Claimed OU circuit of Rosemary Ainslie

[MileHigh]

battery charging
Without the diode, the voltage spike at the coil is easily 10 times the plus voltage. And with the diode, it was about 4 times the voltage.

Sounds exciting Aaron!!!!  Big spikes, we all want big spikes!  They must be charging the battery big time!!

Some nutcase is saying that the spikes are smacking the MOSFET!  Just like in the old days where dad smacked his kid in the head with a rolled-up newspaper to keep him in line.

So who is going to arrest the coil-resistor?  lol

Somebody needs circuit design counseling....

MH

[Hoppy]

@Hoppy: Could you please show both traces, like I did above? The voltage drop across the current viewing shunt, Ainslie's Point B, and the voltage at the positive rail side of the inductive load, Ainslie's Point A, on the same screen at the same time?
Thanks.
--TK

(The battery capacity could be a factor here. If your battery is low or not enough amp-hour capacity the voltage will drop radically when the mosfet turns on, but your trace shows a voltage drop to zero--that cannot be right.)

Another thing is that there don't seem to be any spikes or ringdown visible. Even the stray inductances in the wires, and the built-in inductance in the mosfet, should be generating visible spikes here.

You might try using a small 18-24 volt light bulb, which will be about 3 ohms and 100 microHenries, as a load to visualize what's happening. It behaves electrically much like an actual "Ainslie load" (except for the OU of course, we couldn't have OU flashlights after all) and can be quite revealing.

TK

I don't have a suitable lamp to hand but I did try a 250uH choke and this gives me a visible spike of 0.4V but even at this inductance, these spikes count for nothing in power terms.

I think Aaron needs to get himself an analogue scope before he goes any further with experimentation!

Hoppy

[poynt99]

A scope shot across the load resistor (aka the "inductor"-resistor).

Inductances in the circuit are from the load resistor (8.64uH) and parasitic inductances in the MOSFET leads. No other inductances are used in the circuit for this shot.

Note the nice ringdown in the zoomed shot. This is with the flyback diode installed.

.99

[TinselKoala]

OK, if I am interpreting the posts right, Hoppy says he is using the probe tip at the positive rail side of the load and the probe ground at the other side of the load. But that's not what .99 said. But you are agreeing...

Now, to be consistent, and to be able to compare results with Rosemary's cited results, we have to use the same measuring points. Look at the Quantum article and the EIT paper.

I have ALWAYS used the Ainslie points A and B, simultaneously, which of course requires that the channels use a common ground, that is, the negative rail.

The Fluke 199 is completely isolated though; it appears that even the scope channel grounds are isolated, so it might be possible to use different ground references with that scope, but that is unusual.

I agree that the channel "A" as Ainslie has it, from positive side of load to ground, provides little useful information. But that is the place where Ainslie shows it being monitored. And it is here that one will see the ringdown, the spikes, the diode effect.

Hoppy's monitoring, directly across the load, shows even less useful information, and of course if that's what's being shown, there isn't any difference with AC or DC coupling.

However, using Ainslie's point A, as I have been, you can clearly see the effect of coupling, and the spikes, and the load ringdown and all the rest.

I have no problem monitoring any point at all, but certainly we should know what's being monitored, and try to compare traces from the same points.

As I said, I ALWAYS refer to the points as named in the Ainslie paper; I ALWAYS use the same common ground for both channels unless otherwise specified; I ALWAYS display the traces in the "normal" polarity (the Philips cannot even do trace inversion); I always display the "B" current trace on top and the "A" load voltage trace on bottom.

And VERY IMPORTANT:
I  indicate where "zero" is (or the DC offset zero) on the scope display, by checking it with the probe shorted or the channel grounded, and then marking it with a little line on the white tape.

[poynt99]

Voltage across the shunt zoomed in on the same pulse.

The ~90% rise time looks about perfect (about 4.32us)

Second shot zoomed in to see ringing.

.99