did i break physics? - Page 1
Forum section: electronics / projects

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 03:21:36 am
content: i have a 17 volt transformer i soldered a bunch of thinks together, the dip sockets being outputs as this was supposed to be for a vfd tester i was building but when i went to test it with my multimeter i found 50v where there should have only been 25, anyone got any ideas? did i break physics?

author: zlymex
author_rank: Frequent Contributor
timestamp: September 22, 2016, 03:28:25 am
content: Multimeter problems?High frequency interference?Analog multimeter on AC range?

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 03:36:33 am
content: what high frequency? i checked it 10 times against know value and 10 out of 10 my multimeter was accurate and i dont have an analog multimeter

author: Rerouter
author_rank: Super Contributor
timestamp: September 22, 2016, 03:39:25 am
content: I havent looked at the PDF, but i experienced something similar before, a 18V transformer, measured 18V AC, but when i rectified it, measured 42V DC, had to pull out the scope to figure it out, turns out the transformer was somewhat resonant with the RFI filter caps i had used, and was spiking up to 45 volt but only for a very short period.

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 03:40:53 am
content: ill test it on my oscilloscope but my multimeter wasnt flying all over the place it was rather solid value but i don't know if that means much

author: helius
author_rank: Super Contributor
timestamp: September 22, 2016, 03:44:35 am
content: Some of you may enjoy this lecture on the topic of "breaking physics":See if you can spot what he does "wrong".

author: timgiles
author_rank: Regular Contributor
timestamp: September 22, 2016, 04:44:24 am
content: As with all those on Youtube that claim similar, if you consider that all the scientists at CERN, spending billions of Euros, manage to 'break physics' only a few times over 15-20 years of planned operation, I doubt if you have managed it with a single capacitor!

author: ZeTeX
author_rank: Frequent Contributor
timestamp: September 22, 2016, 05:05:01 am
content: Then your transformer might supply more then 17V with no load.this is an easy test, wire up your transformer to the mains, connect it and then measure AC voltage using your multimeter.if a transformer is sold as 12V it might supply 13V or 17V no load, because they spec 12V on it at load.

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 05:29:43 am
content: Quote from: ZeTeX on September 22, 2016, 05:05:01 amits used and it was thoroughly tested to be 17 volts and you never know stranger things HAVE happened it might be 1 in a trillion for all i know but i do doubt it or i wouldnt be asking here, here is my theory i think somehow it is in series with itself or perhaps as suggesting resonating

author: Rick Law
author_rank: Super Contributor
timestamp: September 22, 2016, 05:36:45 am
content: Quote from: neo on September 22, 2016, 03:21:36 amDamn! It was you! I was wondering why gravity is not working for me, and I thought it was what I was smoking.

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 05:43:10 am
content: Quote from: Rick Law on September 22, 2016, 05:36:45 amthis is without a doubt the funniest joke iv'e heard all year.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 22, 2016, 07:54:13 am
content: Transformers are usually specified at full load. For a cheap, small transformer, the off-load voltage can easily approach 2x the full-load voltage, especially when you also consider variation in mains voltage.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: September 22, 2016, 08:12:09 am
content: Quote from: neo on September 22, 2016, 05:29:43 amMaybe somehow the transformer spikes to an higher voltage and the capacitor just holds the peak, ofcourse with even a small load this will drop.what is the W\VA of your transformer?

author: Fungus
author_rank: Super Contributor
timestamp: September 22, 2016, 08:16:03 am
content: Quote from: neo on September 22, 2016, 03:21:36 amDepends on what you mean by "transformer".If it's one of those old copper-wire&iron things then there's no mystery, you've just rediscovered 'inductance'. Put a load on the output and it will drop down.

author: Ian.M
author_rank: Super Contributor
timestamp: September 22, 2016, 11:18:38 am
content: First I'd want to check the multimeter - a fresh 9V alkaline should read between about 9V and 9.3V on its DC volts ranges, and on its AC V ranges, assuming its CAT II or better, the mains supply(measured via a lead fused at no more than 3A - for your safety, firmly connected to your test probes so you don't have to touch or hold any part of the wiring with the power on), should read within 10% of 120V. If itsNOTCAT II or better rated don't attempt to check your mains supply voltage.TLDR: Before claiming physics is broken, sanity check your instrumentation!

