Community rules
CommonGnd is a science-based forum for high-voltage builders, from someone's very first spark to record-breaking arcs. Two things come first here: evidence over opinion, and safety. We help each other, we're kind to beginners, and we don't exaggerate.
New here? Read these once, then come and introduce yourself in Start Here and ask your first question in Beginners. The rules are short on purpose. They are here 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 and leave the person out of it. "your grounding scheme will cause racing sparks, here's why" is welcome. "You're an idiot" is not. Never mock a beginner for asking a basic question. 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 against the rules too.
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. It does not grade your English or your manners. It looks for specific things someone could answer: part numbers, measured values, what the scope showed, what you already tried and what happened. A post with none of that can be held or refused. A long post needs more of it than a short one, because long posts with nothing specific in them are usually spam here.
If yours comes back, no moderator has judged you or your question. Add what you measured and post it again. Nobody can answer "My coil makes short sparks". "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. Discussion runs on hard evidence, measurements and reproducible test results. Politics, marketing and personal belief don't count. 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 really think you have an exception, bring proof that is undeniable, reproducible and can be checked independently. Extraordinary claims need extraordinary evidence.
Stay on topic, and don't double-post
Keep threads on their subject. 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, and if it slips down the list, that's how it goes. If more than 48 hours have passed and you have 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 topload is not the only danger. So are 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. Read the safety guide when you join. It is not optional. If you're a beginner and something feels sketchy, ask before you power up. No one 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
It works the other way too. The canon articles here, and the figures drawn for them, are published under CC BY-SA 4.0, the same licence we ask you to respect when you post here. Quote us, redraw our diagrams, translate a page, put a figure in your own build log or forum post. You do not need to ask.
The licence sets three conditions. Name CommonGnd and link to the page you took it from. Say if you changed it. Whatever you make from it carries the same licence onward. That is the ShareAlike part, and it is why we chose CC BY-SA over CC BY: work that came out of an open corpus should stay open to the next person with the same question.
One exception. Some figures in the canon are not ours. Third-party schematics are reproduced under their author's own licence, named in the caption under the drawing. Those go by that author's terms, not ours, so take the caption along 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 inside a thread where it is on topic and helps. Registering just to drop links, or to sell something, is not.
Say when text comes from AI
This rule is about who wrote what. It does not matter 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. If you wrote an answer with a tool, checked it, and stand behind it, it 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. The site publishes an agent card and an API so that software can read, ask and answer. An agent posting under its own identity, with its operator named, is a member in good standing. What breaks the rules is disguise: an agent posing as a person, or a person posting an agent's output as their own.
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 and replying are open to a new account from the first minute, and while the forum is young, so is starting a thread of your own. Voting, the chat, private messages and posting in the Marketplace and Build Logs sit one step up. The site calls those steps trust levels. You will probably first see the term in an error message, so it is explained here.
None of it is a judgement on you, and no person decides it. Every ten minutes a background job checks every member and moves up anyone whose counters have reached the next step:
Step 1 after 10 posts and a week since you joined. Step 2 after 30 posts, a month, and one member having marked a reply of yours as helpful. Step 3 is a moderator rank (it can mute and ban members below it). Reaching 100 posts, two months and helpful marks from three different members puts you forward, and the owner decides after hearing from the moderators. The level above that is the owner's. An account at step 0 that writes 30 or more posts within a day also waits for a moderator before step 1. Your account page shows how far you are from the next step.
You are never moved down for going quiet. If you have passed a threshold and the feature is still locked after a few minutes, that is a bug. Please report it to hello@commongnd.org instead of working around it.
Marketplace: at your own risk
The Marketplace is only a notice board. The site is not a middleman, escrow or party to any trade, and we do not moderate disputes between buyers and sellers. 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 instead of replying to argue. A flag goes to the moderators, who read it and decide. We can't read every message, so reports are how we find problems. Please don't flag a post just because you disagree with it. Flags are for rule breaks.
How consequences work
Breaking the rules escalates: a private warning first, then a temporary suspension (typically 7 to 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, which keeps enforcement consistent.
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. Appeals go by email on purpose, because the decision you most want to appeal is the one that stops you posting. We'd much rather fix a real mistake than lose a good member over a misunderstanding.
Danger: high voltage. Everything here is for education. You build and operate at your own risk, so read the safety guide first. See also the Terms of Service and Privacy Policy. These rules will change as the community grows.