Love the idea "Ghetto" electronics ! could be a series in itself !!...cheers.

Hi Richard. I was intrigued by your ring tester. Here’s a thought. Why not use your MESR to introduce a 100k Hz signal to the primary winding . When the last pulse is generated start a clock then time the voltage to reach half of VCC . The bad primary would have a very short time to that of a good winding. You could have a resistor divider on the inverting input of a comparator to set any fraction of VCC you choose. Also incorporate a switchable capacitor in the voltage divider to enable you to test different transformer cores (iron and ferrite). The output displayed could be the time mS or uS or the number of peaks (rings) above the setting. The upshot of this is knowing the frequency enables you to count the rings and also allows an insight to the Q factor of the inductor.

Interesting. Here's some food for thought, for what it's worth....Ring testers seem to operate on the assumption that a single shorted turn will very much impact the transformer's Q factor (ratio of inductive to resistive values) by adding a big resistive short circuit, thereby making a more damped response when you apply a pulse. And there's also an assumption the big short circuit will make the remaining winding unable to deliver its rated voltage. While some of that may be true in some cases and for some configurations, keep in mind that we're talking a single turn of wire, which is a very poor inductor. So the voltage induced in that single turn may be very small, and depending on the resistance of the turn the resulting current in that turn may also be very small. Which means the overall impact to the transformer's operation may be negligible. As an example I just tested a 120VAC to 12VAC mains transformer, wrapped a single turn of 22AWG wire and the open circuit voltage generated in the single turn was only 0.2 volts. And when I shorted it the resulting current was only 1.4 amps, compared to the transformer's 4A rated winding. The impact on the 12VAC secondary winding was non-existent. That being said, some real world transformer testers used by industrial and power companies use a form of ring tester (although it's a much more complicated impulse response test, as well as frequency scans, etc.) to check for short circuits, but they generally compare results to either manufacturer data or "known good" data. Personally, I'd take any simple ring test result ("good/bad") with a huge grain of salt. One other consideration is that if the short was caused by a voltage spike (as is often the case), the shorted turn may only be evident when high voltage is applied, since failed insulation doesn't necessarily mean a molten copper solid short circuit. Which is why professional testers generally use high voltage tests for this sort of thing.

I discovered counter EMF at the age of 6 with a single D cell powering an electro magnet, showed it to my Dad right away, both of us amazed. Enjoy your vids, still learning at age 70.

I used to love doing that with a relay when I was a kid. I sometimes added a capacitor in series or parallel with the coil, (I forget which and may have it completely wrong), to change the speed of the buzzing from what you had to about a car turn signal speed. There are at least two other practical applications I've used. 1. It is probably the sort of thing that drives ham radio guys nuts, but the thing is a very broadband RF emitter, basically a spark gap transmitter I guess. If you run a wire from the shocky bit to a metal connection to a water pipe the RF will go into the pipe or water in it. You can then use an old pocket AM radio trace the pipe underground for a few hundred feet. When I tried it, it was with sandy soil and the PVC pipe about 2 feet down and full of calcium rich water. Saved a lot of digging. 2. If you end up in an electronics college elective class and are asked to build a circuit to blink a light or make RF or apparently test a transformer, it is usually pretty easy to find a relay and capacitor on short notice, and there is a chance the professor will like the weirdness of it. 3. With a few alterations and minor additions it also can be used to make a practical joke electric chair to show appreciation for a favorite teacher. Not sure it is kosher to go into details, but don't cross the line kids and try it on your own butt first. If you need more than a 9V battery, you're doing it wrong and maybe doing something stupidly dangerous. The desired effect is an uncomfortable tingle not smoke and screaming and EMS and life in prison.

I liked that pcb ring tester and that is something I need to build and have in my tool box. This stuff is so interesting and sure the theory of operation of each component is important you can till test and find problems without an electrical engineer degree and that is all i need. Im a beginning hobbiest little projects are very good practice.

