Spectrum Software
Industrial Strength Simulation




Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.




Easily Overlooked Features


This section is designed to highlight one or two features per issue that may be overlooked because they are not made visually obvious with an icon or a menu item.

Mouse Panning
There are multiple methods for navigating schematics and plots. Some of these were discussed in the last newsletter. The most powerful of all is the right-click pan. Here's how it works:

This works like sliding a sheet of paper to better see the area you want. Click the right mouse button in the schematic or plot. While holding the button down, drag the mouse in the direction you want to "slide the paper". This moves the "paper" in the direction of the mouse move. It is omnidirectional, works in any mode, is always available, and works on schematics, analysis plots, and in the Shape Editor.

Rotating Parts
Parts can be rotated while being placed or afterwards. To rotate a part during placement, click the right mouse button. During placement the left mouse button is held down. This means you are holding the left button and clicking the right button once for each rotation. There are eight rotations/reflections, so eight clicks will cycle through the entire range of orientations. To rotate a part after placement, click and hold it with the left button and click the right button until you get the orientation you want.

Analysis-Dependent Part Values
Sometimes you may want to use different values for resistors, capacitors, and inductors, depending upon whether you are doing an AC or a transient analysis. This typically occurs when you want to do an open loop measurement. Inserting an inductor into the loop lets you open the loop by changing its value to a value that is so high it effectively "opens the loop". Typically you have a capacitor that allows an AC signal to be injected and an inductor that opens the loop. For AC analysis, you might want the capacitor to have a value of 1000F, and for transient analysis, where you want the cap removed, a value of 1p is needed. For the inductor you might want 1000H for transient and 1p for AC. Here is how it is done:

Assign LVALUE to the inductor VALUE attribute and CVALUE to the capacitor VALUE attribute. Then add these commands to either the schematic or the text area.

.define LVALUE IF(analysis==_transient,1p,1000)

.define CVALUE IF(analysis==_transient,1p,1000)

The variable analysis has different values, _transient, _ac, and _dc, _tf, and _sens, _dynamicdc, depending upon the type of analysis chosen.

The IF statements return 1P if the analysis is transient or 1000 otherwise. Now when you run AC or transient analysis the program automatically provides the desired value for the components. Of course you could do this manually, but the automated system is easier and less error prone, especially if you are planning to do many analysis runs.
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