Your math is probably for 100% brightness at white color. Rarely will your lights probably be in that state. You’ll have them doing patterns of colors which means that you’re not using all of that power as many of the LED’s are actually off.

I would recommend using one of your PSUs to do some tests. Hook it up at like 2 or 3 amps and write some code to test it out. You’ll find that it might just work fine for your project. What you would likely see if you’re losing power is that the lights furthest down the line start to get dim or turn the wrong colors.

You can actually cut the strip at say the halfway mark and inject power starting at light 0 and at light 151 and connect the data from light 150 to 151. Data signal will make it all of the way through, but boosting a fresh power line in the middle will help.

Hey, thanks for the info. Your suggestions should work, and I'll definitely test it out. If you bought the LEDs, how bright would you say they are compared to a flashlight at maximum brightness? And yes, my calculations are definitely for 100% brightness, I usually like to have enough buffer in case I would like to add that as a lighting option.

Not nearly as bright as a flashlight. They are spread out and not focused though a lens like a flashlight is. While they are somewhat directional they don’t all point the same direction so the overall effect is not as bright. Especially when you use them in a line over 15 feet or so.

If you had them strung up in an otherwise dark room, you’d be able to come in the room and see your way around, but I don’t think I’d want to look for a contact lens you dropped on the floor.

Try to power from both end

I haven't thought about that. Thanks for the idea. I'll test to see if that helps.

This solution is very good. Using single-color LEDs, I powered 9m from both ends and got about 20% more power.

You don't have to limit this to just the ends. There are suitable solder points along the length of the LED strip, at least every meter. The last time I did this I used #10 wire alongside, with connectors for each tap point. I spent an evening in front of the tv stripping bits from the #10 and soldering all the little connectors.

No idea what the maximum is on the pads, but you really don't need that much power.

I regularly use 5m strips of 300, and 18 amps is overkill for just about anything. It would mean each channel of each node is at the theoretical maximum power draw. Even blindingly bright you are still unlikely to draw that much.

I guess you might want that much if you are looking for intense bright white that hurts your eyes even outside during daylight.

I often do power through USB that by spec has 0.5 amps, with some higher power sources of 5A, 2A, or less. USB power would not give blinding bright white across all 300 all at once, but is plenty for bright color patterns across the entire set.

If you have issues with low power in places, you can put power anywhere on the strip. Endpoints are easy, but applying at 1/4 and 3/4 works well too.

I won't suggest hooking up the entire length just like that. Copper tracing on those strips has resistance, too, and in series, you can almost see the light fading at the end of the strip, even if you can supply the full theorethical current. There is a voltage drop per meter you have to take into account like a regular wire. You might have to include power loss from these resistance and make it a 25A if you want to hook the entire length.

The main question here is, what are you going to use it for? I had past experience with this strip, but power was not an issue as I'm using 1m strips instead of the entire length. I love to supply an ample amount of power to prevent yellowing of LED when it's at full brightness white, where blue suffers the most as it requires more current than red to be powered on. Therefore, I used a 5A DC-DC converter from 12V to power the 1m strip. Looks good even when powered on one end.

On your question for how much current that trace can support without burning out, I have no idea about that.

U must be gay

Dua Lipo?

That's when there's two. Four is her older sister Quatro Lipo.

So hot... When you short them together.

So hot...

Smokin' hot...

And octa lipo is her grandma

That's not a BMS, it's a USB PD trigger board. I have a standard USB cable with the 5v and gnd wires connected to the battery (somehow it handles the 16.8v 2.4a it seems to consume)

FNB48 on Amazon, the listings are constantly popping up and disappearing but shouldn't be more than around £40. Keep in mind that when it triggers PD and other protocols all the ports connected to the vbus will be raised to that voltage, so be careful what you connect.

The BMS is a generic 40A 4s BMS board, I've tested it to automatically cutoff past fully discharged and fully charged so seems fine for my at most 2-3a uses

I've always wanted to add some LiPo's to a couple projects of mine but there's something about batteries that always make me hesitant

Honestly as long as you're careful it should be fine.

Good things to do:

• Only solder for extremely short periods of time

• When building the pack use almost fully discharged cells

• make sure you have a plan for cells about to explode

Just buy some 18650 li-ion cells. They are great, much more robust and easier to pop out and stick in other things

They have their benefits, but if energy density and discharge current are needed li-ions will get destroyed by li-pos.

For high current applications spot welding or custom machined copper brackets will be needed, generic battery holders won't be able to go over a few amps before the springs melt their way out of the holder (even with a 24awg spring bypass it still gets very warm)

18650s can go up to 20A continuous current. Springs blow but leaf connectors can support like 10+ amps

Once again, depends on use case. 18650s that support 20a continuous have much lower capacities than the higher density 10a burst cells (approx 2500mah Vs 3500mah).

Connections that aren't soldered or welded will have a higher resistance resulting in more voltage sag (ie. less usable current when battery is discharging)

The pack I built is a 10000mah 4s, with a similar volume you might be able to create a 4s3p battery out of 3500mah 18650s which could get you 10500mah but you probably couldn't get more than 10a out of it without overheating.

