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From: Jim Thompson on 4 Apr 2010 13:03
On Sun, 04 Apr 2010 08:58:40 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote:

>On Sun, 04 Apr 2010 08:34:53 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote:
>
>>On Sun, 04 Apr 2010 08:02:46 -0700, John Larkin
>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>
>>>
>>>I recall somewhere, maybe in this ng, the procedure for making an
>>>ideal diode in LT Spice. But I can't find it now. Help!
>>>
>>>The ideal diode should be a stock pulldown part. I wonder why it's
>>>not.
>>>
>>>And why can't I change the voltage of one of their pull-from-the-list
>>>zeners? That would sure be convenient.
>>>
>>>John
>>
>>Perfect diode...
>>
>>http://analog-innovations.com/SED/PerfectDiodeForChargerIsolation.pdf
>>
>>Though I'd think one could conjure up a behavioral rendition. I'll
>>think on it ;-)
>>
>
>Sure there is, just open "CompliantParts.SLB" on the Subcircuits and
>Symbols page of my website (it's plain text).
>
>A current source with no reverse current and a finite curvature can be
>thought of as the same as a (nearly) ideal diode.
>
>It's TANH, so all derivatives are there and smooth, so it converges
>nicely.
>
>Just set a transition region and a max current to suit.
>
>I'll generate something more understandable by Larkin when I have a
>free moment :-)
>
>Maybe a symbol with parameters to make it easy :-)
>
> ...Jim Thompson

Maybe not even that complex. Maybe just write your own diode
equation?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

The only thing bipartisan in this country is hypocrisy
From: Martin Riddle on 4 Apr 2010 13:36


"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
message news:8nfhr5dcge88dkrfoprobgpoa7177pn3ih(a)4ax.com...
> On Sun, 04 Apr 2010 08:02:46 -0700, John Larkin
> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>
>>
>>I recall somewhere, maybe in this ng, the procedure for making an
>>ideal diode in LT Spice. But I can't find it now. Help!
>>
>>The ideal diode should be a stock pulldown part. I wonder why it's
>>not.
>>
>>And why can't I change the voltage of one of their pull-from-the-list
>>zeners? That would sure be convenient.
>>
>>John
>
> Never mind, I figured out the ideal diode.
>
> Click the D thing and add a diode to the schematic. Rename it Didl.
>
> Then add a spice directive string nearby...
>
> .model Didl D(Ron=0.1 Roff=1G Vfwd=0)
>
> with whatever values you think are close to ideal. For some reason, my
> sim slows down if I use too low an Ron value. The 0.1 is good enough.
>
> The ideal zener is then just a voltage in series with this diode.
>
>
> I'm doing what the controls guys call a "high select", to create a
> voltage that's the greater of two inputs, to switch my power supply
> from constant-current to constant-voltage mode. I did a clever thing
> with two switch elements, but it did funny things sometimes and was
> too hard to think about.
>
>
> John
>
>

Someone has a patent on I think its on the fly C-mode to V-mode
switching, you might want to look that up.
Hint, they are on LI NY.

Cheers



From: John Larkin on 4 Apr 2010 15:27
On Sun, 4 Apr 2010 13:36:49 -0400, "Martin Riddle"
<martin_rid(a)verizon.net> wrote:

>
>
>"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
>message news:8nfhr5dcge88dkrfoprobgpoa7177pn3ih(a)4ax.com...
>> On Sun, 04 Apr 2010 08:02:46 -0700, John Larkin
>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>>
>>>
>>>
>>>I recall somewhere, maybe in this ng, the procedure for making an
>>>ideal diode in LT Spice. But I can't find it now. Help!
>>>
>>>The ideal diode should be a stock pulldown part. I wonder why it's
>>>not.
>>>
>>>And why can't I change the voltage of one of their pull-from-the-list
>>>zeners? That would sure be convenient.
>>>
>>>John
>>
>> Never mind, I figured out the ideal diode.
>>
>> Click the D thing and add a diode to the schematic. Rename it Didl.
>>
>> Then add a spice directive string nearby...
>>
>> .model Didl D(Ron=0.1 Roff=1G Vfwd=0)
>>
>> with whatever values you think are close to ideal. For some reason, my
>> sim slows down if I use too low an Ron value. The 0.1 is good enough.
>>
>> The ideal zener is then just a voltage in series with this diode.
>>
>>
>> I'm doing what the controls guys call a "high select", to create a
>> voltage that's the greater of two inputs, to switch my power supply
>> from constant-current to constant-voltage mode. I did a clever thing
>> with two switch elements, but it did funny things sometimes and was
>> too hard to think about.
>>
>>
>> John
>>
>>
>
>Someone has a patent on I think its on the fly C-mode to V-mode
>switching, you might want to look that up.
>Hint, they are on LI NY.
>
>Cheers
>
>

Power supplies with separate voltage and current set pots have been
around for 50 years or so, so there's nothing fundamental about this.
Are there still any power supply companies on LI?

About LT Spice: where the heck is the "draw" menu? And why does it
keep moving my schematic around in the view window, jamming it against
the left and right edges at random?

John

From: Helmut Sennewald on 4 Apr 2010 15:54
> About LT Spice: where the heck is the "draw" menu? And why does it
> keep moving my schematic around in the view window, jamming it against
> the left and right edges at random?
>
> John


Hello John,

This "draw" menu is in
Edit->Draw

You can switch off the automatic scroll-view in the
Control Panel -> Drafting Options

Best regards,
Helmut


From: John Larkin on 4 Apr 2010 16:35
On Sun, 4 Apr 2010 21:54:22 +0200, "Helmut Sennewald"
<helmutsennewald(a)t-online.de> wrote:

>> About LT Spice: where the heck is the "draw" menu? And why does it
>> keep moving my schematic around in the view window, jamming it against
>> the left and right edges at random?
>>
>> John
>
>
>Hello John,
>
>This "draw" menu is in
> Edit->Draw
>


Ah, cleverly hidden. Thanks.

John

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