Mini Tesla coil kit = router reboot (actual reboot, not just internet dropping!) - Page 1
Forum section: electronics / beginners

author: jewelie
author_rank: Regular Contributor
timestamp: January 23, 2023, 11:45:01 pm
content: Playing with mini Tesla coil kit* = fun! ⚡🤪Router rebooting (actually rebooting, not just internet disconnecting) every time I use it, plus a smart bulb forgetting it's setting = less fun. 😒It's only running at 12V @ 600mA. I'd expect interference but causing that much of a problem seems a little curious? The router and smart light are on the same ring main, probably wired almost together (although actually physically in a different room), to the linear benchtop PSU powering it?Any thoughts? Is this to be expected or does it suggest a potential wiring issue? Anything I can do to reduce the interference (without spoiling the fun?)

author: james_s
author_rank: Super Contributor
timestamp: January 24, 2023, 12:02:32 am
content: You're sending enough energy through the air to light a neon bulb, I'm not all that surprised that it's causing equipment to malfunction. How far away is the router?

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 24, 2023, 01:10:39 am
content: Tesla coils produce wide band interference.Back when in the 1970s, a medium sized coil of about 60 cm, would cause distortion on a CRT TV’s scanning.Not only the image, but actual deflection

author: jonpaul
author_rank: Super Contributor
timestamp: January 24, 2023, 11:56:30 am
content: High voltage high frequency is very dangerous for any electronics.Both radiated and conducted EMI will be powerful enough to kill devis, cause RF bursn and disturb medical like pacemakers.Can happen even for the tiny Chinese junk coils shown.We run TC far from any devices and on separate mains feed.The real thig is here:https://themaverickobserver.com/tesla-eccentric-and-electric-teslas-tower-of-power-in-colorado-springs/Old friend Greg LEYH: Modern largest TChttps://www.lod.org/ZAP!Enjoy!Jon

author: magic
author_rank: Super Contributor
timestamp: January 24, 2023, 12:01:35 pm
content: If you want to know if it's through the air or through mains, try to find some battery to run it from.

author: jewelie
author_rank: Regular Contributor
timestamp: January 25, 2023, 01:35:20 am
content: Sorry for the delayed response everyone. Thanks for your help!Quote from: magic on January 24, 2023, 12:01:35 pmThat's exactly what I tried afterwards. On batteries there's no problem (although I've yet to formally check it's running at exactly the same power.)Quote from: james_s on January 24, 2023, 12:02:32 amTo be fair it only lights it if I'm adequately grounding it, but yeah.Router: Very near. Less than 4 feet, certainly (it's on the other side of a wall, hence the ambiguity.) Same with the smart bulb (although that seems to lose it's settings at the drop of a hat, to be fair.)I'm not surprised either. What bugs me is that by battery it was fine, suggesting mains acting as a conduit. Also, mobile, other equipment, not noticeably affected.Quote from: bigfoot22 on January 24, 2023, 01:52:13 pmI expected some RFI using it, hence just a few goes with it, although I didn't expect it to be as powerful as this.Our internet is VDSL2 (copper to local telecoms outdoor cabinet) so I totally imagined it impacting that. It doesn't, it just tends to cause the router (which is also the VDSL2 modem) to reboot.Risk of damage would presumably be related to distance, inverse square law stuff, would it really present a damage risk beyond just very nearby items?Talking of emergency bracelets etc... with the fibre internet rollout here in the UK, the powers that be have only recently cottoned on to that the dact that the fibre setups that carry the telecoms here being installed are mains powered with no backup means all these emergency systems won't work during power cuts, unlike POTS did. FFS.I didn't consider about the modem's supply being flaky! I might have a look at that and inside power circuitry. I think it's probably a linear mode one too by virtue of it's age. It's an old 24/7 device that will have seen lots of transients over the years.Quote from: jonpaul on January 24, 2023, 11:56:30 amHeh, the only (other) Jon I know also used to be a TC junky! (Jon in UK is normally spelt John.) Thanks for your input too, Jon.I'm normally strictly a 12V 0.5A max kinda gal who reads every manual first; if I *have* to e.g. probe mains, it's with a Fluke, connected by screw terminals, at a distance, turning mains on remotely, flinching as I do it......you'll not be surprised to know, then, that the coil kit was a present from a friend with the devil in him. This little coil has peaked my curiosity now! I honestly didn't expect it to work, or I at least expected it burn the coil out in seconds or something.Now I'm desperate to know what's going on with the RFI causing such an issue via the mains but not battery and, for that matter, what rough base frequency this runs at, and what voltage the coil is peaking at, and so on. Aaargh. And I can't do any of that without turning it back on, which I can't really do willy nilly because it's clearly more of a nuisance than I was expecting! I'm thinking about having one more quick go with a mains filter device I have on the PSU (capacitors plus common mode choke and MOVs IIRC), to see if it does prevent the noise that resets the router, and will pop the oscilloscope on as I imagine it'll pick up the noise through the air and then I might be able to see what frequency it is.Thanks for your input everyone. So, it seems this tiny thing does have the capacity to reek havok after all, and problems in the vicinity are to be expected. Oops!

