Rosemary Ainslie circuit demonstration on Saturday March 12th 2011

[TheCell]

It is interesting that a simulation shows the effect of charging the battery with even one mosfet used. Now you could exchange the mosfet with a normal bipolar transistor or / and exchange the lead acid battery e.g. with a lithium ion battery and watch if the effect still persists.
If the effect diminishes after exchanging the battery than it's a bedini thing,
if it does so after exchanging the mosfet , it maybe a case of negative resistor effect shown with it.

[Rosemary Ainslie]

hi Rosemary

if 4 out of the 5 MOSFETs are merely providing (rather unconventional) feed back to Q1 gate, how many are actually needed to achieve the same effective results (eg. as March 12)?  does it still work with, say: 4? ..3? ..2? ..1?

also, does any other particular number of 'feedback' MOSFETs appear to give a better result than 4 of them?

thanks
np


http://docsfreelunch.blogspot.com

Hi nul-points.  I'm afraid I can't answer this.  Once those clips are disconnected I can't reconnect them because I can't quite follow their threads.  It's my bad eyesight.  So.  I need someone else to do this test and the guys who work with me on this are just too busy.  I was, in fact, hoping to get some of this done today - but we got caught up with an entirely unrelated circuit.  They're trying to generate a continual oscillation without the switch.  Some really interesting results.  But too unstable at this point.  Apparently we'll have another go at this in a week or so.  When we've got it that it's more repeatable then I'll post that circuit.  Some interesting thinking. 

I'll also do some detailed tests on how many MOSFETs required during this coming week.  But I'll have to wait to find out who's available. 

Kindest as ever,
Rosemary

edited

[nul-points]

I think we all can agree on the established fact that a net MEAN negative CSR voltage would seem to indicate a net current going back into the source battery.

A question to Rose, and any of the readers here (it would be interesting to hear any thoughts on this):

Is this apparent reversed current going back toward the source battery a consequence and product of the circuit operation itself, or is battery chemistry involved and somehow required to produce this reverse-current effect?

.99

i think that is a key question in starting to get a handle on the nature of any anomaly which may be present

tests have been suggested (some months back) to discriminate between these possibilities but the onus is rather on Rosemary to try some of these variations whilst keeping the remainder of the circuit unchanged, so we can be more confident that any different behaviour only follows the change and not anything to do with the build-specifics of other reps

(EDIT - however, i wouldn't expect battery-related effects to be evident in sim results)


my initial response to a CSR in the Vgs loop would be to move it to the drain side - but - it's just possible that the feedback from a Vgs shunt could be contributing to anomalous operating conditions

so on reflection i'd probably put this change on the 'try-one-change-at-a-time' list of follow-up tests

just my 2c
np


http://docsfreelunch.blogspot.com

[poynt99]

I was, in fact, hoping to get some of this done today - but we got caught up with an entirely unrelated circuit.  They're trying to generate a continual oscillation without the switch.  Some really interesting results.  But too unstable at this point.

Could you explain a bit more what you mean Rose? Are you saying you guys are attempting to make an oscillator with no active device at all, i.e. no MOSFET or transistors?

.99

[Rosemary Ainslie]

Rose,

I remember there was some suspicion that the Instek function generator may not be working properly (possibly damaged), but I thought it was subsequently determined to be OK. Is this now not the case? Is that why you now require another generator?

What model is the Tek generator you've now got?

.99

We had a first early ISO-TECH.  GFG H216A.  This gave us 3 minutes on the duty cycle - max 20% on or off - and it worked perfectly.  Then we tested this against a second identical model to check that the effect was not associated with vagaries related to that make.  The second - also an Iso-Tech - also fresh out the box - didn't work as there was something wrong with the duty cycle - that it would not adjust at all.  Then we tried a 3rd that worked as well as the 1st.  Because we'd marked the various optimised button settings on the first - we continued working with that.  We then got another 'new out the box' for the home demos - which is when we found we could only get 2.08 minutes from the switch.  Then we replaced this - yet again - and I 'think' we're back to 3 minutes.  But the waveform still has that 'hammer head' 'start' of each oscillation.  I now think this must have been the result of one of the MOSFETS that we needed to replace.  But I can live with this variation.  It's just a shame that we can't get back the early shape that did not default during the oscillation phase. 

We have still not tested the Tektronix.  Hopefully I'll start on this soon.  It's a Tektronix CFG280.  Not new out the box - but fully tested and fully calibrated.

Regards,
Rosemary