I only have this because I had a bunch of pouch cells lying around and wanted to use them up, and I don't plan on putting it in anything moving (it's probably just going to stay on my desk while I figure out some sort of enclosure for it)

Not doggin your design decisions, just arguing against “if discharge current is what you need lipos blow 18650s out of the water.” I don’t think that is true. I don’t think LiPos necessarily have a higher energy density either, looks like their minimum is above LiIon min but their max is below LiIon max.

IMR18650s are capable of 20A cont (35A pulse) while holding 3100mah. Also not hard to find 18650s capable of 10A cont for 3500mah. LiPos do generally have a higher discharge current but they also generally have a lower capacity. I don’t think the “right choice” is as black and white as you’d expect.

I’d love to actually do some math to find equivalents but unfortunately idk the size of your batteries or the current rating. Can’t easily find any single lipo pouch online rated for more than 1.25A continuous unfortunately

I don't see a compression apparatus to keep them in tip top shape (pouch cells require some compression for optimal performance, unlike cylindrical cells).

Even generic li-po cells?

When I pulled apart the power bank there was minimal compression and in fact had some space left over that was taken up by some foam tape

Even generic ones if you want optimal performance.

No he's talking about Lipo cells. It's true for for both.

For Lipo cells you want 12psi of compression. Too much (above 18psi) is actually worse than no compression though.

But it doesn't really matter unless you're trying to maximize cycle count. Applying compression reduces the capacity lost per cycle, you can get 1000 cycles with less than 10% capacity loss out of Lipo cells this way.

It also reduces internal resistance slightly. But that's about it. It's certainly more trouble than it's worth for something like this.

If only they built phones and laptop batteries like that...

Honestly don't mind the extra bulk for longer battery lifespan

Sorry for late comment. The reason compression is important is because the physical layers the cells are made of are kept better squeezed together and have lower internal resistance.

if this is just for the soldering iron, who cares

Looks like a bomb

Some would say it is

They're actually all cells from the same model power bank, the board kept on failing so I stopped asking the manufacturer for in warranty replacements

There's no point since that would require a higher current BMS and a boost converter

Look at the other images, I connected it to power a Pinecil

Nice job man ! It’s funny i saw your post because I was thinking of doing the same thing ! I’ve got a question for you though, do you need a specific bms if you would have put 2 cells in parallel and did a 4s2p ? Or it doesn’t matter as long as each cell was at the same voltage before soldering them together ? Nice job again !

Cells in parallel will balance each other out, but make sure their voltage is very similar or they will charge/discharge each other at very high currents. When putting cells in series a BMS will balance the voltages between cells by charging the lowest voltage cells with the rest of the pack.

BMS parameters that matter G

1. Voltage accepted. Sometimes just one voltage. Sometimes a range like 8S to 24Sv is supported. Sometimes it will accept multiple chemistries as well (1.5V to 4.5V typical)

2. Output power typically measured in amps. Often times a continuous and burst rating.

Balance current might be important but separate balance boards made with a bunch of caps have taken over. They put energy from high cells into low cells so no waste and no heat.

Fire starter or a boom.

Keep tiny gaps between each cell so it can breath… release heat

Actually there have been tests showing that without airflow small pockets just kinda insulate the air and it does nadda for overall pack temp. RC lipos are compressed together…I don’t know of a lipo that isn’t

Yo man nice usb bomb

What does this go to/ suppose to do?!? Low-key confused this with a bomb when I first saw it lol

If you wanted to there’s a bunch of 4S 100W PD Powerbank boards out there. IP2368 is the only one that truly functions as advertised

I am very tempted, but also planning on trying to get my laptop to take 100W PD as an input (the cheap AliExpress boards seem to fail when the massive surge from when the laptop is plugged in and switch to a random voltage)

Lenovo Slim Tip is quite picky about its input power so it's difficult to bodge it lol

What is that WTF

Austin powers ”I also like to live dangerously.”

I'm designing a high voltage battery powered benchtop power supply for prototyping vacuum tube circuits, I figured I'd go with a retro display to match the tubes! There are existing boost converter designs that would do the trick, but the ones I've seen are too bulky for the enclosure constraints of the project. I'm pretty happy with how this turned out, so now I'm onto the shift register / control side of things.

The IC is a UC3845 current mode SMPS controller, the FET is a FQN1N50C meant for light ballast circuits just like this one. This converter operates in DCM in order to achieve high gain at a maximum duty cycle of 50 percent. I was originally going to use a coupled-inductor boost converter topology operating in critical conduction mode (with a L6565 QR controller), but after some analysis I realized that topology reduces to a regular boost converter when L1 = L2.

Disclaimer for anyone who wants to try something like this: HVDC is no joke, even at low current it will kill you. Be safe!

