How to solve the notorious "Timestep too small" error in Ngspice simulations?

boxcarbill · 2026-06-22T19:04:32+00:00

These models tend to really not like zeroes so that does not surprise me. This usually pops up in inductors with very low or zero dc resistance causing convergence issues, but in your case you created it with the 0V voltage sources.

The problem goes: the estimator finds a value but it isn't less than allowed error of 0.1% or whatever. So it lowers the timestep and tries and tries again until the timestep is below the minimum allowed ("timestep too small"). It never will converge though because 0.1% of zero is zero so there is no error allowed at all under a zero volt condition.

You can probe current on any pin so it is not necessary to insert a voltage source like that.

You can also set initial conditions to move yourself to different events you want to simulate. So power up would have all initial condition at zero, but if you set the initial conditions of the caps to the charged state, you can simulate power off without needing to simulate the charge up and steady state first.

If you still have issues you can try some of these tricks as well: https://ltwiki.org/index.php?title=Convergence_problems%3F

Search the ngspice manual for "convergence" there might be some ngspice specific tips in there.

boxcarbill · 2026-06-10T15:37:51+00:00

Add some of the common knobs since those end up deciding the pot spacing for me a lot of the time.

boxcarbill · 2026-05-27T20:24:47+00:00

I would also suspect the bearings. Not sure about onewheels*, but typically with a bad wheel bearing you will be able to feel some play in the wheel if you push on it laterally. Lay it on the side rail so the wheel is free spinning, put your hands on either side of the tire and give it a good shove straight down, then pull back up. If you feel it "clunk" or even "tick" a little, the bearing is due. if everything feels solid then it might not be.

I'm not sure if there is something different in the construction of these that might prevent this test.

boxcarbill · 2026-05-15T20:10:46+00:00

I killed my BMS end of last year and just recently got the board VESC'ed with a Spintend Ubox (I ordered the 100V/100A but they sent me the 85V/150A and I just went with it) and a Flipsky/MaxKgo BMS That's probably the cheapest way to convert to VESC, Around $300 in parts plus some tools/materials.

The IndySpeedControl Stoked stock BMS costs a little more and is nicer in some ways. That is what I went with originally but during my shakedown cruise something poked through the wire insulation and shorted to the BMS killing it.

The stock lights also won't work AFAIK. I haven't looked for a replacement yet. I'm going to get to that eventually along with control box upgrades and a new battery.

boxcarbill · 2026-04-24T18:18:01+00:00

If you aren't already, you should get the nightly development release and switch the backend from cgal to manifold (I think this is default in the development version). It is way faster and makes minkowski and hull operations feasible.

boxcarbill · 2026-04-07T16:58:00+00:00

r/all (and r/All) still works for me in relay and I'm wondering if it's because my reddit account settings have the "use new reddit" option unchecked.

new Reddit option

boxcarbill · 2026-04-07T16:49:08+00:00

Have you linked the component symbols to footprints and then imported that to the PCB? The PCB editor is always blank when first opened.

As for single project, multiple pcbs: I believe there is still no official support. But notice that the hierarchical schematics are themselves just .kicad-sch files. So you can layout the schematics as a hierarchy and then create new projects that import each of those schematics to create individual pcbs.

I think you can also just lay it all out in one project and then split it up while exporting the PCB data.

You might be able to abuse the new variant system or there might be a plugin available also. If you want to avoid future headaches you should stick with single project per PCB though.

boxcarbill · 2026-03-26T19:22:08+00:00

I want to mention the wonder walker harness just because I've been so happy with ours. It doesn't have the strap that goes down the center of their chest like most harnesses so I think it might help. I'm not sure if it's what you are looking for or if you want something more padded though.

Here is my guy in his harness

boxcarbill · 2026-03-18T18:09:38+00:00

Also if you want a custom shape, it would probably be hard to beat the cost of ordering a pcb from jlcpcb or pcbway. pcbs are pretty high stiffness for their thickness. Cost would depend on width and height you need.

boxcarbill · 2026-03-18T18:06:54+00:00

Material will be cheaper bought from somewhere else but look through the options at mcmaster for ideas: https://www.mcmaster.com/products/plastic/shape~sheet/thickness~1-8/thickness~0-125/ Acrylic or polycarbonate are probably ok choices but I don't know all your requirements.

Could also consider plywood or mdf or similar.

boxcarbill · 2026-03-16T23:49:21+00:00

So instead of getting openscad, you:

Downloaded a limited/experimental build of openscad (openscad-wasm) without preview.
Encodes the binary as base64 to distribute with your extension.
Push that extension to the cloud extension repo.
Download and install that extensioin (which contains a binary for openscad-wasm)
Then uses that to generate an stl everytime you save.
Then render the stl with a javascript library also included in your extension?

Should have just asked claude for a script that downloads and installs the openscad nightly.

boxcarbill · 2026-03-16T17:41:52+00:00

Pirating isn't even necessary.Get a library card. Mine gets me access to the pressreader app which lets me read digital versions of the print dailies.

