Rosemary Ainslie circuit demonstration on Saturday March 12th 2011

[poynt99]

The FG is connected in such a way to turn Q1 and Q2 ON and OFF in anti-phase, provided that the FG levels are set appropriately.

I think what we need is a firm confirmation of the circuit both for the actual "as-built" apparatus, AND what folks are using for a simulation schematic.

.99

[Rosemary Ainslie]

The FG is connected in such a way to turn Q1 and Q2 ON and OFF in anti-phase, provided that the FG levels are set appropriately.

I think what we need is a firm confirmation of the circuit both for the actual "as-built" apparatus, AND what folks are using for a simulation schematic.

.99

Poynty.  What you're asking for is a 'standard' representation of a non standard configuration.  To begin with the standard configuration of the MOSFET is to show the GATE between the source and drain when in fact the GATE is on the extremity.  It is also NOT standard to show the body diode of the FET.  These need to be factored in.  In other words the standard representation of the MOSFET is NOT consistent with each and every MOSFET on the market. 

If I had my 'druthers' then I would simply put the input from the FG directly onto the gate of Q1 and the ground at Q2.  Then I'd link the FETS as we do - Q1 gate to Q2 source - Q1 drain to Q2 drain - Q1 source to Q2 gate.  Then you'll see the point better.  Because what we've done is turned the MOSFET on its ear - that it can NOW read a negative signal as a positive. 

What I will do, later today - is see what happens when I simply put the ground of the FG directly onto Q2.

But PLEASE DO NOT assume that there's a standard way to show this.  There quite simply isn't.  There's nothing standard in applying a FET as we're doing it here.  And those that ARE doing the sims are aware of these problems.  They're trying different ways of showing this.  And the problem is NOT in the lack of a standardised schematic - but that there is NO WAY this can be shown in a STANDARD configuration.  It is decidedly NOT standard.

Added.  And if it works by putting the ground 'directly' on Q2 - then I INSIST that ANY schematic of this circuit - show precisely that.  I'll let you know what happens.

Regards,
Rosemary
   

[poynt99]

Rose,

MOSFETs have 3 pins as you know. From left to right; 1, 2, 3.

If the pin names (gate, source, drain) are a stumbling block for you and those working on the sims, perhaps you can draw up the new as-built apparatus by designating only the pin numbers and where they are connected.

I truly can not wrap my head around the problem you are having as you are describing. What the pin names are, and how the MOSFET is represented symbolically, is immaterial. All you need do is tell us how the MOSFETs are physically connected in the circuit, and if you wish to use pin numbers (i.e. 1, 2, 3) then please do. Use a box with 3 labeled pins on it if that works for you.

You really are stumbling on something that is an unnecessary self-imposed block to conveying this important information.

.99

[Rosemary Ainslie]

Poynty - a friend of mine who is really good at these things - has just evaluated the circuit and confirms that what you have drawn is 100 % correct.  What he does is put the FG input and ground - gate to gate.  But they are linked - obviously through the source.  He's the one who's trying to get a square wave signal generator with a negative swing - but not quite there yet.

So.  Your design is good.  Now you'll need to get it to oscillate.  You may need to add 3.3  micro Henries for inductance on the wires.  Maybe help?  Otherwise - all I can say is that ours most certainly works.  Not sure why we can't get it to work on PSpice. 

Kindest
Rosie

Added.  And tell MileHigh that we most certainly have the CSR where you've shown it.  lol

[fuzzytomcat]

Rose,

MOSFETs have 3 pins as you know. From left to right; 1, 2, 3.

If the pin names (gate, source, drain) are a stumbling block for you and those working on the sims, perhaps you can draw up the new as-built apparatus by designating only the pin numbers and where they are connected.

I truly can not wrap my head around the problem you are having as you are describing. What the pin names are, and how the MOSFET is represented symbolically, is immaterial. All you need do is tell us how the MOSFETs are physically connected in the circuit, and if you wish to use pin numbers (i.e. 1, 2, 3) then please do. Use a box with 3 labeled pins on it if that works for you.

You really are stumbling on something that is an unnecessary self-imposed block to conveying this important information.

.99

Hi Poynt,

I put together a package of images for the electronic students here at Over Unity that don't understand the actual configuration details and standard nomenclature on one of the three (3) electronic components used in the experimental device(s) construction or build in this thread.

As you and the small few experienced experimentalist posting here know there is a connection between the Drain (D) pin #2 and the Mosfet back plane is also noted.

The use of any type of CONDUCTIVE paste between the "Mosfet Body and Heat Sink" is never recommended as you also know but others may not, and using a "SIL Pad or Mica" something as a INSULATOR is required for 100% isolation between the Mosfet Body and Heat Sink.

Best Regard's
Glen