Claimed OU circuit of Rosemary Ainslie

[ramset]

User Ren offers help
Hi Aaron,

In regards to variable duty cycle/on time I have a schematic here that drives a TL494 PWM and allows for complete control of pulse width and frequency, as well as dead time, which may or may not be needed in this case. Anyway, it will directly trigger a mosfet from the output, or it can be sent through an opto coupler and the output transistor can drive the fet or transistor etc.

Will go up to 600kHz plus by simply changing the cap off pin 5. Lower the value for higher frequency.

Pulse width can be varied from 0 on time, to 100%, I think it would be perfect for this circuit.

If you are interested I can email it to you, I need to check with the author who gave it to me whether he is happy for it to be posted in the thread, I dont think he will mind at all, but best to be sure.

Anyway let me know if you are interested and whether you can source the TL494 locally, I will check with the author in the mean time.
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Ahhh the smell of burning mosphets
I know its not AM or RA circuit anymore
I wonder if Ren knows the peace love light show me the PATH to money ,I copy wright bowel movements deal
Chet
f

[jibbguy]

Get over the "triggering". It's just not happening for you. Put a triggered waveform on and turn the Trigger Level until it breaks lock: It will ROLL like a "Horizontal Hold" problem. NOT A SOLID ENVELOPE... In order to look "all white" like that, the F will have to rise considerably first (...so the time base is now set way too slow). Otherwise, it will just look like a quickly moving around representation of the original waveform.... Not a solid band.

As as for the MOSFET not having enough time to turn on, and that being the actual reason for raising the charging V and not the oscillations themselves... If that is true then when he gets it to oscillate at different F's and duty cycles, it should make a measurable difference in this charge voltage change amount then, as compared to before. Because this effect you suggest can only happen at certain "Lucky" combo's of F and duty cycle... Since we NOT talking about reaching the maximum rise times of the MOSFET itself (which should be several orders of magnitude faster than the operating F's we are concerned with here).

In your vid, i am not convinced at all that this is the same effect Aaron is seeing, or that Rosemary described.

For one thing, i do not think what we are concerned here with are actually "Parasitic" as you described, but another effect all together that has to do with forcing the MOSFET into an unstable state somehow (which has nothing to do with what we saw there).

Secondly, you said you are triggering on it "just fine" , but you were NOT triggering on it at all, you were still triggering off the "normal" waveform which had been magnified off the screen. You are trying to sell us oranges and we want apples

The usual "M.O." of these astable runaway oscillations, as i was familiar with since they happened a lot with op-amp and discrete transistor instrumentation differential amplifier circuits, is that they tend to obliterate the main waveform and can't be triggered on, as they are essentially a mass of mostly random transient spikes. That's why i was glad to see Aaron's waveform band because it closely matched what i have seen in the past. 

But not to worry folks, the study of this circuit will be done carefully and diligently, by many good peeps. What we may find, who knows yet: What we do know is, that pissing on it can't put out the fire hehehe

[ramset]

Comment from Jolt [I don't think he means any disrespect with the last sentence]

Ramset for a quick reply from me.
I did try to replicate it now, what i did at the Vid, and i couldnt,
maybe i still did not arrange it right now, because i did change all again.

Anyway, Arron did use a 10K Pot at the Gate?
He mentinoned, that maybe a 1k is enough, for the Gate Pot.
Seems for me anyhow, the 100Ohm Resistor at the Article is to low,
for wich Reason ever, maybe its was a different Element.


And my other Thinking, that the Shunt and the Resistor must match in a Way too.

Thats what i had at my Setup.
Plus ->Timer - 50kPot - Gate Transistor
Plus -> 600Ohm/10WPot - Coil - Drain - Source - 5kPot - Minus.

Where the 50K was very low set.
The 600Ohm should replace for me the Resistor at the Circuit, what is around the 24 V Batt.
The 5k Pot and the Coil was for the Shunt other Side.
Now i have actually 5 Pots, 2 at the Timer, 1 for the Gate, and 2 at the 24V Circuit.

Maybe he can get it into Oscillation when he use a higher Pot, otherwise, i can only think of, that he put some more Pots into the Circuit from the recover Part in Serie
and try to match the Parts to eachother.

But thats just in case, he has nothing else to do, as to play with it.
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[TinselKoala]

Come on, Jib, you are ignoring the evidence of your own eyeballs. At 6:40 -6:51 in Aaron's vid, where he is fooling with the timebase and voltage, the scope is clearly rolling, just as you say, and when it rolls nice and fast you see the bands.  And when it locks you can see the waveform clearly.  And in my vid at 3:54 you see the same stuff, rolling bands, but not at a fast time base.

Am I going to have to switch to the Tek and make the exact same bands?

Haven't we been here before? It's like Deja Vu all over again.

If what I do looks like his and quacks like his, why isn't it the same as his?

(Oh, and re the maximum rise time of the irfpg50 mosfet: this sucker is "slow". Especially if you don't give it enough gate charge. Read the data sheet and compare it to the 2sk1548, and look at my hot-swap mosfet comparisons in my videos.)
http://www.youtube.com/watch?v=F8TCOS7VYlw

[ramset]

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