SNAP is a computerized "breadboard" for DC circuits. Includes voltage & current sources, resistors, diodes, bipolar transistors, op-amps. Build circuits, then test them with voltmeter and ammeters. Save and recall previously-built circuits.


SNAP was written by Professor Jerry Hatfield, of Northern Arizona University in Flagstaff. SNAP is an acronym for Simplified Nodal Analysis Program. As Prof. Hatfield said in his paper in the 1988 ASEE Annual Conference Proceedings, pp. 1871-73, "SNAP is a basic, but very easy to use DC circuit simulation program. The device models are very rudimentary, and only DC steady state solutions are provided. Students find that the graphical interface makes the program quick to learn and easy to use." "SNAP allows the student to design an electronics circuit by drawing it on the computer screen with graphics symbols. The program will calculate the resulting DC voltages and currents, which can then be read using a simulated voltmeter and ammeter."

Thus, a student is doing with a computer what would be done in the laboratory of a DC circuits or electronic devices course. Just as in an actual laboratory, in order to connect an ammeter, the circuit must be broken and the ammeter inserted. A voltmeter must have its positive and negative leads connected to two nodes in the circuit. Both ammeters and voltmeters can be connected "backwards", so that they read negative quantities.

SNAP can be used by students to check homework solutions they have done, and to answer "what if" questions. A part value can be changed easily, or the beta of a transistor can be altered, and SNAP will show quickly the effect this change has made on circuit voltages and currents.

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