pcb

Calculates timing parameters for the ubiquitous NE555 / LM555 timer IC in astable (free-running oscillator) and monostable (one-shot pulse) modes. In astable mode, computes frequency, period, duty cycle, and HIGH/LOW durations from R1, R2, and C using f = 1.44 / ((R1 + 2·R2) · C). In monostable mode, computes pulse width from R and C using t = 1.1 · R · C. Standard 555 astable duty cycle is always >50%; for 50% duty cycle use a diode across R2. Useful for generating clock signals, PWM, delays, and debounce circuits. Chain from ohms_law for power calculations or resistor_color_code for component selection.

post/api/timer_555

Request

  • Base URL: https://calc.engineer
  • URL: https://calc.engineer/api/timer_555
  • Auth: none declared

Request body

mode'astable' | 'monostable' required

Operating mode. 'astable' produces a continuous square wave. 'monostable' produces a single timed pulse.

r1_ohmnumber required

Resistance R1 in ohms. In astable mode this is the charge-path resistor between Vcc and the discharge pin. In monostable mode this is the timing resistor.

r2_ohmnumber

Resistance R2 in ohms (astable mode only). Charge/discharge resistor between the discharge and threshold pins. Required for astable mode.

c_faradnumber required

Timing capacitor in farads. Typical values range from 1 pF to 1000 µF. Use scientific notation, e.g. 1e-6 for 1 µF.

Response

Computed result for timer_555

toolstring required
versionstring required
computed_atstring date-time required

Changes

No recorded changes to this operation across all 1 revision of this API.