Re: Mechanical switch

Hi, :

I guess the question would become ''how to describe the physics behavior about eg. ionization in the air in math equations, and cross voltage before/after acring, and so on..."

I am really interested in those topics, but I can't quite know the terminologies of those topics (about arcing, sparking behavior in physics).

I thinks that's the background knowledge required to built-in the model of spice.

If someone could provide any information about this ?

thank you

Best regards.

---In LTspice@..., <kc6ete@...> wrote :

The bounce is less interesting to me than the spark.? Think kettering ignition system.

Re: Current Dependent Voltage Source

#90005

What if I want to input a table of data I measured from a unit?? I have multiple input/output pairs that I want to use.? How would I do this??

Sent from Yahoo Mail.

On Monday, August 1, 2016 11:50 PM, "Andy ai.egrps@... [LTspice]" wrote:

rmoreno.phone?wrote:

? ?"I've tried to understand how to create a current dependent voltage source but am unable to comprehend how to get my simulation circuit to work.? Is there anything available to describe in detail how to do this?"

Yes; there is the LTspice Help page for H-elements (current-dependent voltage sources).? But most of the reference descriptions there are most helpful for SPICE Netlists, and are a little vague about applying the same syntax to schematic symbols.

Assuming that you are using a schematic:

Voltage sources are our "ammeters".? Put a voltage source (probably set to 0V, but could be non-zero if that fits the rest of your circuit) in the branch where you want to sense the current, that will control your CCVS.

Add an H element where you want it.? Then right-click on the H that is by itself.? Edit that field so that it looks something like this:

Vxxx yyy.y

where Vxxx is the name (reference designator) of the voltage source that is the "ammeter",

and yyy.y is the transresistance or gain (in ?volts/amps) that you want.

Andy

Re: Need help to design a transimpedance amplifier

#90007

开云体育

Unlike a conventional op-amp circuit, the capacitance at the summing junction is extraordinarily important for bandwidth and stability. You can discover this through simulation. Likewise, you can use simulation to explore the requirements for gain-bandwidth product and such. Be aware that often, secondary parameters such as input capacitance are NOT included in simulation models unless the model uses actual transistors for the input stage rather than just a behavioral model.

Jim

James Wagner

Oregon Research Electronics

Show quoted text

On Aug 2, 2016, at 8:49 PM, t.obulesu@... [LTspice] <LTspice@...> wrote:

Thanks for your swift response..?

And whatever the maximum current I can detect upto 5V ...that is fine...?
But I am worrying about how to choose the suitable opamp and design parameters....and resolution should be good...

Re: Mechanical switch

#90004

I tried to sign up normally. Its a catch 22.

Show quoted text

On Aug 2, 2016 9:39 PM, "Andy ai.egrps@... [LTspice]" <LTspice@...> wrote:

?

David,

I don't remember now why you didn't have access to this group's webpages.? I think something was preventing you from signing up the "normal" way, so you had to subscribe via email only.

I think you really ought to subscribe the "normal" way, so you can get access to the group's Files.? Over the last 14 years, there have been questions about contact bounce and about modeling arcing (sparks), and files uploaded about them.? I don't remember how completely those questions were answered.? But I think you might benefit from being able to see those files.

Regards,
Andy

Re: Looking for a IDT74CBTLV3253 model.

#90003

Hello Andy

You wrote :
" Perhaps you are using Firefox, and perhaps you asked Firefox to open
the file in LTspice. Don't do that. "

I think you got it.
I have tried (again) the bad manipulation you described and I got
"multiple instances of? flags"

Regards
PhB

Re: Need help to design a transimpedance amplifier

#90002

To?t.obulesu:

I think you don't have a good understanding of the problem you are trying to solve.? You asked this question twice already.? You got an answer before too, which you apparently ignored.? I get the feeling you do not understand what the constraints and the requirements are.? Your expectations are unrealistic.

FYI, this is not a place to help you design your circuit.? We can help with the simulations, once you have a circuit.

Regards,

Andy

Re: Unable to find InstName attribute in LTSpice for mac

#90001

Hello,

I haben't got an answer from Mike so far.?

In the meantime you could start with an existing symbol like?opamp2 from folder [Opamps].?

Open this symbol and then do a "File->Save as" with the new name.

Now modify this symbol and save it.

Best regards,

Helmut

Re: Need help to design a transimpedance amplifier

[email protected]

#90000

Thanks for your swift response..

And whatever the maximum current I can detect upto 5V ...that is fine...
But I am worrying about how to choose the suitable opamp and design parameters....and resolution should be good...

Re: Looking for a IDT74CBTLV3253 model.

#89999

A reply I sent earlier, disappeared (never made it).  Here it is again:

Gunoi Nare wrote:

   "As I said before, opening this file returns the error "Multiple flag.""

You had a bad (corrupt) download.

Perhaps you are using Firefox, and perhaps you asked Firefox to open
the file in LTspice.  Don't do that.

Instead, download and SAVE the file to your disk.  After it has
downloaded and saved, then go to Windows Explorer, find the file, and
then open it in LTspice.

