Beware. I had Claude code with opus building boards and using spice simulations. It completely hallucinated the capabilities of the board and made some pretty crazy claims like I had just stumbled onto the secret hardware billion dollar project that every home needed.
None of the boards worked and I had to just do the project in codex. Opus seemed too busy congratulating itself to realize it produced gibberish.
ZihangZ 18 hours ago [-]
This matches what I've seen too — the hallucination gets much worse when the loop has no external verifier. "Does this board work?" has no ground truth inside the model, so it defaults to optimistic narration.
What OP is doing here is actually the mitigation: SPICE + scope readout is a verifier the model can't talk its way past. The netlist either simulates or it doesn't, the waveform either matches or it doesn't. That closes the feedback loop the same way tests close it for code.
The failure mode that remains, in my experience, is a layer down: when the verifier itself errors out (SPICE convergence failure, missing model card, wrong .include path), the agent burns turns "reasoning" about environment errors it has seen a hundred times.That's where most of the token budget actually goes, not the design work.
jddj 18 hours ago [-]
What throws me about this comment is the missing space between the period and the T in the last sentence.
Did the model itself do that? Was it a paste error?
svnt 14 hours ago [-]
I’ve also noticed Gemini and Claude occasionally mixing terms recently (eg revel vs reveal) and can’t decide whether it is due to cost optimization effects or some attempt to seem more human.
I can’t recall either using a wrong word prior this month for some time.
lambda 14 hours ago [-]
Or just because mistakes are part of the distribution that it's trained on? Usually the averaging effect of LLMs and top-k selection provides some pressure against this, but occasionally some mistake like this might rise up in probability just enough to make the cutoff and get hit by chance.
I wouldn't really ascribe it to any "attempt to seem more human" when "nondeterministic machine trained on lots of dirty data" is right there.
svnt 14 hours ago [-]
Sure, but if that were the case why has it gotten worse recently? I would expect it to be as a result of cost optimization or tradeoffs in the model. I suppose it could be an indicator of the exhaustion of high quality training data or model architecture limitation. But this specific example, revel vs reveal, is almost like going back to GPT-2 reddit errors.
I also don’t want to pretend there is no incentive for AI to seem more human by including the occasional easily recognized error.
lambda 13 hours ago [-]
Or just the models are getting bigger and better at representing the long tail of the distribution. Previously errors like this would get averaged away more often; now they are capable of modelling more variation, and so are picking up on more of these kinds of errors.
svnt 10 hours ago [-]
That makes sense, but what is the solution?
jddj 13 hours ago [-]
Looking at the account's other comment there are subtle grammatical errors in that one too.
Would be good to see the prompt out of morbid curiosity
_fizz_buzz_ 1 days ago [-]
I haven't tried it with codex yet. But my approach is currently a little bit different. I draw the circuit myself, which I am usually faster at than describing the circuit in plain english. And then I give claude the spice netlist as my prompt. The biggest help for me is that I (and Claude) can very quickly verify that my spice model and my hardware are doing the same thing. And for embedded programming, Claude automatically gets feedback from the scope and can correct itself. I do want to try out other models. But it is true, Claude does like to congratulate itself ;)
ezst 19 hours ago [-]
It's because you are holding it wrong!
--courtesy for all the LLM pushers so they don't have to bother commenting on this one
varispeed 17 hours ago [-]
This week I tried to use Opus to analyse output from an oscilloscope and it was impossible to complete, because Python scripts (Opus wrote itself) were flagged for cyber security risk. Baffling.
Eextra953 15 hours ago [-]
Nice scope!
I had a similar experience with using Claude to automate circuit design/simulation/optimization and found that they are not good at it.
They are surprisingly good at taking raw files and describing what is in them, but they fall apart when trying to do anything other than design the simplest circuit. I think it is because they have no concept of the physics behind a circuit, so they cannot make changes that a designer would make. For optimizing a circuit using, say, an EM simulator, they don't know what to tweak and how to tweak it. In the end, I had to write a script to talk to the simulator and create a config file that specified the bounds of the simulation: step size, optimization algorithm, min, max, etc. Only then could I use an agent to call the script to optimize the circuit.
_fizz_buzz_ 15 hours ago [-]
Yeah, taking the spice list as the starting point works much better, imo. I also prepopulate the CLAUDE.md file with some information like the pinout/pinmux of the MCU otherwise claude might run in circles trying targeting the wrong pin (to be fair that also happens to me, lol).
andrewklofas 1 days ago [-]
Hit this exact wall six months back building Claude Code stuff for KiCad review[1]. First pass let Claude read .kicad_sch directly via grep/read. It happily invented pin numbers that didn't exist. Rewrote it with Python analyzers that spit out JSON, now Claude just reads the JSON, problem mostly went away.
