555 Explained - Monostable Mode -

555 working in Monostable Mode (Like an egg timer) Makes one cycle only, from LOW, 0 volts to HIGH that is close to Vcc. ------- TRY -------- 1) Push button one time only to see the cycle - blue in grafics - 2) Increase or decrease values of 100k resistor or 10uF capacitor. Increasing these values will increase the period that it stays HIGH, decreasing these valuea will decrease the period that it stays HIGH. Changes in resistor value is more sensitive. 3) If you hold the button it keeps HIGH until you release. Pin 1 GROUND: To ground. Pin 2 TRIGGER: Starts the 555, is active when LOW (to ground). Pin 3 OUTPUT: Goes from LOW to HIGH - Blue in grafics. Pin 4 RESET: Active when LOW (conected to ground). pin 5 CONTROL: Conected to ground through a 0.01uF capacitor (10nF). Pin 6 THRESHOLD: Monitores the voltage across capacitor conected to pin 7, when it increases and reaches 2/3 of Vcc voltage (2/3 × 6v = 4v in this example) the cycle ends - Green in the grafics. Pin 7 DISCHARGE: To Vcc through a Resistor and to ground through a capacitor. These creates a Resistor-capacitor connection that determines the period that it stays HIGH. Pin 8 Vcc: + Voltage that must be at lest 4.5v and no more than 15v. Sorry for the English, i'm Brazilian. Leave your comment.

published 9 years ago