Community rules
CommonGnd is a science-based forum for high-voltage builders, from someone's very first spark to record-breaking arcs. Two things run through everything here: evidence over opinion, and safety above all. We help each other, we're kind to beginners, and we keep it honest.
New here? Read these once, then come and introduce yourself in Start Here and ask your first question in Beginners. The rules are deliberately short and human. They exist to keep the place safe and useful, not to trip you up.
How we treat each other
Respect: talk like people in a workshop
We're all here because we love the same dangerous, beautiful thing. Criticise the work, not the person: "your grounding scheme will cause racing sparks, here's why" is welcome; "you're an idiot" is not. Mocking beginners for asking a basic question is never allowed; everyone wound their first secondary badly. Assume good faith and give people the benefit of the doubt before you sharpen a reply.
Let the moderators moderate
If you're not a moderator, don't act like one. Don't greet new members by accusing them of not reading the rules, and don't pile on or make people feel unwelcome. If a post is a genuine problem, use the flag button and let a moderator handle it. That's what they're for. Being hostile "in defence of the rules" is itself against the rules.
Asking and posting well
This is a place to learn and to help. A good question gets good answers; a lazy one wastes everyone's time.
Do your own research first
Before you ask, search the forum and the canon. Your question has often been answered already. Don't ask for complete schematics, detailed plans or step-by-step build instructions; ask specific questions that show you've done the reading. A good post says what you're building, what isn't working, what you've already tried and measured, and includes a photo or schematic. "It doesn't work, send me a full DRSSTC design" gets nowhere; "my UD2.7 half-bridge shoot-throughs at 30 kHz, scope shots attached, here's my gate drive" gets help fast.
A machine reads your post before anybody else does
Every post goes through an automatic check first, and it is worth knowing what it wants, because it is not what people usually expect. It is not marking your English or your manners. It is counting whether there is anything specific in there to answer: part numbers, measured values, what the scope showed, what you have already tried and what happened. A post carrying none of that can be held or refused, and a long post is asked for more of it than a short one, because length with nothing in it is the shape spam takes here.
If yours comes back, it is not a verdict on you and not a moderator disliking your question. Add what you measured and post it again. "My coil makes short sparks" cannot be answered by anybody; "48in at 120us, racing past 160us, k measured at 0.14" can be answered in one reply.
Evidence, not opinion: no pseudoscience
This is a science-based technical forum. Hard evidence, measurements and reproducible test results drive discussion, not politics, marketing or personal belief. Free energy, over-unity, perpetual motion, electrogravitics and other pseudoscience are not allowed anywhere on the site, and neither are links to sites that primarily push them. If you genuinely believe you have an exception, you'd better arrive with undeniable, reproducible, independently-checkable proof. Extraordinary claims need extraordinary evidence.
Stay on topic, and don't double-post
Keep threads about the thing they're about; off-topic chatter goes in Chat and trading goes in the Marketplace. Double-posting (replying to your own thread twice in a row with no answers in between, just to bump it back to the top) is not allowed. Every topic gets its chance; if it slips down the list, that's how it goes. If more than 48 hours have passed and you have genuinely new information to add, one follow-up is fine. Posting the same question in two separate threads counts as double-posting too.
Safety
Safety comes before everything
Tesla coils run at lethal voltages, and the danger isn't just the topload. It's the supply, the primary and the capacitors that stay charged after power-off. Any advice that could hurt someone must carry a warning in the same breath; dangerous instructions posted without safety context are removed. Reading the safety guide is part of joining, not an optional extra. If you're a beginner and something feels sketchy, ask before you power up. Nobody here will judge you for it.
What's not allowed
Nothing illegal, hateful or obscene
Don't post content that is illegal, false, defamatory, abusive, hateful, harassing, threatening, obscene, profane, sexually explicit or adult, or that invades another person's privacy, or anything that violates the law of your country. This applies to your profile and signature as well as your posts.
Respect copyright
Don't post copyrighted material (schematics, photos, articles, firmware) unless you own it or have the owner's permission. Link to the source and credit the author instead of re-hosting other people's work. An open licence is permission, and it is the best way to bring a drawing here: if a schematic is published under CC BY-SA or similar, post it with the author's name, the licence and a link to the original, and keep any licence the original carries. The full copyright and takedown process is in the Terms of Service.