Curious how spicelib-mcp handles models that aren't in the bundled library. Do you pass the .lib path as a tool arg, or does the server own a registry?
Spicelib really just makes calls to the selected spice engine (in my case ngspice). In this setup spicelib‘s main job is to parse the raw spice data and have a unified interface regardless which spice engine is selected. But to answer the question: the path to the spice model must currently be set explicitly.
jLaForest 15 hours ago [-]
very cool, im working on a similar kicad tool for dong the fully schematic generation and pcb layout using python generated by AI. Not quite ready to publish it yet, but im glad im not the only one who sees the potential of AI generated code + kicad
foreman_ 23 hours ago [-]
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Scene_Cast2 1 days ago [-]
I've found that having LLMs work with mermaid diagrams makes describing and modifying circuits less annoying.
skyberrys 15 hours ago [-]
This is an interesting use case with Claude. It sounds like you took away some tedious work with the checking of waveforms, and you are able to speed up your design loop because of it.
walski 21 hours ago [-]
> SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose, open-source analog electronic circuit simulator. [1]
Nice! Doing something similar with a Jumperless so that the model can reconfigure the circuit on the fly.
_fizz_buzz_ 1 days ago [-]
Oh, I remember seeing Jumperless a while ago, but completely forgot about. Combining this with something like Jumperless does sound interesting. What does your setup look like? Does Claude tell you: "try 1k resistor in parallel here"?
Archit3ch 1 days ago [-]
It's just measurements for now. But sourcing ideas from the model could be interesting!
Schlagbohrer 21 hours ago [-]
Great use case!
dharma1 20 hours ago [-]
this kind of thing is super cool to close the loop.
waiting for FPAA to get better so we can vibecode analog circuits
Really nice. My mother is an applied Physics teacher, and she told me they had a hard time at work figuring out how they could connect their teaching material to LLM in a relevant way. This should be useful to her.
hulitu 1 days ago [-]
Measure with a micrometer, mark with a pencil, cut with an axe.
hexo 21 hours ago [-]
Heh, this is like the last thing you need claude for. I mean, you have eyes and brain.
mystraline 13 hours ago [-]
Can we start pivoting to local LLM integration rather than choosing a service that has something like 5 rug-pulls?
Ye'ol poop splatter (Claude) is getting worse, more expensive, and anti-user. Local may be slower, but it is where the future of LLMs are going to.
pixelsort 13 hours ago [-]
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alex1sa 23 hours ago [-]
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redoh 20 hours ago [-]
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yashjadhav2102 20 hours ago [-]
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strimoza 19 hours ago [-]
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vomayank 1 days ago [-]
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_fizz_buzz_ 1 days ago [-]
Claude can absolutely correct itself and change the source code on the MCU and adapt. However, it also does make mistakes, such as claiming it matched the simulation when it obviously didn't. Or it might make dubious decisions e.g. bit bang a pin instead of using the dedicated uart subsystem. So, I don't let it build completely by itself.
vomayank 7 hours ago [-]
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pukaworks 13 hours ago [-]
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Rendered at 05:51:28 GMT+0000 (UTC) with Wasmer Edge.
None of the boards worked and I had to just do the project in codex. Opus seemed too busy congratulating itself to realize it produced gibberish.
What OP is doing here is actually the mitigation: SPICE + scope readout is a verifier the model can't talk its way past. The netlist either simulates or it doesn't, the waveform either matches or it doesn't. That closes the feedback loop the same way tests close it for code.
The failure mode that remains, in my experience, is a layer down: when the verifier itself errors out (SPICE convergence failure, missing model card, wrong .include path), the agent burns turns "reasoning" about environment errors it has seen a hundred times.That's where most of the token budget actually goes, not the design work.
Did the model itself do that? Was it a paste error?
I can’t recall either using a wrong word prior this month for some time.
I wouldn't really ascribe it to any "attempt to seem more human" when "nondeterministic machine trained on lots of dirty data" is right there.
I also don’t want to pretend there is no incentive for AI to seem more human by including the occasional easily recognized error.
Would be good to see the prompt out of morbid curiosity
--courtesy for all the LLM pushers so they don't have to bother commenting on this one
Curious how spicelib-mcp handles models that aren't in the bundled library. Do you pass the .lib path as a tool arg, or does the server own a registry?
[1] https://github.com/aklofas/kicad-happy
1: https://en.wikipedia.org/wiki/SPICE
waiting for FPAA to get better so we can vibecode analog circuits
https://www.eetimes.com/podcasts/making-analog-chip-designs-...
Ye'ol poop splatter (Claude) is getting worse, more expensive, and anti-user. Local may be slower, but it is where the future of LLMs are going to.