Data Sheet

Proteus VSM
229
We shall measure two quantities:
The voltage gain of the circuit.
The approximate fall time of the output.
These measurements are taken using the Cursors.
Each graph has two cursors, referred to as the Reference and Primary cursors. The reference
cursor is displayed in red, and the primary in green. A cursor is always 'locked' to a trace, the
trace a cursor is locked to being indicated by a small 'X' which 'rides' the waveform. A small
mark on both the x- and y-axes will follow the position of the 'X' as it moves in order to facilitate
accurate reading of the axes. If moved using the keyboard, a cursor will move to the next small
division in the x-axis.
Let us start by placing the Reference cursor. The same keys/actions are used to access both
the Reference and Primary cursors. Which is actually affected is selected by use of the CTRL
key on the keyboard; the Reference cursor, as it is the least used of the two, is always
accessed with the CTRL key (on the keyboard) pressed down. To place a cursor, all you need
to do is point at the trace data (not the trace label - this is used for another purpose) you want to
lock the cursor to, and click left. If the CTRL key is down, you will place (or move) the Reference
cursor; if the CTRL key is not down, then you will place (or move) the Primary cursor. Whilst the
mouse button (and the CTRL key for the Reference cursor) is held down, you can drag the
cursor about. So, hold down (and keep down) the CTRL key, move the mouse pointer to the
right hand side of the graph, above both traces, and press the left mouse button. The red
Reference cursor appears. Drag the cursor (still with the CTRL key down) to about 70u or 80u