Regards,
Andy

Re: Need help to design a transimpedance amplifier

[email protected]

#89998

Well....Bandwidth required is 1 MHz..
APD biasing voltage is 26-30V.
Photodiode capacitance is 5pF

Re: Mechanical switch

#89997

David,

I don't remember now why you didn't have access to this group's webpages.? I think something was preventing you from signing up the "normal" way, so you had to subscribe via email only.

I think you really ought to subscribe the "normal" way, so you can get access to the group's Files.? Over the last 14 years, there have been questions about contact bounce and about modeling arcing (sparks), and files uploaded about them.? I don't remember how completely those questions were answered.? But I think you might benefit from being able to see those files.

Regards,

Andy

Re: Looking for a IDT74CBTLV3253 model.

#89996

Hello Gunoi Nare

You wrote :
"As I said before, opening this file returns the error "Multiple flag."?? "
A/
I'm talking about A-counter_test;asc?? with "A-" as prefix.
You have never talked about A-counter_test.asc

B/
How do you try to open asc files ? Do you use "Open" in "File"? menu inside LTspice ?
Are you working on Windows 32 or 64 ?

Regards
PhB

Re: Unable to find InstName attribute in LTSpice for mac

#89995

开云体育

I think it is something like control-click or option-click or such.

Jim

James Wagner

Oregon Research Electronics

Show quoted text

On Aug 2, 2016, at 2:28 PM, helmutsennewald@... [LTspice] <LTspice@...> wrote:

Hello,

I rarely use a MAC.?
I have tried now to add to a new symbol, but I also couldn't find a menu to do this.

I have sent an email to Mike, the author of LTspice. Let's see what he will answer.

".... how to add the? to a symbol in the symbol editor of MAC-LTspice."

Best regards,
Helmut

Re: Mechanical switch

#89994

The bounce is less interesting to me than the spark.? Think kettering ignition system.

Show quoted text

On Aug 2, 2016 2:30 PM, "helmutsennewald@... [LTspice]" <LTspice@...> wrote:

?

Hello David,

You could make a bouncing switch with a V-source (PWL) as the control voltage for a switch SW.

You can see a "typical" bouncing switch on the top-left picture.
?

Best regards,
Helmut

Re: libraries for electronic components

#89993

Hi, :

There are some info mentioned in the file?

scad3.pdf

For example, at page.127~131, it says the definitions of BJT's parameters in SPICE.

But it seems this is the stuff belongs to the development of those components, as a user who takes those parts in application, those stuffs to identify those parameters could be a huge challenge and spent-lots-time work.

If this makes you stand back, maybe you could seek a easier way, for example, seek the help from the vendor of those components.

for your reference

Best regards.

?

Re: Looking for a IDT74CBTLV3253 model.

#89992

Modified version of "COUNTER TEST.asc" has been uploaded to Temp, named "COUNTER_TEST_works.asc".

I added the parameter needed to make the "counter" logic device actually count.

Andy

?

Re: Modelling an optoisolator

#89991

Hi, :

The following may be out of topic. But I am really curious about this...(and seeking for help, for those terminologies that I can't find out.)

I have searched the keywords like "led luminous intensity forward current math equation" in google.

But there are not such research results about those "If" through photo diode vs. lightening photons or intensity (whatever it's called) in math equation relations.

Could someone has any concept about this ?

The better is , if by the way the photo detector could be talked about.

Thank you

Best regards.

?

Re: Need help to design a transimpedance amplifier

#89990

That is quite easy. There lot of cmos type opamp with low drift spec. You can have t network on feedback which keep cost down for single opamp design. You also need cap on feedback to keep it stable.

Show quoted text

On 2 Aug 2016 20:24, "t.obulesu@... [LTspice]" <LTspice@...> wrote:
>
> ?
>
> Hello ?guys..
>
> I want to design a trans-impedance amplifier to detect currents of the APD (in the range of 200 nA to 100 micro A).
>
> Could some one suggest me the best IC with less bias current, single supply (+5 V only) and how to design a high sensitive TIA..? (typically, for every 100 nA change in the current, 100 mV voltage should be displayed).
>
>
>

Re: libraries for electronic components

#89989

gomezmemanuel?wrote:

? ?"I need to simulate the following MOSFET in LTSpice: 2sk3577, RJK0632JPD and 2sk1580."

I was going to recommend this: ?Sometimes you can't find a SPICE model for a transistor you want to use.? In that case, try to find an "equivalent" (or acceptable substitute) transistor for the ones you want.

There are ways to generate a SPICE model for a transistor from just the datasheet.? I have not done this myself.

Andy

Re: Looking for a IDT74CBTLV3253 model.

#90023

Gunoi Nare wrote:

? ?"As I said before, opening this file returns the error "Multiple flag.""

You are having a bad (corrupt) download.

Perhaps you are using Firefox, and perhaps you ask Firefox to open the file in LTspice.? Don't do that.

Instead, download and SAVE the file to your disk.? After it has downloaded and saved, then go to Windows Explorer, find the file, and then open it in LTspice.

Regards,

Andy