I used a boost LM3578A with a 100V MOSFET + voltage doubler to generate +/-80V for a 20 digits x 14 segment neon display board (arcade) made by Cherry. They used a bipolar supply so that they can get away with 100V peripheral drivers for the 160V display.

The original HV module was free running has no feedback loop, so it draws more power (2x of mine).

I almost went with a boost + capacitive multiplier topology at first! IIRC there was a Panaplex display based wristwatch design that used a similar converter.

Sometimes this sub reminds me just how little I know... As a noob hobbyist, I don't understand much of what you said . But cool work!!

This stuff can be daunting at first, but don't give up! I'm a hobbyist as well, I just spend a ton of time researching to get a sometimes-tenuous grasp on the topics at hand haha

I'm happy to elaborate or explain further if you have any questions.

Just googled some of the terms, I have a better understanding of what's going on here, I would be interested to see the schematic on this. Definitely want to see the finished product too!

Once, I designed an absolute minimal HV boost circuit to drive neon bulbs. My intent was to build something as tiny as possible, so that I could use a neon bulb in a circuit in a similar manner to how I'd use an LED.

I ditched the multiplier stage because DC only lights up half of the bulb. Instead I ended up making a secondary winding and using a self-oscillating converter topology, which produced AC at an acceptable efficiency of about 70%. Built from SMD devices, it was really, really tiny. Only good for a few hundred uA, but that's all that's needed for an NE-2.

Sounds similar to a ringing choke or Royer oscillator topology, cool idea!

yeah, it was essentially an RCC

HVDC is no joke, even at low current it will kill you. Be safe!

Keep one hand in your pocket at all times when probing. Also, use a shorting stick every time you dig into it...

This is good advice! The way this was designed, the feedback divider also acts as a bleeder, quickly discharging the capacitor once the supply is off. I still won't adjust it or touch it while it's on though, and make sure to discharge it with a screwdriver each time just in case. I also make sure to solder on test points and plug in my probes with the thing turned off.

How high is your input voltage ?

16-21v depending on how much charge is left. It's powered directly by a Milwaukee M18 XC 5Ah battery pack which I believe contains 2 strings of 5 18650 cells.

10Vin is really good output voltage for a boost converter. We are told in uni that we shouldnt excpect more than 3Vin.

It's all about CCM (continuous conduction mode) vs DCM (discontinuous conduction mode) operation! In continuous conduction mode switching happens before the inductor current falls to zero, while in discontinuous mode the current falls to zero well before switching, and in boundary conduction mode switching occurs right at the transition.

Continuous conduction mode is what you typically design for with normal boost converters because it's less noisy, more efficient, and has a much simpler transfer function. However, as you noted, you can only achieve a gain ratio of about 9x at most, and that's if you really push it. In DCM mode, you can achieve much higher gain due to the fact that the DCM gain ratio formula includes frequency, inductance, duty cycle, VIN, and load current terms. This is in contrast with CCM mode, which purely depends on duty cycle and VIN.

Boundary conduction mode is especially nice from a control perspective, but it's a bit funky to design around, because you have to modulate duty cycle and frequency. You also have to prevent runaway frequency increase via a frequency foldback mechanism in practical implementations.

I settled on DCM operation for this application.

Would you mind sharing the schematic?

I don't have anything drawn up at the moment but when this project is done I'll publish schematics for sure 🙂

How are you switching the digits?

NM - I just noticed you aren't because every segment is lit. As these are basically 7 segment nixie tubes, you need suitable high voltage control switching.

I have an old Bally Centaur pinball machine with the Panaplex displays. Nice warm orange glow 😉

I'm either going to use a DS8880 neon driver ic or a tpic6b595 HV open-drain shift register, with anode multiplexing via three p-ch MOSFETs. I'm leaning toward the latter since it is still in production and allows arbitrary patterns to be displayed.

This board will also have an ATTiny85 controlling the logic as an i2c slave to simplify connections between boards.

A nifty thing about this boost controller ic is you can use the 5v vref to power other components (with care to ensure reliable regulation of course), it can supply up to 30ma!

I love all these old style displays!

I haven't seen one of these displays since 1975. Had a lot of burn-in failures as I recall (avionics display- it was the only type that was still visible in direct sunlight). Changing the HV from 225VDC to 170 made a big reliability improvement.

Cool Project. Check this part out, maybe it will help you safely adjust the voltage: https://www.thingiverse.com/thing:5973602

Pretty clever design. I've been wanting to buy a 3D printer, so I'll keep this in mind!

I've never seen a nixie display like this. It's basically a nixie tube but sort of in the style of a VFD?

Pretty much yeah! They were a transitional technology from when LEDs were becoming popular. Check out this attack ad Sperry published to try to discredit LED displays: https://pbs.twimg.com/media/D2ocLQvUgAIU70V.png

They were produced under the Beckman and Babcock names as well. The general term for them is "panaplex" displays. I think Babcock kept manufacturing them until fairly recently.

You can find them on ebay occasionally but they're only getting more expensive with time. Some crazy people out there have figured out how to make DIY displays like these, but it doesn't seem easy.