Graham Gunderson's Energy conference presentation Most impressive and mysterious

[Spokane1]

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.

Dear TK

That was certainly quick work, Graham said that only 25% of the components on that board were actually being used. There is a good chance that that IC was not being used during the demo or at the shop (since the connections haven't changed).

IF you are interested in digging deeper into this logic circuit send me an email to mmckay@simplexgrinnell.com and I shall send you the raw photos I took at Graham's shop. They are too big to post at full resolution.

I'm just about finished with the overall wiring schematic for the board. Next is to do the Logic layout so we can establish how the various timing signals were derived.

Thanks again for your time and expertise.

Spokane1

[Spokane1]

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.

Dear luc,

No Problem with the oversight, is happens all the time, even at VW.

Would the requirement of a bi-directional switch in your circuit imply that the H-Bridge configuration will be a requirement in the Gunderson Circuit?

Spokane1

Luc

[TinselKoala]

OK.... er.... hmmm.  I breadboarded the circuit, sort of, and got some pretty strange results. It's a weird sort of window-oscillator, kind of unstable, but I finally got some consistent results out of it.

First, I had to use a TL082 op-amp as the comparator. This is another high-input-impedance dual opamp with the same pinout as the one Gunderson used. I didn't have any 0.01 uF caps to spare so I used 0.1 uF caps instead. This may affect only the frequency of oscillation or it may have other effects different from the original. When I can scrounge some 0.01 uf caps I'll re-test.  And for the bottom part of the circuit I simply subbed a variable voltage source (a pot across the supply rails with the wiper to the bottom of the 1k resistor in the center of the schematic.) I supplied the circuit with a little over 5 VDC.

The scopeshots below show the results as I varied the voltage input from the pot. The Yellow trace is the output of Comparator 1 (Pin 1), the Blue trace is the output of C2 (Pin 7), and the Purple trace is the applied voltage from the pot to the bottom of the 1k resistor.

[k4zep]

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

Hi Luc,

This is the best I can get with a single ended, actually just driving a circuit off a pulse generator.  The waveform is not symetrical due to that fact but it does work.  I think your
assessment is correct!!!

Ben

[TinselKoala]

Er.... nice work, but see what happens when you post a huge horizontal picture?

Please shrink it to 800 pixels wide and reupload it to replace the overly wide one, or simply use the scope's screen capture utility (stick a USB stick in the hole, press the green "print" button under the Help button.)
Not only will the screenshot look a lot better but it will be _much_ smaller in total file size, and it won't screw up the forum page from being so wide.