Does anyone know what are the parameters or where i can find them so i can use a PNP transistor - BC557B?

Sorry if this is the wrong place but i'm new here. Thanks in advance

by Magnesiam
March 10, 2014

Hi Magnesiam,

Welcome to CL.

I'm not quite sure of the scope of your question so please excuse me if this covers stuff you already know or if it is too detailed.


To edit device models see:



SPICE parameters for devices have little to do with datasheet specifications. They are much more to do with semiconductor physics and the particular process under which a given device is manufactured at the foundry. Consequently it is not always a simple task to map datasheet information onto the model parameters.

However, if you can find a spice model for your target device, then you can edit the relevant parameters of one of the built-in CL models and use that in your circuit.

So ... what you can do is trawl manufacturers websites for a spice model of the device you want to simulate.

From there you pilfer the parameters that you can use in the CL model and set up the CL model using them (Edit parameters > Edit individual parameters).

In the background, build a test jig like the one in this lively little thread:


or this one:


(tee hee!) to sanity check your CL model against its original datasheet.

For more information please see this thread:


Note that there are some unanswered questions about editing CL model parameters (which may not affect you anyway):


If you want to try to understand more about what the SPICE - and hence CL - parameters mean in diodes, bipolar transistors and MOSFETs, then you might like to have a look at:


with individual slide sets:




For more detailed information about bjt's in particular, have a look at this book:


available from:




Another excellent (and free) book about transistor modelling, go to:


and register to get a copy of:

Definitive Handbook of Transistor Modeling

by signality
March 11, 2014

Yeah I meant BJT sorry. And yes you answered my question. I found the .model and it worked. Thank you very much

by Magnesiam
March 11, 2014

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