Hard to justify electronics design urges? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: April 27, 2025, 08:03:46 pm
content: Have you ever had any hard to justify urges or interests in electronics ?I really wanted to wind a inductor with resistance wire, to make a RLC filter that is missing the R damper. It turns out its kind of possible but the resistance might be a little lower then you want (for textbook critical damping), if you buy thin resistance enamel wire (invar) and select the right core. I figure alot of people thought about doing this but no one ever did it, not for a low frequency signal inductor anyway. I thought it was very satisfying to actually connect that part into a LCR meter.. and then I stopped working on itI spent alot of time and some money on that, even though I did not really have a useful application, something just drew me to it. I did stumble upon telegraph wire after doing that though, which is interesting... the idea is the whole wire is a inductor 'bead' (wound in magnetic metal tape, like mu-metal) so it satisfies transmission line requirements for long wires. Not really too related but I doubt I would have learned about that otherwise, because its just not something I would read about normally.Another strong urge is using trees as antennas, but I managed to contain that urge. It however has been on my radar for a long time...And another one that has been occasionally nagging me is to upgrade a old composite carbon resistor test equipment (like some HP box, preferably having to do with higher frequencies) to replace all the carbon comps with ceramic composition resistors.Expensive. Basically anything will practically work in the circuit instead (I like to use metal oxide personally). But I think ceramic composition would be the 'true' replacement. (and its only available 10% in some sizes). I know that the presence of coils that were not normally there must irritate some people that restore things to no end.... its like incorrect. There are not supposed to be coils there, it was supposed to be a near zero inductance lump of resistor material, not a spiral. It also bothers me to have MLC capacitor to replace a SLC capacitor....

author: electron_plumber
author_rank: Regular Contributor
timestamp: April 27, 2025, 11:33:09 pm
content: QuoteMost people put the damping element in series with capacitance, not the inductance, so that it only damps the AC-component and not the DC component.Then again, I'm thinking power... maybe you're thinking signal filtering... although, that's basically what a ferrite bead is!QuoteBelieve it or not, there are some publications on VLF tree antennae!https://apps.dtic.mil/sti/tr/pdf/AD0742230.pdfSpeaking of trees, I've always wanted to put a tesla coil inside a small Christmas tree. This way, you can decorate the tree with LED ornaments that are energized wirelessly. No more annoying strands of lights!

author: coppercone2
author_rank: Super Contributor
timestamp: April 28, 2025, 12:57:51 am
content: There is a handbook for using trees for HF or something, its some where in the RF forumYes, its for signals. This would be for the low frequency region where people are obsessed with active filters now (they don't like even teaching about low frequency RLC signal stuff anymore). I know why, because I bought a entire big series of inductors of various kinds for my lab and it was very expensive, people don't like spending $3-5 a part... but I started to think its silly that I have instruments that cost very expensive but people are squeamish about owning a say e-24 series of inductors in through hole!A dampened capacitor is much harder to build. Something like building a capacitor out of carbon fiber comes to mind for your power version. Or maybe graphite.Lol, now I want to rebuild a butterfly capacitor with graphite sheets or carbon fiber panels or something. It's a start.Same research from inductors, the most lossy metal is tungsten, then you have the semiconductors and carbon. Carbonizing a film capacitor seems similar to metalizing, but the problem is probably that it can't sink heat, since those damper filters probably have parts in the 10W rating range for the damper resistor? It would have to be built like a ceramic capacitor I think. A heat sinked carbon or semicondutor? filled MLCC, maybe with a little heat sink. Or a carbonized PTFE cap (rolled), might be able to do some dissipation too.I just wonder if you can get the ballpark resistance you need (ignoring heat for now) in a foil capacitor structure.....You could possibly make a PTFE sheet capacitor rolled under oil at home (the oil while nasty would prevent arching from air gaps if you are careful maybe, the main problem with home made caps and HV), or even like a oil paper cap with... carbon paper instead of aluminum? But if you did real edge bonding (low inductance) on the foil, the resistance might still be pretty low. Teflon and silicone oil DIY capacitor might be able to run pretty hot.But wow I wonder if that could work and even be pretty durable.it must be made. I have a feeling that developing that will take a few years out of your life and set you back quite a bit. At least the high ESR coil is comparatively very cheap.It's like something out of a david lynch movieHaha, imagine clueless people had to pick the right one too. Like for some industrial repair. With the J term written as the value.Starts to look like a motor oil specification. Don't worry about that part, it never gets that cold here. But how many miles per hour is this circuit going??

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: April 28, 2025, 10:04:53 am
content: Are you taking the resonant approach to filtering by any chance?QuoteGraphite butterfly cap! Now that sounds like something truly exotic.I have a very large butterfly cap from my grandfather but its badly rusted, although interestingly its still extremely smooth to rotate. Maybe it can be fixedQuoteAll the time. Its usually stuff that no one truly needs (including me, to an extent) but I get obsessed with it for a while. An urge that speaks "this thing should exist, just for the sake of existing"A few months ago I really wanted to build a "battery transient response profiler". A device which could accurately put transient loads on the battery and record its response so that a corresponding RC model, or maybe a piecewise linear function can be created to be used in simulations. Then I realised, no one actually needs this. In the real world its much, much easier to use a larger battery or add additional decoupling instead of living on the edge of battery's capabilities.I have tons of projects that I start with great enthusiasm and the excitement just fizzles out. I'm sure its the case with most hobbyists

author: electron_plumber
author_rank: Regular Contributor
timestamp: April 28, 2025, 01:23:48 pm
content: Quote from: BadeBhaiya on April 28, 2025, 10:04:53 amI've designed vehicle power electronics at a few companies and we always measure and model battery impedance. It's useful to have something in your simulation when you solve for your harness damping elements. Also helps predict conducted emissions, etc. A transient response tool would be neat; but I've always just used a bode plotter and an injector, that way you can measure impedance while loaded.