About the simulation
DC resistors, LEDs, diodes, ideal switches, copper, wire links and meters. Open switches disconnect their leads; closed switches have zero resistance. Ammeters close a circuit in series; voltmeters draw no current. Ideal parallel conductors can have indeterminate current splits. LEDs and diodes use approximate forward thresholds with 20 Ω and 1 Ω slope resistance respectively; reverse current is blocked. Diodes default to 0.7 V. The gate and flip-flop ICs use an HC-style electrical approximation: high-impedance inputs, 2–6 V supply, approximate LOW/HIGH thresholds at 30%/70% of VCC (25%/75% near 2 V), and 50 Ω output drivers. Floating inputs read X; undefined or unpowered outputs are undriven. The 74x90 uses LS-style input thresholds (LOW ≤0.8 V, HIGH ≥2 V) and a 4.75–5.25 V supply; its output drivers are approximate. Flip-flops and counters respond to wired clock edges in Simulate mode and store their state. Reset/preset inputs act immediately in either mode. Power loss clears stored state to X. No propagation delay, setup/hold timing, switch bounce, input clamp diodes, quiescent IC current, reverse breakdown, damage or thermal models for digital parts. Analogue time simulation preserves capacitor voltage across switch operations and updates current, voltage and stored energy as time advances. Live time mode supports analogue parts and LM741s; digital ICs use the DC logic mode. An isolated ideal capacitor retains charge; no capacitor leakage, ESR or dielectric losses are modelled. LM741 circuits support DC, small-signal AC and backward-Euler time analysis. The one-pole analog approximation includes finite gain, bandwidth, slew, input/output resistance, output swing and current limits. It does not model offset-null pins, temperature, noise, recovery from overload or device damage. Its parameters describe a typical educational approximation, not a transistor-level SPICE macromodel. 74HC08 datasheet.