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Relay timer? Answered

i asked this question in forums before i knew about this so sorry for the copy. i hope someone can answer this here. i am currently engaged in a project where i need to create a count down timer relay controller. i was thinking of using a digital alarm clock as part of my goal is to have the display visually counting down, but i don't know of any that have a count down feature. i want the timer to power a relay to turn a string of IR emitters on for several seconds. i have a digital kitchen timer that counts down, but im not sure if it will work. i would like to use the power to the buzzer to activate the relay but there is no stable current there, it only Emits several beeps in quick succession(when i meter it, it comes out to about . volts). this is why the alarm clock would be better. i was hoping to use an electromechanical relay but i don't think it will work. does anyone know of another relay that will trigger with this kind of input?



8 years ago

555 is a small microchip that allows you, with a little soldering and a scattering of basic additional components, to generate either one long pulse or constantly running pulses

google for the datasheet which also has the formulas for working out time delays, frequency, pulse length, etc, and some example circuits


9 years ago

kitchen timer> signal transistor >"555 one-shot" > transistor > relay.


Answer 9 years ago

im not exactly sure what the 555 one shot is. or why i would need the 555 if i already had the timer. can you explain a little?