Lenzless resonant transformer

[itsu]

11 kHz, now you have working replication :-) I was unable to see what was going on in the isolated LC in my setup, I could only see output light which maximized somewhere between 10 and 11 kHz.


Lets simplify the circuit so there can be only one resonant frequency. Connect those secondaries in parallel (as Mags already noticed) using just one capacitor (this was my first setup). You have CW-CCW coils so start of CW must be connected to end of CCW. C is reduced so resonance frequency will increase a bit. This is good in terms of L3, higher frequency means more blocking there.


The one time I used capacitor in L3 I tuned it like this:
1. I used L2s in parallel with just one 1000 nf capacitor in series with the load so no isolated LC here.
2. Connected load in the output and looked for the frequency that gave highest amount of light without a capacitor in L3.
3. Disconnected load so L2 side was open and placed a cap so that L3 resonated at the same frequency as the secondaries. I think cap was 73 nf (three 220 nf in series) and I got close enough.


When I tested this, I connected the L3 cap while the system was running and it gave bit more output light (10 watt and 8 watt halogens in the output). Enough to notice it. Did not notice anything in the input side as the 5 watt halogen there was not lit at all. Sweet spot did not change if I dropped the 10 watt halogen off which is good.


Secondaries should not affect primary so this tuning method worked. But there is also some capacitance between L3 and L2 that goes right under it, and also local inductance field is present from the secondaries so there can be some influence. This should be small enough to be ignored though.


With 11 kHz and higher tuning capacitor can possibly be dropped from L3 as it can block better, but I am not sure about this when using signal generator as source.

Ok i followed Jack's directions and paralleled the both secondaries with only one (double) cap (1100nF).
Without bulb it resonates at 10.5KHz (signal injected through L3)

After hooking up the bulb in the secondaries LC, its resonance frequency raised to 18KHz.

Then searching the L3 for resonance (injecting a signal through the both paralleled secondaries without cap/bulb) which was 1MHz.
Bringing down this frequency to 18KHz by using 70nF capacitance (where have i seen that value before).

Now both L3 and the paralleled secondaries with cap (1100nF) and bulb resonate at 18KHz.

In this situation,

Input voltage and current (from FG) are in phase
Minimum input current (is this what you mean by blocking the current?)
maximum input voltage
Maximum input power  (144mW) from FG
maximum output power (122mW bulb max. lit   see picture*)

* as i forgot to measure in the video the voltage/current (power) across/through the output bulb, the picture shows the
blue trace the voltage across the bulb and the green trace the current through the bulb with the red math function blue * green = avg power
(times 2 for the currentprobe terminator)

Video here:  https://www.youtube.com/watch?v=BE7tAbYRg7w&feature=youtu.be

Regards Itsu

[verpies]

Yes, i am glad to do any exp. frequency sweeps in XY mode. I think it will be very enlightening.

Well then, find/make a short BNC-BNC cable to connect the CH1: Mod/FSK/Trig connector with the CH2: Mod/FSK/Trig connector - both located on the back panel of the DG4102.
The remaining connections are shown below.

Principle of operation:
SG-CH2 generates an horizontal exponential time-base for the scope using a Burst mode and applies it to the X channel (Scope-CH1).  The looped Triggers on the back of the SG are for synchronizing the start of the exponential time-base (SG-CH2) with the start of the FM Sweep on SG-CH1.
SG-CH1 generates an exponentially FM modulated sine wave for exciting the DUT and the DUT's response is sensed by the Y channel (Scope-CH2) for vertical display of the amplitude response.

The capacitor and resistor, that connects the front SG-CH1.Sync output to the Z input (Scope-CH3), will have to be chosen experimentally (they determine the marker gap through the "Z gate" input ).   To estimate their values I'd need to know if CH3 of the Tek scope can be set to 50Ω impedance.

Programming of the SG and Scope later...

[Magluvin]

Ooops, sorry.  My last post with the pdf attached, I forgot to post the other pdf on the multi cores that I was talking about. I usually post them together as they complement each other.

Ive read it several times, and in it all, the one thing that is probably key to the whole article(below) is the fact that loading the secondary wont kill resonance of the primary.  But it doesnt illustrate the use of a bifi coil, or an LC, which could be run at resonance, it just states it.

Mags

[Magluvin]

No change in inductances of L1 or L2 whether or not L3 is shorted or open, it stays 710mH  (no capacitors in use).

Regards itsu

   L3 is well isolated from the affects for the secondaries.  So we can assume there is very little if any flux leakage to the outer sides of the core, unless at or around saturation.

What I cant get around with the orientation of L3 vs either L1 or L2, is the fact that L3 would want to initially magnetize the core through its diameter, but loading a secondary would want to magnetize the core through its loop shape. Im wondering about all the interactions of the primaries affects on the core mixed with the sec affect on the core. Does that mix have an advantage or disadvantage of in vs out.  Where with the separate cores, the cores will not have that mix of the primary trying to magnetize the core as if it were a bar or rod, and the sec trying to be in the circle, all at the same time.  And if the primary is trying to treat the toroid core as a bar/rod, then there should be flux leakage, N out one side of the diameter, and S out the other. But, possibly the 'mix' sucks, or say guides magnetically, the primary field all into the loop of the core.

Mags

[MileHigh]

Itsu:

In your latest clip where you have L1 and L2 in parallel and a single capacitor, you still have a very high resonant frequency, implying that L1 and L2 are in a "flux fight" and canceling each other out.  So if you cross one set of wires then L1 and L2 should add together and you should go back to a low resonant frequency.

Verpies:

A "true closed-loop toroidal core" has less reluctance than air, thus a winding over a closed permeable toroidal magnetic circuit will have higher inductance than the same winding over a less permeable magnetic circuit (e.g. one containing air gaps). 

In other words, a "true closed-loop toroidal core" offers less reluctance than air and causes more inductance, which means more reactance and less current, thus less of an "AC short-circuit"

What I was trying to compare was the "L3 straddling" configuration with having L3 wrapped around the toroid in the normal fashion, just like L1 and L2.  So then the coupling factor between the primary and the two secondaries (I think it is called 'k') would be much better (low reluctance path) and much more energy will flow through the magnetic circuit and hence you will get a "stronger AC short."  The larger inductance of L3 works "against" you and you get more of a nasty power burn in the windings.

Jack:

Presence of local inductance field can possibly be proved easily. If same amount of turns is used but there is more space between turns then resonant frequency will go up as the influence of wire to a neighboring wire is reduced while 'looped inductance' stays the same.

I don't know what you mean by "local inductance field."  More importantly, there is essentially no "influence of a wire to a neighboring wire."  That sounds like an old wives' tale.  In the context of winding wires around a toroid to make an inductor, it's the permeability of the core, and the number of turns that really count.  Also, the core can only store so much magnetic energy before it saturates.  There is a culture of experimenters neglecting or being afraid to correct each other on the forums.  That leads to stagnation, people don't learn because nobody corrects them and it becomes a vicious circle.

MileHigh