Testing the TK Tar Baby

[TinselKoala]

Can anyone tell me why one battery was removed from the 60 volt stack, leaving 48 volts,  for the second part of the NERD RATs video demonstration?

If I recall correctly RA and .99 decided that a 36 volt battery with lower amp-hour capacity would be fine for testing the NERD device. Well... it's pretty clearly not fine for Tar Baby, since we see no evidence of battery recharging.

Of course we haven't yet looked "under the rug" of digital scope dumps to spreadsheets for analysis of improperly obtained data for that evidence. We can only go by the actual state of charge as determined by draw-down tests of one kind or another.

[TinselKoala]

I've disconnected the battery from the circuit, and scoped across the power _input_ leads to the Tar Baby.

So this is the same probe location for battery monitoring, except with the battery completely gone and the scope set to 2 volts/division instead of 20 or 50 or even 100 v/div as the NERDs have shown.

And then I turn on the FG. Guess what.... the FG's voltage appears at the power input leads, which means -- I think -- that the battery will be seeing the FG as a power supply.

For strictly negative going gate pulses, the FG voltage appearing at the power input leads has a funny shape and not much amplitude. But when the gate pulse goes positive at all, whether from bipolar pulsing and/or a positive offset for the negative pulsing.... this full voltage of the FG's output appears at the power input leads.

[TinselKoala]

I repeated the Function Generator Battery Charging experiment, except I used one of the 12 Volt, 5 A-H batteries of the Tar Baby. I hooked up the negative lead from the FG to the negative battery terminal. I hooked the positive lead from the FG to the _anode_ of a 1n4009 rectifier diode. I hooked the _cathode_ end of the diode to the positive input of the inline DMM ammeter, and I completed the circuit by hooking the negative side of the DMM ammeter to the positive terminal of the battery.

I turned on the FG and set it for a positive pulse only, 13 volts amplitude, then increased the duty cycle to about 70 percent, which gave me +120 mA indicated on the meter. The FG is charging the battery !! When I started, the battery was at 11.4 volts. Now, after a few minutes, it is at 11.6 volts and slowly very slowly climbing.

[MileHigh]

TK:

I think that you built the NERD circuit using the topology in the uploaded diagram below.  You can see if the function generator output goes positive that you get a good conduction path through the internal diodes of the Q2 array so your scope voltage reading makes sense.

If the function generator output goes negative then you have quasi turned on the Q2 array but the drain is open-circuit except for the internal impedance of your scope probe of about 1 Mohm.  So that means that the low source voltage from the function generator on the Q2 source pin is "imaged" on the drain pin.  But to see any "action" in theory you have to have a good conduction path on the drain side, which you don't.  (more below)

If you ever try it again you should try the same setup but also see what your scope reads if you also put a 100k, 10k, or 1K resistor in parallel with the scope probe.  You can assume that when the function generator output is high or low that you will see the fg voltage across the resistor load.

For the fg output going high, it's due to the diode in the Q2 array.

For the fg output going low, the fg now actually powers the Q2 MOSFET switch.  Just "move the fg counter-clockwise around the loop" in your mind and you can see that the ground of the fg is at the high potential, pumping current through the added resistor, through the switched-on Q2 array and the back to the signal lead of the fg, which is at the lower potential. Call it the "new ground."

Going back to normal 36-volt operation, the fg cannot recharge the batteries.  If the fg output is high, it obviously doesn't have the EMF required to power the battery stack.  If the fg output is low, it acts like one more battery in series with the battery stack.  That can't recharge the battery stack, it can only contribute to the power output of the battery stack.

Magluvin:

Sorry but I could not make head or tail of 95% of your posting about the motors and stuff, and it would be better on another thread.

MileHigh

[MileHigh]

You can certainly see how the circuit that TK built is functionally equivalent to the NERD RAT circuit.  The first small build that TK did with the 3-volt battery pack was kind of a "proof of concept" circuit to show how easily MOSFETs will oscillate.  At least that's how I see it.

It's been stated before and it's worth stating again that MOSFET circuits are highly prone to oscillation.  A circuit designed to be an amplifier and a circuit designed to be an oscillator are very similar.  So when you use MOSFETs in some kind of switching application that has inherent amplification, it's not in the least bit surprising that the circuit will start to oscillate.

What frequency the circuit oscillates at is mostly academic.  The core of the design will oscillate.  Sometimes all that it takes is a bit of thermal noise, which is everywhere in circuits, to tickle the MOSFET input and start the oscillation.  Different lengths of wire or other inductive or capacitive effects will influence and change the oscillation frequency, but that does not change the fact that at the core of the circuit there is an engine running, powered by the power source, that is doing the oscillation.

So what we are looking at has not fundamentally changed from day one.  It's a circuit that takes power from a set of batteries and burns off that power in an inductive resistor, a MOSFET oscillator, and other sundry components.  The fact that the MOSFET oscillator runs in the 1-4 MHz range with harmonics that extend up into the tens of MHz means that the whole circuit is "buzzing" with a superimposed high-frequency AC voltage signal that makes measurements very difficult to do.

You can't forget the nonsensical aspects of the circuit either, with the function generator in the main current loop when it's outputting a negatively offset signal.  That means that the function generator is both contributing to the powering of the circuit in tandem with the battery array, and at the same some time dissipating some of the power running trough the circuit via its internal 50-ohm resistor.  Also, the actual square wave signal being output by the function generator, under normal negative offset oscillation mode, has absolutely nothing whatsoever to do with controlling the ON/OFF switching of the current going through the inductive resistor.  The function generator is just acting like an "enable oscillation - disable oscillation" device.  It's somewhat bizarre.

The bottom line is that there is nothing here at all.  It's all just a giant misunderstanding by Rosemary where she is clinging to her DSO data capture and refuses to wake up and look at the data coming at her from all other directions stating that the setup is under unity.  If you had somebody that was really skilled they would be able to use the same DSO on the same circuit to capture good data which would show that the circuit was under unity.  Recognizing that the battery voltage has to be filtered to get rid of the superimposed AC voltage waveform would be an example of taking the proper steps to make proper measurements.

Rosemary is clearly not a skilled enough person to use the DSO properly nor does she understand how electronic circuits work beyond the most basic level.  The same thing applies to her NERD RATs.  How the circuit actually works was discovered _after_ she and her team worked on it for months and months and then presented their paper.

If you know how to use a screwdriver and a spanner you can't then just present yourself to a Formula One race team and proclaim that you want to be the lead mechanic with the pit crew.  That's a valid analogy for Rosemary and it's just as ridiculous.  She can pick up a scope probe and push a button on a DSO.  So what, that means nothing.   This notion that you are not "encumbered" when you are clueless with respect to electronics and science is simply ridiculous.  Blind ignorance does not give you the ability to have "new insights" that others with education and training are blinded to.  In the vast vast majority of the cases, all that you end up doing is deluding yourself.  That is clearly the case here.

MileHigh