Testing the TK Tar Baby

[Magluvin]

(ETA: In .99's detailed analysis his sim shows an osc frequency of around 1.125 MHz or so, as best as I can tell, which is much more in line with the Ainslie report. He modeled the inductances right down to the wires connecting the batteries. Why is my osc frequency so high? Do my batteries make the difference?)

Would the batteries act as a form of capacitance in the circuit, that might affect the freq of operation? But then how did Poynt get that detail worked out in sim.

Would the freq change if you changed the inductor value? Would it change if you had more or less transistors in parallel thus a change in capacitance?

Or, does the input voltage have an affect on the freq of the oscillations?

Are any of these things different in your circuit in comparison?

Mags

[TinselKoala]

See ETA2 above.

[Magluvin]

Tk

In this vid....

http://www.youtube.com/watch?v=HK9TNFuvM2k&list=UUZFlznLV3IyePfbc2TfDetA&index=15&feature=plcp

The one we were discussing in Roses thread, at 3:58 or so, you show that the circuit has oscillations "with the battery out".  That is why I asked you about it.
Is the circuit you are using now any different that it wont oscillate with the battery disconnected?

Mags

[TinselKoala]

You mean, any different besides the 2n7000 mosfets, the 3-volt battery supply and the FG drive at the same level, and the inductor? No, no different. 

That is, the oscillations are caused by the same things, but in the 2n7000 case there is enough leakage and AC coupling through the capacitances that the circuit is actually powered by the FG, probably.

The IRFPG50 eats 2n7000s for breakfast, nobody is disputing that. You can't blame the big fellow if he's a bit less sensitive to tickling.

[Magluvin]

Im not trying to beat ya down over this. Im just trying to understand it from your perspective. It was just my understanding from that vid of your version of Roses circuit that the circuit still oscillates with the loop of the main circuit broken by removing the battery. In doing so, that means that the inductor is out of the circuit, and so is the shunt, the load also.  So now, being that you say that adding more inductors changes the freq of the oscillations, can we say that we could have oscillations without the inductor, but adding it in just alters the freq?  or....

I suppose if you had the scope across where the the battery was could complete the loop in some fashion. But that would mean that the gen IS powering the oscillations, being that the battery is out of the loop. No? 

Either way, that was my understanding, But if this beefier setup dont, then we have to assume that there are differences in the circuits, even though we might consider them the same. So any alterations to the original circuit could alter the outcome also. Yes?

Mags