Question

Circu Answer t Analysis Security Alarm 14-Operational Ampifiers and 555 Tmers 20 uestions based on the circuit below: 1. How is the 555 timer used? Does resistor RI and transistor QI set the timing function of the cirecuir? How long does the 555 timer keep the relay latched? 3. 4. How is the circuit triggered? 5. Which process triggers the 555 timer? SPEAKER S1 RESET K1 NO R2 NC R6 A5 01 SIGNAL SOURCE 555 TIMER A1

Answer 1

(1) The 555 timer is an integrated circuit ( chip) used in a variety of timer , pulse generations, oscillator applications . the 555 can be used to provide time delays as an oscillator and flip- flop element . derivatives provide two (556) or four (558) timing circuits in one package. The 555 can be used to provide 50 KB. (4)The 555 timer is designed unusually to give a positive output through a control over its reset pin.usually the timer ic 555 is triggered by applying a negative going pulse to its trigger pin 2 . ( 5) A 555 timer can be used to create a schmitt trigger which converts a noisy input into a clean digital output .the input signal should be connected through a series capacitor which then connects to the trigger and threshold pins.