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Iain Wilkie

United Kingdom
960 Posts

Posted - 04 Sep 2008 :  09:57:49  Show Profile  Visit Iain Wilkie's Homepage  Reply with Quote
I am evaluating the EasySpice Demo. I have selected a 2NAND gate that I want to operate from 10 volts but there seems to be no way of selecting this. Also I have PNP transistor with its emmitter tied to +5 Volts and the base connected via a resistor to a pulse source. If I look at the base it is switching between =5 and 0 volts.... surely this should only go between +5 volts to about +4.3 volts ????

On the transistor problem... just noticed the following... the PNP device in the spice lib (2N2904)has the following connections...
symbol emitter is marked as a gate (g)
symbol base is marked as a drain (d)
symbol colloector is marked as a source (s)

Semmes to think this PNP transistor is a FET with mixed up connections. Also I selected the NPN transistor (2N2222) and find that its base and collctor connections are crossed over !!

I have to say I am very new to this and not sure wether I am confusing myself as to how all this is meant to be used.

More ..... !

Ok took a PNP transistor from an example (BC556B) which is PNP, connected its emitter to +5v fixed votage and its collector through 1k to ground, then its base is tied to a 5 volt pulse generator via another 1k resistor. Now unless I am loosing my marbles I should see a pulse train on the base of about +5 to about +4.3 or so volts. Nope... +5 all the way down to zero, the same as the output of the pulse generator on the other side of the base resistor. Also nothing on the collector. I can "probe" the 5 volt supply line and the pulse generator output and all looks good, its as if the base emmiter is not being seen as a diode junction.

Maybe its time for me to give up

Edited by - Iain Wilkie on 05 Sep 2008 21:20:08

Peter Johnson

United Kingdom
459 Posts

Posted - 11 Sep 2008 :  10:48:33  Show Profile  Visit Peter Johnson's Homepage  Reply with Quote
Sorry about the slow response. This shouldn't be happening. As it's the demo you can't save the file, but you should find a <filename>.net file associated with the design, as this is used to pass data to the simulator. Please send a copy of that and a screenshot of the circuit into support, and it will be checked out.

If you're using V12, it's also possible that the libraries are inadvertently picking up the wrong symbol because of the revised way they work. There's a new FAQ about this under [Technology], [Frequently Asked Questions] from the main site. Look for the red star!
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