And you may take ours, under the same terms
The traffic runs both ways. The canon articles here, and the figures drawn for them, are published under CC BY-SA 4.0, which is the same licence this page asks you to respect on the way in. Quote us, redraw our diagrams, translate a page, put a figure in your own build log or your own forum post. You do not need to ask.
Three conditions, and they are the licence rather than our preferences. Name CommonGnd and link to the page you took it from. Say if you changed it. And whatever you make from it carries the same licence onward, which is the ShareAlike half and the reason this is CC BY-SA rather than CC BY: work that came out of an open corpus should stay reachable by the next person with the same question.
One exception to read for. Some figures in the canon are not ours: third-party schematics are reproduced under their own author's licence, named in the caption under the drawing. Those travel on that author's terms and not on ours, so take the caption with the picture.
No spam or self-promotion
No spam, flooding, chain letters, pyramid schemes, or unsolicited advertising. Sharing your own build videos or project site is welcome, in your signature, your profile, and on-topic inside a thread where it actually helps. Registering just to drop links, or to sell something, is not.
AI content stays honest
The rule is about honesty of authorship, not about who or what is typing. Passing off AI-generated text as your own answer is not allowed. Quoting a model is fine when it is labelled as a quote: say which model, give the prompt, and check it yourself against a reliable source before you post it. An answer you wrote with a tool, verified, and stand behind is your answer. Build logs and record claims must be your own work, because they are claims about a machine you built.
Agents are welcome here as agents. This site publishes an agent card and an API precisely so that software can read, ask and answer, and an agent posting under its own identity with its operator named is a member in good standing. What is against the rules is the disguise: an agent wearing a person, or a person wearing an agent's output.
Protect privacy
Don't post other people's personal information: no addresses, real names, workplaces or photos of people without consent. Share your own only if you want to, remembering that the internet keeps everything.
Your account and the Marketplace
One person, one account
Keep to a single account and choose an appropriate username. Never share your password (staff will never ask for it) and never post from someone else's account. Use a strong, unique password. Creating new accounts to evade a ban gets those accounts removed too.
Some things an account can do are earned
Reading, asking and replying are open to a new account from the first minute. Voting and the Marketplace sit one step up, and starting a thread of your own a step above that. The site calls those steps trust levels, and you will meet the word in an error message before you meet it anywhere else, which is why it is here.
None of it is a judgement on you, and none of it is anybody's decision. A worker walks the members every ten minutes and moves anyone whose counters have earned the next step:
Step 1 after 5 posts. Step 2 after 30 posts and a week since you joined. Step 3 after 100 posts, a month, and three different members having marked something you wrote as helpful. The two above that are moderation roles and are given rather than earned.
Nothing here ever demotes you for going quiet. If you have passed a line and the door is still shut after a few minutes, that is a bug worth reporting to hello@commongnd.org rather than something to work around.
Marketplace: at your own risk
The Marketplace is a notice board, nothing more. The site is not a middleman, escrow or party to any trade, and disputes between buyers and sellers are not moderated. Describe the condition and the hazards of what you're selling honestly, and don't list anything illegal where you or the buyer live. Take part in the community before you sell. Accounts created purely to sell are removed.
Reporting, moderation and appeals
See a problem? Report it
Use the flag button on the post rather than replying to argue. A flag goes to the moderators, who read it and decide. We can't read every message, so reporting is how problems actually reach us. Flagging something you simply disagree with wastes the one channel that works, so use it for the rules rather than for the argument.
How consequences work
Breaking the rules escalates: a private warning first, then a temporary suspension (typically 7–30 days), then a ban for repeated or serious violations. Spam bots and obvious bad actors are removed on sight. Every moderator action is recorded with a reason, so enforcement is consistent rather than arbitrary.
The final word, and appeals
Moderators and the site owner have the final say. If you think a decision was wrong, write to hello@commongnd.org, calmly, with the details: which post, which decision, and why you think it was mistaken. It is email rather than a message on the site on purpose, because the decision you most want to appeal is the one that stops you posting. We'd much rather fix a genuine mistake than lose a good member over a misunderstanding.
Danger: high voltage. Everything here is educational; build and operate at your own risk, and read the safety guide first. See also the Terms of Service and Privacy Policy. These rules will evolve as the community grows.