The fifth kit in the How Things Work series. A car reverses towards a wall — and beeps faster the closer it gets. You build such a parking sensor from transistors: four ultrasonic sensors ping in turn, a counter measures the echo time in centimetres, a comparator picks the zone, and the screen shows the car, arcs at every sensor and digits to the nearest obstacle; the buzzer is silent, beeps slowly, fast or without pauses. New CMOS 4000 chips after the Texas Instruments datasheets — the CD4013 D flip-flop, the CD4017 counter, the CD4072 OR, the CD4585 comparator — plus the CD4011, CD4029, CD4511. How a sensor is calibrated is in the kit too. A standalone kit. 4,006 transistors.
The introduction and lessons 0–1 are free; the rest opens after purchase.
4 SENSORS · 7 CHIPS · 4,006 TRANSISTORS