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 02:00:26 pm
content: maybe it is inductance, as for the mention of sanity checking my equipment i crosschecked it 10 times

author: Ian.M
author_rank: Super Contributor
timestamp: September 22, 2016, 05:34:24 pm
content: Photo please, so we can see the s--t you are actually testing and see how you have it hooked up. What's the measured AC voltage across the ends of the secondary and what's the make and model of your meter?

author: max_torque
author_rank: Super Contributor
timestamp: September 22, 2016, 05:56:40 pm
content: Have you soldered TWO output windings in series by an chance??Ie dual tap output, both of 25V, in series you get 50V!

author: neo
author_rank: Super Contributor
timestamp: September 22, 2016, 07:13:39 pm
content: no because this is the only one though that was my first thought

author: ZeTeX
author_rank: Frequent Contributor
timestamp: September 22, 2016, 07:22:12 pm
content: Quote from: neo on September 22, 2016, 07:13:39 pmOK, upload a picture of your setup, show us your transformer, show us how you measure the transformer output voltage, show us how you measure the 50V.Don't replay unless you have pictures - this is going nowhere.

author: Fungus
author_rank: Super Contributor
timestamp: September 22, 2016, 11:15:09 pm
content: Quote from: neo on September 22, 2016, 02:00:26 pmIf there's no load on the transformer then it's inductance. No need to look further.Put a load on the output (eg. a 220 Ohm resistor) and watch it drop down.

author: Macbeth
author_rank: Super Contributor
timestamp: September 22, 2016, 11:27:06 pm
content: This whole thread reminds me ofBatteriserBatteroo doing all their battery voltage tests with no load whatsoeverThe mysterious +/-17V is from what? Without anything to go on here why even bother?

author: Audioguru
author_rank: Super Contributor
timestamp: September 23, 2016, 02:43:25 am
content: The schematic does not show a transformer and does not show a rectifier. Instead it shows inputs of +17V and -17V feeding one 1000uF capacitor and the +17V input connects to the +50V output and the -17V input connects to the -50V output.

author: Ian.M
author_rank: Super Contributor
timestamp: September 23, 2016, 03:00:00 am
content: You think that's bad, you should see his schematics in hisother topic!They're about as useful as a London Tube map on the Moscow Metro.

author: Audioguru
author_rank: Super Contributor
timestamp: September 23, 2016, 03:00:21 am
content: The schematic does not show a transformer and does not show a rectifier. Instead it shows +17V and -17V inputs connected to a polarized 1000uF capacitor and the -17V input connects to the +50V output and the -17V input connects to the -50V output.

author: neo
author_rank: Super Contributor
timestamp: September 23, 2016, 05:02:14 am
content: Quote from: Ian.M on September 23, 2016, 03:00:00 ami will conceed my schematics are terrible but this one doesnt allow me to draw a transformer easily and the other is just really complex

author: StillTrying
author_rank: Super Contributor
timestamp: September 23, 2016, 01:04:25 pm
content: The best fix would be to delete this whole thread.

author: Buriedcode
author_rank: Super Contributor
timestamp: September 23, 2016, 04:26:24 pm
content: From what I can gather (you haven't made it easy..) you have a mains transformer, the secondary is tapped to give 17V-0V-17V, and you've slapped a 1000uF cap across the two 17V nodes. So you have 34V RMS across the cap. We have no idea how you measured this, what multimeter setting or anything else involved. But if we find the peak... 34 / 0.707 = ~48V peak. Pretty close to 50V. How did you test this transformer?Even if it was rectified, you still have 34V RMS, which when rectified can easy get to 48V I assumed you rounded up.I didn't see a rectifier, so that poor cap gets 34V, then -34V across it - did it complain via the standard procedure of exploding and making nasty smells?

author: neo
author_rank: Super Contributor
timestamp: September 23, 2016, 05:15:41 pm
content: Quote from: DiligentMinds.com on September 23, 2016, 04:45:16 pmonly one primary 3 secondaries, 17v 2.2v and 1v full wave rectifier yes, and those readings are with nothing else no label 120 mains

author: Monkeh
author_rank: Super Contributor
timestamp: September 23, 2016, 06:00:43 pm
content: What the f-That is not how you connect a bridge rectifier.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 23, 2016, 06:07:10 pm
content: Quote from: Monkeh on September 23, 2016, 06:00:43 pmBridge rectifier? Where?