author: bill_c
author_rank: Regular Contributor
timestamp: January 25, 2023, 02:12:56 am
content: The mechanical spark igniter on my stove restarts my network switch about 4 feet away. Doesn't seem to bother my computers at 9ft away.

author: jewelie
author_rank: Regular Contributor
timestamp: January 25, 2023, 02:43:31 am
content: Hmmm.So this circuit is a Slayer Exciter. No spark gap etc. Untuned.Would adding extra capacitance to this via a top-load reduce the RFI? It would be interesting to experiment more, and at home kits are the limit of it for me (mostly homebound and nowhere else to do it) but I really don't want to be a nuisance either.We've enough strange RFI issues around here as it is: my favourite was faulty communal TV aerial system plus local Police transmitter just below TV UHF which caused mains noise via earth that drove a trackpad mad when a laptop was plugged in (original earthed laptop PSU.) We've always at least a few broken florescents in the vacinity if nothing else, which plays merry hell with all sorts of things.

author: themadhippy
author_rank: Super Contributor
timestamp: January 25, 2023, 02:47:51 am
content: for your next project may i suggest plasma tweeters,good for wiping out yours and your neighbours tv

author: jewelie
author_rank: Regular Contributor
timestamp: January 25, 2023, 02:57:05 am
content: Quote from: bill_c on January 25, 2023, 02:12:56 amInteresting.Spark igniters are common everywhere and also produce wide band RFI, but they don't generally have much power behind them though?The slayer exciter circuit I'm using appears to consume about 6W, which I guess is a lot if it were being dumped as RFI, although I also suspect most of that goes into heating the transistor. Now I'm wanting to know how much power is being emitted as radio frequency.

author: jewelie
author_rank: Regular Contributor
timestamp: January 25, 2023, 03:07:30 am
content: Quote from: themadhippy on January 25, 2023, 02:47:51 amWell, yes, that'd be one way to make myself popular.Seriously though, I'm really *not* wanting to be a major RFI nuisance. If I didn't care, I would have just continued to play and experiment like many others do, rather than stopping using it and coming on to the forum to ask questions about it.

author: jewelie
author_rank: Regular Contributor
timestamp: January 25, 2023, 05:18:47 am
content: Had a quick go at 5am.My oscilloscope is VERY old, the timebase isn't well calibrated and it's only 10MHz.Putting a probe end within 6 inches or so of it:1. Signal from it is about 8MHz (and pretty stable.)2. Signal amplitude is within about an order of magnitude of the background mains hum (ignoring attenuation due to being near limit of the scope.)Mains filter doesn't prevent router reboots

author: jonpaul
author_rank: Super Contributor
timestamp: January 25, 2023, 11:48:41 am
content: Rebonjour cher jewelie, BRAVO for your questions and curiosity.Have worked in HV, ignitors, pulse magnetics dsince 1970s.In genral any ignition coil, tesla coil or indiection couil stores energy in a magnetic core or capacitor and a switch (vibrator, semiconductor, etc) is used to suddenely make and break the circuit.The resulting HV pulse on the transforme ror coils sec has very fast rise, ring waves and significant energy, radiated and conducted everywhere.Thus it si very difficult to protect sensitive electronics.We used EMI filters (common mode, diff mode) transient absorbing Zeners, MOV surge protection, gas gaps in various combinations.Normal consumer PCVs, mobiles, routers are NOT protected against such interference and may be permanently damaged.This entire topic is very deep and many books, seminars and papers exist for the professionals.I would keep the mini TC far ways from the router and any electronics, rn on a batter if possible and at nigh to see the best effects.Bon ChanceJon