Suggestion: The switching frequency for that type of transformer is in the range of 50-100 kHz or more, that's why when you used the relay setup ( which switches at low freq ) you measured quite low voltages on the secoundaries. I suggest you make a 555 oscillator to generate high frequency oscillations and retry your expirement. I'm quite certain that you'll measure much higher voltages on the secondaries. Please put a mosfet on the output of your 555 so you can provide high enough current for the test. You can also make the frequency variable using a potentiometer so you can test multiple types of transformers.

How smart was that? The simplest answer to the most common and seldom resolved question for any guy who has ever encountered windings outside of an electronics workshop. Awesome ! This little genius experiment got me thinking in a way I never did about the magnetic interactions of the different windings and shorted turns. I have now reached the awareness from a physics vantage point that a shorted turn, wherever it is in a transformer, primary, secondary or made up ad hock with a looped piece of wire, is a stand alone, near to zero resistance, closed secondary circuit in itself. Its own current is not interacting at all with primary or any other secondary winding current from an electric point of view while it does from an electromagnetic point of view and has to be analyzed as such. Yeah I know, it's obvious but what can I say? I never thought of it like that before. I might be slow. Then all becomes clear if you know your physics. We know three things: magnetic variation creates EMF in a conductor, current through a piece of wire creates an electromagnetic field and variation of current in a turn creates an electromagnetic field that creates in the turn a counter electromotive force that tends to oppose the variation of current (inductance). The higher Tesla variation rate , the more EMF; the lower resistance, the more Amps; the higher Amps variation rate, the more contrarian Teslas. Current in a regular turn of a winding is limited by the reactance of the circuit while current in a shorted turn is not. Therefore, submitted to the same magnetic variation rate, the current through a shorted turn is completely electrically independent and significantly higher than the current in any other turns in any other winding, be it primary or secondary. Being approximately a linear function of the currents ratio in our case (almost synchronous current signals, different amplitudes), the current variation rates ratio between shorted turn and primary winding is also high. When the electromagnetic field produced by the primary varies, the induced current high variation rate (because of the high current pics) in the shorted turn creates a significant contrarian electromagnetic field that dampers the overall magnetic variation rate hence lowering the EMF in the secondary. One shorted turn contraries the EMF like dozens of regular turns, perhaps a hundred all because of the high current variation rate ratio between the shorted turn and the primary. For the addicts, maths here are not too heavy and it starts with the self generated electromagnetic field in the center of a turn being an increasing linear function of the current in the turn. Also the current in the shorted turn is an increasing linear function of the current in the primary whose factor is the resistances ratio. Differential equations for the current variation rates and the electromagnetic field variation rates reduced to a spiral approximation are quite basic. Finally, lower electromagnetic variation rate overall produces lower output voltage in any secondary winding, basically like when the output current draw increases, increasing the contrarian electromagnetic field in the secondary which requires a higher current variation rate in the primary in order to sustain the overall electromagnetic field variation rate and so the output voltage. The resistance you added to the primary played a major role for that matter in lowering the current in the primary therefore increasing the current variation rate ratio with the shorted turn hence increasing the output voltage drop reading. Obviously with this particular circuit, the most significant voltage drop will happen with the first shorted turn and the series is logarithmic. When a second shorted turn occurs, the electromagnetic variation rate has been seriously degraded already by the first one so the induced current variation rate in the second shorted turn is noticeably lower while the current variation rate in the primary hasn't changed, so the current variation rates ratio is lower than for the first shorted turn, so the added contrarian electromagnetic effect is noticeably lower, so is the voltage drop reading as it will be so, with decreasing effect, for any new shorted turn. Rich, how about you add a potentiometer in series with your shorted turn and build a manual output voltage regulator out of it ? Man, this one was a kick in the butt. Talking about a wake up call and I have to thank you for that.

When I see a KZfaqr using a Fluke multimeter I think "that guy probably knows his stuff". My Fluke 75 is 30 years old and still going strong.

