![]() I remember way back in '92 there was a graduate student in electrical engineering I knew took me into a secret back room where he showed me a program that allowed me to basically cut and paste electrical components into a circuit diagram to get a circuit. HelpMeFind needs the support of its members to continue to grow and thrive. He must have been really excited about this program, because I was on my way to being an organic chemist and had zero interest in it. We have added a new premium membership program with a host of new advanced features. Surfing the dope I found this little game posted by Mangetout and I though about how cool it was. Then I thought that it would be really simple to do something like this with electrical components. ![]() I’m not thinking like that computer program the E.E. showed me, I’m thinking more along the lines of one of those fun little kiddie circuit boards with resistors, trasistors and such where you connect everything with wires. MacSpice runs on Intel architecture Apple Macintosh computers. The only difference is, since it is only on the computer, you wouldn’t be limited by the number of components given to you and high voltage and alternating current wouldn’t be problematic. It is compatible with, Berkeley Spice 3f5 but incorporates many improvements to Spice 3f5 from simple bug-fixes to entirely new commands, algorithms and solution strategies. I think it would be really fun to tinker with something like this.įor example: the memory leaks that affected Spice 3f5 have been cured new algorithms have been developed. The probe tip capacitance should be insignificant at 10pF. MACSPICE PROBE PCĭoes it exist? Especially for mac, but I have a PC at my disposal too. Speed and accuracy are still important factors to consider when simulating circuits.And it would be in parallel anyway, so it should add to the net circuit capacitance. With these considerations in mind, the designers of SPICE created a program that could produce reasonably accurate results in a cost-effective manner. They also included many options to allow engineers to customize the accuracy of a simulation.Īs computing power has increased exponentially over the years, so have the complexity of circuit designs being simulated. Also, consider that the broad purpose of circuit simulation is to augment basic hand calculations and predict general circuit behavior. Computing power was very expensive. The simulation of a circuit to the highest degree of accuracy could have taken longer and cost more money than building the actual circuit to see the results. SPICE simulation was created over 30 years go and around that time a typical computer had less power than the average microwave oven did thirty years later. To understand the tradeoff between speed and accuracy in SPICE simulation one must consider a number of factors. SPICE simulation options generally allow the user to gain more accuracy in the results at the cost of the speed of the simulation. OP * perform a DC operating point analysisĪlthough the SPICE models used in a SPICE simulation can greatly affect the accuracy of the results, simulation settings also contribute to varying degrees of accuracy. * Any text after the asterisk '*' is ignored by SPICE We include both netlist and corresponding circuit schematic. Consider as an example the simple voltage divider circuit below. The netlist is a text description of all circuit elements such as transistors and capacitors, and their corresponding connections. Modern schematic capture and simulation tools such as Multisim allow users to draw circuit schematics in a user-friendly environment, and automatically translate the circuit diagrams into netlists. PSPICE is a commercially available program that uses proprietary languages to define components and models.Ī circuit must be presented to SPICE in the form of a netlist. For example, a PLL consists of a voltage-controlled oscillator and divider operating at a high frequency, while other circuit components such as the phase detector, filter and digital control circuitry operate at much lower speed. ![]() One of the most common errors made by even seasoned engineers is confusing a SPICE model with a PSPICE model. Modern analog circuits consist of components that operate at different time constants. Using a SPICE model inappropriately can lead to inaccurate results, or even generate an error in some circumstances. It is important to consider this when using the models supplied with a SPICE simulation package. The quality of SPICE models can vary, and not all SPICE models are applicable to every application. Most commercially available simulators include more than 15,000 different components. Using these intrinsic components as the basic building blocks for larger models, designers and chip manufacturers have been able to define a truly vast and diverse number of SPICE models. SPICE has the ability to simulate components ranging from the most basic passive elements such as resistors and capacitors to sophisticated semiconductor devices such as MESFETs and MOSFETs. ![]()
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