author: Monkeh
author_rank: Super Contributor
timestamp: September 23, 2016, 06:07:34 pm
content: Quote from: PA0PBZ on September 23, 2016, 06:07:10 pmPoint.

author: neo
author_rank: Super Contributor
timestamp: September 23, 2016, 06:08:31 pm
content: sorry

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 23, 2016, 06:08:52 pm
content: Quote from: DiligentMinds.com on September 23, 2016, 06:05:39 pmWell, it looks like GND is connected to the transformer however you render it...

author: neo
author_rank: Super Contributor
timestamp: September 23, 2016, 06:11:37 pm
content: sorry it isnt

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 23, 2016, 06:11:51 pm
content: @neoTry this:

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 23, 2016, 06:13:30 pm
content: Quote from: neo on September 23, 2016, 06:11:37 pmThen don't put the label GND there, or is that another PDF failure?

author: neo
author_rank: Super Contributor
timestamp: September 23, 2016, 06:32:45 pm
content: i dont know where my oscilloscope leads are

author: Ian.M
author_rank: Super Contributor
timestamp: September 23, 2016, 07:05:45 pm
content: Not everyone has access to a scope. While its careless to mislay the leads (even if some tealeaf has nicked them while your back was turned), we can probably proceed on the basis of meter readings if you have a few simple components to make test jigs e.g any of 1N4002 up to 1N4007 diode, a 100uF 100V capacitor and a 10K 1/2W resistor. It would also help if you provide a photo of the hookup of the transformer, rectifier and big capacitor, and also provide the make and model number of your meter so we can check the specs of its AC ranges.

author: R005T3r
author_rank: Frequent Contributor
timestamp: September 23, 2016, 07:06:56 pm
content: The transformer you are measuring at the secondary is in a particular modality called "no load", because ideally, a multimeter is a open circuit. Actually that working principle, is very important, because if no load is attached you will have only losses at the primary windings and core losses.All transformers(and all other motors as well) are made like that in order to compensate the voltage losses when you are working on the "nominal plate" point. every characteristics (especially transformer constants) above or under the nominal point is going to change.Actually you have this result in any transformer (including the 20KV ones!), but it is way more noticeable on a step down transformer because you work with higher amounts of current than mains ones...

author: Audioguru
author_rank: Super Contributor
timestamp: September 23, 2016, 08:29:57 pm
content: I corrected the schematic but I suspect the transformer is 17V-0-17V which is 34V center-tapped to produce a rectified and filtered 44VDC. Then with no load it might measure 50VDC.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: September 23, 2016, 10:35:05 pm
content: neo,There is a button called "quote", in the right side of the comment.if you want to reply to someone, click on it and then write your comment, this way we know to which person u are talking to.can you please take a picture with your phone and upload it here? in the picture we want to see the transformer, the multi-meter that shows 50V and your wiring.

author: pepelevamp
author_rank: Regular Contributor
timestamp: September 24, 2016, 02:15:05 pm
content: hi guys my alarm went off. did someone break physics?

author: neo
author_rank: Super Contributor
timestamp: October 02, 2016, 05:04:03 am
content: it was inductance i think anyways i found my oscilloscope probes but before i could thoroughly test it let out a gigantic spark and went down to 24 volts permanently

author: StillTrying
author_rank: Super Contributor
timestamp: October 04, 2016, 08:31:36 pm
content: Quote from: neo on October 02, 2016, 05:04:03 amProbably just yet another PDF, (Potential Difference Flash), - nothing to worry about.

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 06, 2016, 04:34:51 am
content: Quote from: StillTrying on October 04, 2016, 08:31:36 pmLike this?EDIT: Your secondary had half of it shorted thus doubling the voltage. The fault burned away so it works now. However the insulation is probably screwed so it may short again or burn out entirely.

author: neo
author_rank: Super Contributor
timestamp: October 06, 2016, 05:29:12 am
content: kynar insulation doesnt burn as far as i know, not easily at any rate