Nice option for a comparative test

Very good and simple idea, thanks for U, Vanakkam , Nandri 🙏

Using the relay like continuous oscillating would soon burn out the contacts? I remember way back in 60’s I used to work on lots of relays and contact burn/wear was very common! Another problem was oxidising contacts where very low currents were switched I.e. audio signals being switched like in dictation equipment! Gold plated contacts were supposed to cure that problem but no or noisy signals ( frying eggs )were a nightmare! Phone exchanges were a nightmare (crackling frying etc ) when you wanted a dial tone! Solid state switching cured all that stuff! Fraser

In spite of the fact that the transformer under test would likely be designed for a primary voltage of about 350, it is probably being driven to saturation with the test circuit. Without knowing the configuration that would have been used in the original circuit I'd guess it was a forward converter and likely limited to 50% duty cycle. At 100 kHz, that would equate to 350 V x 5 µs = 1750 V•µs. At 12 volts you would reach that at 146 µs ON time. There isn't the slightest shred of a chance that the relay circuit would be applying anything remotely close to that short. The transformer would have been driven into very hard saturation. Most of the energy would simply be generating heat, in the case of the test circuit in the resistor, and nothing of interest with regard to detectable signal. This sort of crude circuit would probably be OK with an iron core power transformer. With the SMPS transformer, I'd experiment with using the primary as the inductor in a boost converter. You could use the relay as the switch. I'd try a 1N4148, which is extremely fast, and a small 100 V cap, possibly with a 50 V zener across it to limit the voltage. I'd try about one or two volts to start with for the input to the boost circuit. Using the winding in a boost circuit and ignoring the secondaries removes uncertainties of the phasing in the windings.

That poor door bell…… I mean relay 😉. As ever, very interesting and I learned something new from these past two videos. Thank you.

I have a circuit diagram of t he ring tester in kit form that I built years ago and it is the best for this kind of fault finding and it really works well it shows the condition of the windings with leds that light up! IT is quite simple and effective for line output transformers and other SMPS Transformers used in older technology television systems and such it is very effective and helpful 🤓

We call this the chattering relay test in the EMI testing world. We wrapped one turn around the unit under test and we watch for degradation or upset.

Try snubber diode , cap and resistor across relay coil to protect contacts! Fraser

Another good video,thanks

I would have liked to see the real size of those back EMF pulses on a scope. The trouble is you could damage the front end of the equipment trying to measure the pulses. I don't think your Fluke liked those pulses much, plus I'm not sure what frequency or bandwidth the Fluke responds to either. You mentioned how you would get shocks off similar circuits in the past so I believe you could have been generating spikes well above 50volts to be able to feel them ! A single pulse might give a better result with a storage scope capable of handling the back EMF voltages adequately. We normally mount diodes across coils to suppress this back EMF spike so it doesn't damage the semiconductor driving the coil, so I would expect the peak back EMF to be much greater than 50 volts. Rich, please don't blow up your scopes proving or disproving this !!

Heya I have worked at a transformer bild company SMIT transformers the biggest I helpt bild was 900 KVA that is pretty big. I know they had there own lab to simuleet lighting hits before they were sent to there working place but I never heart of a ring tester maybe for those kinds of trafo's it's to big lol

I did the same basically, as a kid, I made a model of a electric fence, in a board, powered by a lantern battery, 6v, and a bell motor, it was on a board, with a copper wire fence, and aluminum foil for the ground, touch the 'ground' and the fence , you get a tingle, It was the 5th grade. I built a generator, using a electric motor, and a generator from a old Chevy truck, as science projects,. The friggin volcano won! 😧

1:06 Ingenious idea because... we all got a little ghetto in us. LOL! 😎

Behalte die GUTE ARBEIT ..DU IST DER BESTE...

great vid as always. are you planning a video about oscillator circuits?

Seemed the 2nd shorted turn wire was smaller gauge than the 1st (maybe folded al-foil could work better?). I do see another useful video here: Spruce-up digits on the trusty Fluke 79 by cleaning the LCD's zebra strips with IPA👍

You need to use a scope to see the noise pluse .

8:50 The DMM shows 1,95V when the relay is not actived, and the voltage is jumping all over the place. The voltage on the DMM should be more stable when you use a bench power supply as power source,so there is definitely something wrong in this test setup.

