555

Not sure what you want with 555. Do you want help with:

• Electronics: the 555 timer IC (astable/monostable, key formulas)

  • Quick reference: f ≈ 1 / [0.693 (RA + 2 RB) C] for astable
    • t_high = 0.693 (RA + RB) C
    • t_low = 0.693 RB C
  • Monostable: pulse width t = 1.1 RC

• Mathematics/Number theory: properties of 555

  • Prime factorization: 555 = 3 × 5 × 37
  • Divisibility: divisible by 3 and 5 (sum of digits is 15)
  • Other bases: binary 555 = 1000101011, hex 0x22B

• Other contexts (Roman numerals, area code, etc.)

Tell me which topic you want, and I’ll tailor a quick explanation or a practice problem.