LTSpice LED parameters

Last August, the anesthesiologist "forgot" to check to see if I was conscious before they cardioverted me. 100J front to back, straight through the chest. I hear I made some references regarding the ancestry of everyone in the room. The next day the doc said "We didn't think you'd remember." Yeah, well... The next time they did it, they checked (and it took another five hours to come out of it).

Depends on where you placed the meter and what type of meter it was.

An HVDC supply is supposed to have a bleed down resistor in it.

Breakdown of such a device as a connector usually comes down to exposed bare node separation distance and their shape. A sharp point will arc 'faster'.

We used old 50 Ohm CB radio coax and connectors on some of our HV designs. The coax has a very high rating and the connector nodes are farther apart then on miniature connectors. (of course).

We had a design where the ouput was about 5 inches deep in the chassis. We used a non-conductive paste and a 5 inch exposed center and sheath of an rf coax cable. So the 50 ohm connector attached to the coax braided shield, and the ceneter "stab" stuck out from that the required 4 point whatever inches to make it hit the HV node down the PVC tube on the HVPS.

It makes for a 'handling safe while energized supply' with the live end of the cable becoming the safety zone.

snip

If you hurt your finger with a 3kV arc (from a de-energized depleting supply), I doubt it did damage to anything other than your pride, unless your HVPS has multi-killowatt drive capacity and storage.

Build a coin shrinker... charge up that bank, and discharge that through yourself instead of the coil. You'd shrink alright.

Hehehehe... fate keeps tryin'. Probably toying with you to lead up to the big event.

You probably think that is something you are holding in your hand though.

Most of us probably have the install files for LTspice squirrelled away someplace, so it isn't going anywhere. It installs and runs fine on Wine under Linux (and probably BSD, Solaris, and Mac, though I haven't checked).

They recently introduced a new major version, LTspiceXVII, to replace the XP-compatible LTspiceIV which is now out of support.

Cheers

Phil Hobbs

At least I haven't been brain dead all my life, AlwaysWrong.

You're the one married to your hairy right hand, AlwaysWrong.

?? LTspiceIV will still "update".

Yep. I have both. If it goes to the cloud, I doubt our local versions will run any new LT models. ...Jim Thompson

Yup. But to download it afresh, you have to pick the "Windows XP (end of support)" option.

Cheers

Phil Hobbs

IIRC there's a native Mac version of LTspice.

Cheers

Phil Hobbs

I'm puzzled. I just tried that and it works fine. Example below.

Jeroen Belleman

Version 4 SHEET 1 880 680 WIRE 128 -96 -64 -96 WIRE 176 -96 128 -96 WIRE 176 -80 176 -96 WIRE -64 -64 -64 -96 WIRE 128 -64 128 -96 WIRE 128 16 128 -16 WIRE 176 16 176 0 WIRE 176 16 128 16 WIRE -64 48 -64 16 WIRE 176 64 176 16 WIRE 224 64 176 64 WIRE 288 64 224 64 WIRE 176 144 176 64 WIRE -80 192 -192 192 WIRE 112 192 -80 192 WIRE -192 208 -192 192 WIRE 176 272 176 240 WIRE 304 272 176 272 WIRE 304 288 304 272 WIRE -192 304 -192 288 WIRE -64 320 -64 272 WIRE 176 320 176 272 WIRE 304 384 304 352 WIRE -64 448 -64 400 WIRE 176 448 176 400 WIRE 176 448 -64 448 FLAG 304 384 0 FLAG -64 272 0 FLAG -64 48 0 FLAG -192 304 0 FLAG 224 64 out FLAG -80 192 in SYMBOL npn 112 144 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res 160 304 R0 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL cap 288 288 R0 SYMATTR InstName C1 SYMATTR Value 1u SYMBOL voltage -64 -80 R0 SYMATTR InstName V1 SYMATTR Value 10V SYMBOL voltage -64 304 R0 SYMATTR InstName V2 SYMATTR Value 5V SYMBOL voltage -192 192 R0 WINDOW 123 24 124 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value SINE(0 10m 1meg) SYMATTR Value2 AC 1 SYMBOL g2 176 -96 R0 SYMATTR InstName G1 SYMATTR Value 1m TEXT 152 -144 Left 2 !;tran 5u TEXT 288 -144 Left 2 !;ac dec 100 1k 100meg TEXT 288 -88 Left 2 !.noise v(out) v3 dec 100 1k 100meg TEXT 248 -32 Left 2 ;G1 behaves like a noiseless 1k resistor

]snip]

In _many_ instances where a G-source is used as a resistor in LTspice, LTspice can't find the operating point because Mikey turns off all current sources during the .OP calculation.