As we are talking about small resistances, induction and all sorts of gubbings is it valid with all those croc clip cables lying around Lol ! whatever, it's interesting just messing around....cheers!

Hi ☺️ i think you can test shorts with an oscilloscope and amp curves, like ignition coils , what you think 🤔

Got me thinking, what if you connected a speaker to the output instead of the diode, the cap and the multimeter? Would it be easier to compare the effect of adding another shorted turn? It might require a an amplifier though. Also, warn people not to connect it to the microphone input or line-in of a computer or another sensitive device. It would be even more noisy but that's the ghetto way lol.

Would it be possible to measure and compare the AC current passing through the shorted turn instead of the output voltage change? It would simplify it.

how about building a isolation transformer and dimbulb tester in one device that is a nice build project and you can teach how it makes repairs safer by having that kind of device / kit I would sure watch that video because there is the calculation of how much Va the transformer has to be the danger of grounding and the benefits of the current limiting with the bulbs and how you can combine both in one housing ... maybe a fancy one with volt and amp meter inside electronic fuse switch for ground or no ground etc as doing repairs you should do it safely think that would be a very good video topic for your channel maybe build it in a live stream so viewers can ask questions during the build and where to get the components that are used ..... what you think ? would it be something you like to do ?

PS for those that do not have a MESR meter use a 555 timer to generate a 100k Hz signal.

Even cheaper and fewer components - normally open push button, relay (SPDT) and power resistor - connected to power supply and oscilloscope. Regards, David

Handy stuff 👍🇮🇪💚🙏🏼

I can see the electronics nerd teenager rattling relays while the other boys were smoking behind the shed and ogling young girls 😅

The damping of the ringing will change.

This looks like it might be frequency sensitive and adjustable for better results..........

I couldn't see exactly how you connected the "second turn" BUT in order for it to BE a second turn it SHOULD have been connected in series with the first, otherwise you just had two single turns in parallel which is just ONE shorted turn! Moreover, typically, shorted turns (plural) are the issue, rather than just one or two and the same applies to motor field coils, armature coils etc. These have two points separated by several coils that end up shorting together especially under applied high voltage (breakover). So what you ACTUALLY have is a coil, connected to several shorted coils in series, then to the rest of the coil internally. This is very different to applying a single external coil that you then short. The internal multiple shorted coils a) present a MUCH lower impedance and inductance and b) are in the primary or secondary magnetic path generation not externally parallel. To do this kind of test properly, the single or dual (series connected) external turns should ALSO be connected in SERIES with the primary or secondary depending on which you wish to test. NOTE: WHEN TESTING THE PRIMARY CIRCUIT DO NOT EVER APPLY MAINS WITHOUT A SERIES CONNECTED LOAD SUCH AS A LIGHT BULB. NOW if the external turns are shorted they will be shorted within the coil of the winding under test and WILL have a much greater impact. Remember that the external coils have "direction" and should be wound the same way as the internal coils ... Just test with different ends of them being the "start" of the coil and connect in series with the coil under test. This method will ensure that the full (or greater) normal current is passing through the coil which with a separate external coil or coils it won't! Remember it's amp turns that generate volts and that voltage is what drives the current so the difference between current through a single isolated and shorted coil is MUCH less than that through a SERIES connected one! Remember to apply some external load when testing the secondary or no current will flow through the external coil/s so short or no short will show little difference.

Ring tester is the best

Nice to see a coated wire short the output. Seeing is believing. Lol

ok so a shorted transformer will couple less volts to the secondary, but if you dont know what the normal volts are, you have no idea if theres an internal short or not! I cant see how this circuit proves anything

Cool...

The noise is upsetting your meter.

I still think a ring tester is easier and that poor relay 😂😂😂😂

whats you doing,😄

Why don't "simply" make some maths to calculate the power absorbed by the trafo in case one suspect any problem with it ? 🤔

ƤＲＯ𝓂Ｏ𝕤ᗰ 😂

Ridiculous.