https://www.amazon.com/gp/product/B08KG1LKZ4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B06Y2Z8PST/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

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Remember Ohms Law and you can always calculate it out.  Volts (E) = Amps (I) * Resistance (R). Mix this formula around in any way to solve for what you need. Also, Watts = Volts *Amps. Remember the math and you’ll save yourself pain and suffering associated with doing something like thinking you can plug all those LEDs into a USB port on a raspberry Pi.

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I also used COB strips but wedged it inside the extrusions.  Nothing extra to print. The light path may not be optimal, but enough for me. I have silver insulation on the outside of my machine, and white panels. which also diffuses any light back back into the machine.

Hooked it up to the power supply but used one of those battery charger boards like this one:

https://www.aliexpress.com/item/32924643848.html?spm=a2g0o.order_list.order_list_main.96.3e6418027phVjp

You can step down the current and limit the current - I just use the current limiting function to adjust brightness. I'm also running 48V X/Y motors so the 24V power supply has lots of extra wattage to play with.

If I remember correctly, I have all 4 sides done. to connect each side had to measure the right length of wiring and tuck them in somewhere so they don't get in the way.  One wire goes down one of the extrusions, then along one of the bottom rails and down into electronics bay. There's also the two down the back side, not sure if I did the front extrusions as well.

I used some cable clips to keep wiring in place.

One thing I wish I did was wire in an on/off switch, too lazy to do that now.

(Yes, that last photo show my belt slowly killing itself)

20230331_101355s.jpg

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20230331_101426s.jpg

Edited by scotchtape
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Reporting back. The source of the COB LED flicker seems to have been the Extruder. 

Decreasing the PWM update frequency to 10msec from the recommended 100msec fixed the problem:

 [extruder]

#pwm_cycle_time: 0.100

pwm_cycle_time: 0.010

 

@scotchtape impressive 48V steppers!  Silver insulation looks cool.  Higher R value than std Acrylic?  I was toying with the idea of double pane, but sometimes seeing temps up to 70C from a sensor on the side of the StealthBurner.  Gonna need an over temp air dump with some serious filtering at some point.  Or make top panel out of aluminum and use it as a heat exchanger.  What's the deal with your belt?  Gates?  I've noticed a bit of edge fraying on mine.

 

Off topic, but while I was messing with the config file to fix the flicker, I also remembered seeing the comment to limit max bed power.  Urban legend?  Ran some numbers and there's no way to create enough of a temperature differential to permanently deform the cast aluminum plate with one of our heaters. Can't get enough delta T.  Maybe if you had a rolled plate and relieved some stress? Interested to know if there is science behind this.  I've been running 100% with no issues and map looks pretty darn flat.

##      Adjust Max Power so your heater doesn't warp your bed
##max_power: 0.6
max_power: 1.0

 

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12 minutes ago, VoronManiac said:

Off topic, but while I was messing with the config file to fix the flicker, I also remembered seeing the comment to limit max bed power.  Urban legend?  Ran some numbers and there's no way to create enough of a temperature differential to permanently deform the cast aluminum plate with one of our heaters. Can't get enough delta T.  Maybe if you had a rolled plate and relieved some stress? Interested to know if there is science behind this.  I've been running 100% with no issues and map looks pretty darn flat.

This has been all over the Discord over the last couple of months and the consensus seems to have rapidly shifted towards your same conclusion: there's no reason to limit the bed heater current. I've been running at 100% and don't notice any difference.

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