This be the circuit sets the time to model is simple,at can fix the time had long ago and have tall good accuracy. By use pillar equipment be IC CA3140 for fix time mouth and NE555 perform sound electric bell origin. By we can fine time value done to a turn VR1 can fine since 10 second arrive at 3 hour. When the time expires will have an electric bell that a loudspeaker. For the equipment that should choose specially. Be C1 100uF 16V values should are a kind Tantalum. Because tall quality more Electrolytic. The moderately but if no enough replace can sir. Request friends have fun the circuit sets the time this please sir.
Simple Timer by CA3140 & NE555