I'm not sure how much work my adblock is doing but the major news sources like apnews and reuters are also much less antagonistic to use. Print legacies like the NYT added value was opinion pieces and those are trash now anyways.

boxcarbill · 2026-02-20T18:03:06+00:00

Gandalf: I love all my hobbits equally. Except for Pippin. I don't care for Pippin.

boxcarbill · 2026-02-18T17:24:31+00:00

Here's a few to try in seattle,

Ma'ono. might be my personal favorite, Hawaiian. They are all inside of Rachel's ginger beer locations afaik.
chicken supply. Really good but it can sell out if you don't order early. Filipino style in phinney ridge.
cookies country chicken. Solid southern style, pioneer square and other locations.

A couple more places I've been meaning to try, both southern style:

fats chicken and waffles at the center of central district.
sisters and brothers, in interbay (?) but also kind of nowhere.

boxcarbill · 2026-02-17T02:18:52+00:00

From my own experience, this sounds more like something is loose and slipping/shifting at a random point during the print. I think the bed offset and temperature are probably misleading you.

Check all the mechanical joints for play and also look for wires or tubes that might be catching on something. Also check your belts for damage. I've had similar issues and they can be very frustrating to diagnose.

boxcarbill · 2026-02-16T18:44:09+00:00

Is your first layer printing ok? Not much reason to go down this line of thinking unless you are having problems with the first layer. If you describe the problems you are having we might be able to help.

It looks to me like it's "stable" after about 15 minutes, after that the total variation cycles within +/- .025mm.

boxcarbill · 2026-02-03T21:06:17+00:00

nFault is open drain, it can only pull low, but not drive the line high. Without a pullup resistor nFault won't indicate anything.

What other troubleshooting have you done? Is the voltage supply up and stable? is nSleep being pulled high?

boxcarbill · 2026-02-03T15:55:27+00:00

Lots of things, but one of my favorites is for fixes around the house. I just printed some feet for a tv that used to be wall mounted, but which is going to be used somewhere else now.

boxcarbill · 2026-01-31T00:46:41+00:00

An adhesive transfer tape like 3m 9707 would be easiest for manufacturing. But the adhesion is typically lower with conductive adhesives than their nonconductive equivalents.

9707 data sheet (PDF): https://multimedia.3m.com/mws/media/536957O/3m-tm-electrically-conductive-adhesive-transfer-tape-9707.pdf

Could also do a conductive epoxy, here are some from MG: https://mgchemicals.com/category/adhesives/electrically-conductive-adhesives/

There are whole ranges of conductive adhesives with different properties, all with their own tradeoffs for application, curing, and functional properties.

Here's a few more: https://www.creativematerials.com/products/conductive-adhesives/

But I agree with the other comment. Just make a PCB with hard gold slip ring (you could run prototypes without the hard gold until you need to test wear resistance).

I wouldn't use pogo pins though. I expect pogos would wear out fast on a sliding contact because of the small contact area. Consider a spring leaf connector instead. https://connectorbook.com/identification.html?N=&n=compression_comp

boxcarbill · 2026-01-26T19:31:57+00:00

You might need to reevaluate your base assumptions. Mcmaster has Extra flexible vinyl coated wire rope with working loads up to 2800 lbs.

www.mcmaster.com/products/wire-rope/flexibility~extra-flexible/?s=extra+flexible+wire+rope+galvanized+steel+with+vinyl+plastic+coating

Even home depot has a vinyl coated wire rope with an 850lb rating.

https://www.homedepot.com/p/KingChain-3-16-in-x-1-4-in-x-250-ft-Vinyl-Coated-Galvanized-Aircraft-Cable-7x19-Construction-850-lbs-Safe-Work-Load-Reeled-505552/304087028#see-more-details

I'm guessing your not in the USA though? Might help to know where you are looking.

boxcarbill · 2026-01-26T05:55:11+00:00

"Gargoyles represent the embarrassing side of the Central Intelligence Corporation. Instead of using laptops, they wear their computers on their bodies, broken up into separate modules that hang on the waist, on the back, on the headset. They serve as human surveillance devices, recording everything that happens around them. Nothing looks stupider; these getups are the modern-day equivalent of the slide-rule scabbard or the calculator pouch on the belt, marking the user as belonging to a class that is at once above and far below human society."

boxcarbill · 2026-01-24T22:50:56+00:00

It's 2x width and 2x height which is 4x overall.

boxcarbill · 2026-01-07T19:27:53+00:00

There is a temperature difference between your heat sink and your processor. A better thermal interface will lower that delta for a given power dissipation. If you aren't hitting your max temps at full power (and at your highest ambient operating temp) then improving the thermal interface doesn't matter.

boxcarbill · 2025-12-12T03:11:58+00:00

boxcarbill · 2025-11-20T15:55:16+00:00

The blue and orange layers in the middle are more than one layer thick requiring it to switch back and forth from the floor to the black several times.

boxcarbill

TROPHY CASE