hi i need do it a Electronic circuit for the led of the airbag for itv inspection. i have 555 chip but i need someone that calcule the value of the condensers and the resistances and the scheme for this. i need when i turn on the key the time of the airbag light is light for a 10 secons + -.if i need put 12v in 5v i have L7805cv for this bu i think that the 555 can work 5-16v,can someone help me whitc this.