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Dear all,

I am new to LTspice and electricity(my dad is my teacher), I was looking on google how to add a photo transistor. The only useful thing I found was to add a Photo coupler. I tried this in a circuit with a n-Channel mosfet and it was successful. But when I want to change the parameters of the Photo coupler it gives me a notification it is not possible. How can I override this?

Many thx. for your feedback,

Kr,

Renato

I am new to LTspice and electricity(my dad is my teacher), I was looking on
google how to add a photo transistor. The only useful thing I found was to add
a Photo coupler. I tried this in a circuit with a n-Channel mosfet and it was
successful. But when I want to change the parameters of the Photo coupler
it gives me a notification it is not possible. How can I override this?

This is likely a MS-Windows problem, but you haven't given us nearly
enough information to say for sure.

You probably put a file in a directory owned by Windows (perhaps a
subdirectory of C:/Program Files/ where the LTspice program itself
is), and Windows doesn't let you modify it. Morale: Never put your
schematics, models, symbols, subcircuits, or netlists under the
Program Files folder.

If your interpretation of "it is not possible" differs from mine, then
maybe I am not on the right track. If so, you will have to give us a
lot more information. Or, upload your file(s) as instructed on this
group's main page and show us what didn't work.

Regards,
Andy

--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:

I am new to LTspice and electricity(my dad is my teacher), I was looking on
google how to add a photo transistor. The only useful thing I found was to add
a Photo coupler. I tried this in a circuit with a n-Channel mosfet and it was
successful. But when I want to change the parameters of the Photo coupler
it gives me a notification it is not possible. How can I override this?

This is likely a MS-Windows problem, but you haven't given us nearly
enough information to say for sure.

You probably put a file in a directory owned by Windows (perhaps a
subdirectory of C:/Program Files/ where the LTspice program itself
is), and Windows doesn't let you modify it. Morale: Never put your
schematics, models, symbols, subcircuits, or netlists under the
Program Files folder.

If your interpretation of "it is not possible" differs from mine, then
maybe I am not on the right track. If so, you will have to give us a
lot more information. Or, upload your file(s) as instructed on this
group's main page and show us what didn't work.

Regards,
Andy

Dear Andy,

Thx. for your reply, I indeed saved the library files under program files. When I right click on the photo coupler it gives me following message "High density mounting photo coupler This component cannot be edited". The strange thing is that all other components can be edited and they are saved in the same library. I will upload the file on the group main page to make it more clear.

Many thx. for your feedback,

KR,

Renato

--- In LTspice@..., "mase723777" <mimmo_renato@...> wrote:

Dear all,

I am new to LTspice and electricity(my dad is my teacher), I was looking on google how to add a photo transistor. The only useful thing I found was to add a Photo coupler. I tried this in a circuit with a n-Channel mosfet and it was successful. But when I want to change the parameters of the Photo coupler it gives me a notification it is not possible. How can I override this?

Many thx. for your feedback,

Kr,

Renato

Hello Renato,

Nearly all symbols in the LTspice library are intentionally
made as specific symbols. This prevents that users corrupt
their database.

One can modify this symbol to allow to change the parameter
Igain for example.

I have made a new symbol PC817.asy for you. Please try my example.

Files > Temp > PhotoTransWithMOSFET.zip

Its best practice to copy this symbol into every folder where
you have a schematic using this new symbol.

Best regards,
Helmut