555

Not sure what you want with "555". Here are a few common possibilities—tell me which one you’re after or ask for something else.

• 555 timer IC (electronics)

  • Monostable: pulse width t ≈ 1.1 × R × C
  • Astable: frequency f ≈ 1.44 / [(RA + 2 RB) × C], duty cycle = (RA + RB) / (RA + 2 RB)
  • Pinout (typical): 1 GND, 2 Trigger, 3 Output, 4 Reset, 5 Control, 6 Threshold, 7 Discharge, 8 Vcc
  • Useful for: timers, pulse generation, pulse-width modulation, oscillators

• The number 555 in math

  • Prime factorization: 555 = 3 × 5 × 37
  • Divisible by 3 and 5; digits sum to 15
  • In binary: 555 = 1000101011
  • Roman numeral: DLV

• Something else (year, coding, etc.)

If you’d like, I can give you a mini-tutorial or a couple of practice problems for the topic you choose. Which one should I focus on?