Coupling experiments - Transformer Impedance matching (3/3)

#151 In this video I try out some experiments related to transformers, impedance mathcing, coupling and resonance. First I look at how coupling factor can be measured using the short circuited output method, and what are the major limitations, then proceed to measure the coupling using a bode-plot method. Finally, I test various transformers, starting with wideband applications, and finishing with narrow-band resonant transformers.
Previous videos on the subject:
Resistive matching: • Electronics tutorial -...
Lossless matching part 1: • Lossless Impedance Mat...
Lossless matching part 2: • Lossless Impedance Mat...
Transformer matching part1: • Wideband coupling - Tr...
Transformer matching part2: • Resonant coupling - Tr...
Transformer matching part3: • Coupling experiments -...
Current probes: • About Current Probes a...
Documentation and links:
www.omicron-lab.com/fileadmin...
www.tdk-electronics.tdk.com/d...
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[@nh2921]

Best electronics channel ever..I am a hardware engineer, watching your videos is my daily dose of knowledge..keep them coming please.

[@ashishderhgawen]

Loved this series on transformer impedance matching. This is the BEST video I have found on this subject. I will have to try this out. Keep making videos!

[@AndreasSpiess]

Very interesting video. We often use a nanoVNA to measure impedances. It would be interesting to see you using such an instrument because it is a bit cheaper than your setup. BTW: I feature one of your Videos in my today’s video on my second (HAM radio) channel.

[@FesZElectronics]

Thanks for the shout out! I will be investing in a VNA in the future, I think I'll also get a nanoVNA since it sees quite widespread use!

[@MR-fs2pc]

What can I say? Another clear and comprehensive discussion on a useful topic. Perfect mix of theory and practice 👏. Interesting to see the wavegen and oscilloscope working so well together.

[@vincei4252]

Excellent stuff. Thank you.

[@olivierconet7995]

Really well explained and demonstrated.Thanks !

[@arabeagle7591]

Many thanks for your awesome shift from theory to practical aspect. 👍👍👍

[@FesZElectronics]

I'm happy you are enjoying it! I will try to split things up like this in the future on more complex topics.

[@Telectronics]

Very nice video thanks ! The bode diagramm is also my favorite tool when I want to see wideband response from a system. If I understood it right you can do stability analysis with your scope now. So you only have to wind a injection transformer and you should be good to go. Maybe you can make video about that topic would be interesting !

[@philopatepataphil6696]

Thanks you

[@paradiselost9946]

would maybe be interesting to do this with a ZVS as an induction heater? despite having wound OPTs and playing with tube amps, i admit... it only just clicked with an induction heater! i found they have serious drawbacks as they use the tank circuit as the work coil... any short or major change in value and things explode. they really are a good circuit if you like making components emit smoke? so ive been attempting to isolate the work coil through an impedance matching transformer... had some damn good refreshers on the theory! very little explanation on how they actually interact with the load. lots of people talking about the ZVS part, but noone seems to have a clue when it comes to maximising power transfer or anything like that beyond "wind coil put stuff in coil. heating with eddy current. yay" take the work to be 1R with 1 turn, a 5 turn coil reflects back at 25R, the tank circuit will be shunted by that resistance (or series, that bit still messes with me...) and the power supply will "see" the load of 25R, power being limited appropriately via ohms law. then you can simply use an appropriate transformer ratio to deliver a resistance that the supply will tolerate, whilst also applying a sufficient voltage across the work coil to produce the current required... yeah, i stuffed one up, went the wrong way... lets say my 250W supply did NOT appreciate suddenly seeing what may have been 0.22 ohms. ive figured it wants about 2.2R as the final impedance to work into. waiting on a new bridge rectifier... did i say they like releasing smoke? i didnt expect the rectifier to go though... meh. as i have no ammeter at the moment, and an unregulated supply, i know its working at full power when it sags to 24V. theres a bit more to it as the inductance itself is critical for the resonance, but whatever... the basic idea that it does have to be impedance matched for maximum performance as it is just a transformer is sadly lacking in most explanations... currently also winding meself a nice transformer with a few taps and some water cooling. effing. not as easy at it looks in my minds eye... the whole subject also explains why ZVS flybacks can be so freaking lethal... the reflected impedance to the supply is virtually zero once an arc is formed... made a tesla coil driven off one directly and wow, did it make some nasty arcs! mmm, mmm, RF burn. i do love the smell of singed flesh :)

[@culeadragos]

Wonderful explanation and demo! Are those resistors non-inductive?

[@HitAndMissLab]

How is this frequency sweep done? Is that something built in into your oscilloscope?

[@FesZElectronics]

Yes, this specific oscilloscope and signal generator combination can be interlinked and they can perform such sweeps.

[@alaricsnellpym]

Is the 2% coupling IF transformer just terrible and broken, or is there a use for such poorly coupled transformers?

[@FesZElectronics]

The 2% was occurring without resonance; with resonance, you get far better results (with my setup Iwas getting 10-20% but better can be achieved); you do want small coupling to have a better overall filtering effect - so to only pass the usefull signal at resonance, and almost nothing at any other frequencies.

[@biswajit681]

Please bring topic like 3 phase inverter ,BLDC motor

[@MrCircuitMatt]

This was very nice, thank you! Can you explain the purpose of the 50 Ohm series resistor? To me, it looks like this is not required since the source already has 50 Ohm internal resistance and you terminated the load with 50 Ohms...

[@FesZElectronics]

Indeed, the signal source does have the built in resistor, but by adding this extra resistor, I can better reproduce the simulation results - in the simulator the reference signal is coming out of an ideal voltage source, and the 50r is after that. With the oscilloscope I can only measure what is coming out of the signal source (after the internal 50R) so by adding this extra external resistor, from the point of view where I am measuring (the signal gen output) there is only the 50R external resistor visible; whatever comes out of the generator is the reference.

[@MrCircuitMatt]

@@FesZElectronics I see. Thank you for your response and keep up the nice work!

[@researchandbuild1751]

I need a tutorial on how to do that bode plot on the oscilloscope! I have a Siglent 1202-XE, can I do a bode plot on that?

[@FesZElectronics]

It should be possible, as long as you have an appropriate signal generator from Siglent and a USB interconnecting cable. Maybe this link will help: siglentna.com/application-note/bode-plot-filter-oscilloscope-generator/

[@researchandbuild1751]

@@FesZElectronics Thank you! It looks like my particular model doesn't support bode plotting, at least not in a direct way, according to the information you linked. Thanks for helping me find that! I really love your videos you do things that I subjects I was always interesting in understanding better when I was growing up, and never got to see people actually DO them. I built some transfomers when I was younger in electronics school, but I didn't have all the modern tools (I'm 48 this year) to be able to see all the parameters correctly. I really appreciate how you explain why the graph looks a certain way especially when you showed the weird waveform with the secondary winding shorted in a transformer and that was happening because the frequency was not high enough yet for the secondary to have any effect. It probably would have taken a long long time for me to realize that.

[@jaygarner2911]

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