I've taken to modeling noiseless resistors with an E-source to accommodate LTspice users... not as precise as a G-source :-( ...Jim Thompson

In message , John Larkin writes

Last time I reported a problem was with Windows NT.

From the Change log

Version Brian

LED characteristics are quite depending on junction temperature, so you really have to include the thermal resistance from junction to ambient Rth(j-a) into any simulation. While this thermal resistance can be modeled with a constant in a limited temperature range, even this parameter varies with large temperature excursions.

Unfortunately, some manufacturers give their (optical) characteristics at Tj=25 C. Fortunately, some reputable manufacturers give the characteristics at Tj=85 C, so a few iterations in a spreadsheet give more realistic values.

I use it. It's awful, the worst "Mac" app I've ever used. It breaks every rule and standard, replacing them with terrible alternatives.

I seriously think the Wine version is better, though I don't use it enough to have decided definitely.

There's a native version for MacOS, but it doesn't have any provision for a trackpad, it requires a three-button mouse (no menu workaround, no shift/option/control key workaround).

So, you have partial composition in the schematic editor, then the only way to get a working set of component values entered is to text-edit the intermediate file, and it doesn't 'save' as a part of the project when you do...

Am 17.02.2018 um 18:01 schrieb Jim Thompson:

Is it really so hard to write the word "noiseless" after the resistance value?

Gerhard

Try that in any other Spice. That's my beef. LTspice doesn't follow convention. Thus its models won't play elsewhere. ...Jim Thompson

Am 18.02.2018 um 20:01 schrieb Jim Thompson:

Using pspice and then complaining that LTspice does not conform to the "standards"!

May I remind you that we had that problem with Pspice models that could not run on anything else for 20 years or so?

I have extended Jeroen's analysis to employ noiseless resistors or conventional resistors in the emitter or collector. The noise analysis runs fine with either choice.

This gives an excellent display of how the noise from the base appears in the collector but not in the emitter.

Watch the wrap at the end.

Version 4 SHEET 1 880 680 WIRE 176 -48 -64 -48 WIRE 368 -48 176 -48 WIRE -64 -32 -64 -48 WIRE 176 0 176 -48 WIRE 176 0 128 0 WIRE 176 16 176 0 WIRE 128 32 128 0 WIRE -64 64 -64 48 WIRE 128 112 128 80 WIRE 176 112 176 96 WIRE 176 112 128 112 WIRE 288 112 176 112 WIRE 368 112 368 80 WIRE 368 112 288 112 WIRE 176 144 176 112 WIRE 48 192 -64 192 WIRE 112 192 48 192 WIRE -64 208 -64 192 WIRE 176 272 176 240 WIRE 240 272 176 272 WIRE 368 272 240 272 WIRE 448 272 368 272 WIRE 448 288 448 272 WIRE -64 304 -64 288 WIRE 176 320 176 272 WIRE 176 320 128 320 WIRE 368 320 368 272 WIRE 176 336 176 320 WIRE 128 352 128 320 WIRE 448 384 448 352 WIRE 128 432 128 400 WIRE 176 432 176 416 WIRE 176 432 128 432 WIRE 272 432 176 432 WIRE 368 432 368 400 WIRE 272 448 272 432 WIRE 272 544 272 528 FLAG 448 384 0 FLAG -64 64 0 FLAG -64 304 0 FLAG 288 112 out FLAG 48 192 in FLAG 272 544 0 FLAG 240 272 Q1E SYMBOL npn 112 144 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL cap 432 288 R0 SYMATTR InstName C1 SYMATTR Value 10p SYMBOL voltage -64 -48 R0 SYMATTR InstName V1 SYMATTR Value 10V SYMBOL voltage 272 544 R180 WINDOW 0 36 55 Left 2 WINDOW 3 24 16 Left 2 SYMATTR InstName V2 SYMATTR Value 5V SYMBOL voltage -64 192 R0 WINDOW 123 24 124 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value2 AC 1 SYMATTR InstName V3 SYMATTR Value SINE(0 10m 1meg) SYMBOL g2 176 0 R0 WINDOW 3 34 56 Left 2 SYMATTR Value 1m SYMATTR InstName G1 SYMBOL g2 176 320 R0 WINDOW 3 36 57 Left 2 SYMATTR Value 1m SYMATTR InstName G2 SYMBOL res 352 -16 R0 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL res 352 304 R0 SYMATTR InstName R2 SYMATTR Value 1k TEXT -56 -104 Left 2 !.noise v(out) v3 dec 1000 1 10meg TEXT -56 -136 Left 2 ;'G1 behaves like a noiseless 1k resistor TEXT 480 -48 Left 2 ;Data is in nV/rt(Hz)\n2SC4102 2.05nV\n2N2222A 2.83nV \n2N3904 2.21nV