Graham Gunderson's Energy conference presentation Most impressive and mysterious

[Spokane1]

Oh, I forgot to annotate the signal path. The BNC on the right looks like a signal input for the 74ac14 hex inverter. It looks like the signal is going through 2 gates on one side and 3 gates on the other side, so the two brown wires coming from the 74ac14 are carrying cleaned up and squared-off in-phase and out-of-phase versions of the input signal. Where they go? I dunno, maybe to the H-bridge gate drivers. The other BNC at the top.... I dunno.

Dear TK,

Good work on annotating that photo. It takes some time to put those labels in there and re-post it. It looks like our conclusions are pretty much the same. We don't know what he has going on there. Fortunately were are pretty sure what the purpose of these components are and we can move ahead with our own design for this sub-system.

You are correct on the unknown voltages. I used +12 and +5 as reference points. The actual voltages are probably higher since most all of the IC's are CMOS.

You are also correct on the presence of off-board connections. This close up photo was taken after the convention when Graham was doing further experiments. I suppose he had a variable pulse generator and a frequency meter hooked to the board. Rieyuki has a nice photo of the logic board configured for demonstration mode. I shall draft up both versions. (In progress)

Thank you for your technical contribution.

Spokane1

[Spokane1]

Dear TK,

Do you happen to have any idea as to what the function is of this sub-circuit is in the bottom half of the attached schematic? My first WAG is that it is some kind of fixed voltage reference network, if so that is a lot of components that could be replaced by a single voltage reference chip.

Thanks in advance.

Spokane1

[TinselKoala]

Dear TK,

Do you happen to have any idea as to what the function is of this sub-circuit is in the bottom half of the attached schematic? My first WAG is that it is some kind of fixed voltage reference network, if so that is a lot of components that could be replaced by a single voltage reference chip.

Thanks in advance.

Spokane1

The whole circuit doesn't make sense to me. Did you sketch that from the photo of the breadboard? I admire your perseverance and determination!

But I've certainly never seen a dual comparator used like that. Checking the pinout of the ts372 and the schematic,  I notice that the inverting input of C1 comparator is connected directly to the noninverting input of the C2 comparator and to nothing else (Pins 2 and 5). And the resistor-diode string leading to the Pin 3 noninverting input of C1 is completely bypassed by a length of wire (the WT-OR wire on the right side). Not only that but the diode in the string is reverse-biased, which makes no sense, so no wonder it's bypassed. So let's say that there is a small voltage coming from the bottom part of the circuit. This voltage is then present at the Pin 3 noninverting input of C1. Since there is nothing to compare it to (no voltage at Pin 2) the C1 output at Pin 1 goes high and stays there. Meanwhile some small fraction of the voltage from the bottom part of the circuit goes through the diode-resistor string on the left and is presented to the Pin 6 inverting input of C2. Again, there is nothing to compare this voltage to (no voltage at Pin 5 which is only connected to Pin 2). So the output of C2 goes low and stays there.

If the voltage labelled Vcc supplied to the bottom part of the circuit is a constant DC voltage, then that part of the circuit can only supply a fraction of half the Vcc voltage to the comparator inputs, and this will also be constant, I think.  Why all the components there.... I have no idea. You are right, if it's supposed to be some kind of regulated voltage reference it would be far easier and simpler to use a TL431 circuit there.

This is just a first pass, I could be completely wrong. I may try to breadboard the circuit later on to see what actually happens. I don't have a TS372 on hand so I'll have to try it with a different dual comparator or op-amp though. It is possible to configure comparators as oscillators but I don't think that's happening here, and that connection between pins 5 and 2 has got me very puzzled. Comparators are supposed to _compare voltages_ coming in to their inverting and non-inverting inputs. If one or the other input has no voltage supplied to it -- what's the point? Generally one input is used to read a set reference voltage and the other input is the "test" or varying voltage that you want to compare to the reference. In this case the "reference" voltage for both comparators is floating, undefined, since pins 2 and 5 are simply connected together and to nothing else. Or maybe the "reference" voltages are coming from the bottom circuit, in which case they are being compared to nothing--the floating pins 2 and 5. Maybe it would oscillate randomly under those conditions. Makes no sense to me.

The connection between 2 and 5 is a common way of setting up a "window comparator" circuit but it is always connected to a reference voltage, not just to each other.

[gotoluc]

I've been playing with this a little and it looks like I can get a similar wave form with just using 36vdc chopped by a mosfet switch around 21.7kHz with a 33% duty cycle to a primary coil which has a 0.002uf capacitor connected in parallel tuned to resonance (21.7kHz).

Yellow is a x100 Voltage probe across primary coil, Blue is a Tektronic P6021 current probe on negative of primary coil, Red is the product (math) of V x I and Purple is the DC output of the secondary (after FWBR to a 27,000uf cap with 20 Ohm load).

Luc

Hi Ben,
nice to see you here

the coil was around 10mH with a ferrite core. Use your signal generator (at 33% duty cycle) to turn on and off the mosfet's current to the coil which has a .002uf  to .005uf cap connected in parallel across it. Tune the frequency till you get (single Wave Ring) Resonance.

Kind regards

Luc

Sorry Ben and any others that have been trying to replicate the sine wave (posts above) with the information I provided.
Looks like the effect only happens with a bi-directional switch which I was using at the time and did not realize it was that configuration allowing it to happen.
Today, I was trying to make it work with a single mosfet and got nothing close. Then connected the bi directional switch and it works. So it looks like you need 2 mosfet's triggered at the same time with one flipped so the current can go in either direction through your switch.

Sorry I missed that.

Luc

[TinselKoala]

Is it possible that the .01 cap on Pin 6 actually connects over to Pin 5 instead of to Ground?

Still makes no sense though.