📈 Timing & Counting Lab
Two instruments, one timing chain. 555 Timer mode: a live scope showing the capacitor voltage sawing between the ⅓ and ⅔ VCC thresholds while the output squares off above it — drag R₁, R₂, and C and verify the frequency formula in real time, or switch to monostable and fire single pulses. Counter mode: all four counters — 4-bit binary, BCD, up/down, and Johnson — with an LED state row, decimal readout, and scrolling timing lanes that reveal frequency division as it happens.
Auto-clock (free-running)
💡 Guided Explorations
1. Verify the formula: 555 astable, R₁=10k, R₂=47k, C=10µF — the readout should confirm ≈1.4 Hz. Halve C and watch frequency double: pure proportionality. 2. The duty-cycle law: make R₁ huge and R₂ tiny — duty approaches 100%; reverse them — it approaches (but never reaches) 50%. 3. One clean pulse: switch to Monostable and fire the trigger repeatedly — every pulse is identical width T = 1.1·R₁·C no matter how you mash the button. 4. Two views of one circuit: Counter mode, 4-bit binary, auto-clock — read the LED row as a number while the lanes below show Q0–Q3 dividing by 2, 4, 8, 16. 5. The decade reset: BCD mode, single-step past 9 — it snaps to 0, never showing 10–15. 6. Reversal: Up/Down — count to 5, flip DIR, and watch the lanes' pattern mirror. 7. The wave: Johnson mode, auto-clock — a wave of 1s washes across the LEDs and back, one bit changing per clock: 8 states from 4 flip-flops, glitch-free by construction.