Hi, I've been building circuits with my son sometimes using a 555 timer and wondered if this could sort my predicament? The inbuilt timer has failed in the starter for my Dust extractor 380V, no neutral available as is. When the 3Hp motor is switched off a second contractor should switch on to activate a smaller motor for about 30 seconds to shake the dust off the filters. The manufacturer wants about £500 for the timer unit and my electrician says that it can't be done any other way, That doesn't hold with my belief system.