We have a filter outlet nex to the sink that keeps getting left on. People start filling a jug and get distracted and walk away. The old filter (that died) beeped when water flowed through it.I want to make somthing to duplicate that. I was planning on using a old phone charger as a power supply. I found a coffee maker flow meter on amazon for $5. not sure if any voltage comes out when it's not turning tho. And I was going to use a old motherboard speaker, but not sure how to make it beep. Thought about using a continuous beeper, but that sounds like it would make constant noise like my home made continuity testet. how do I make it beep. Do I need a 555 timer or is there an easier way? Can I use the mob speaker or do I need a buzzer? Will the flow meter work as intended, or will it put out constant voltage that goes up with flow, and can that be corrected with a resistor? This is the sensor. http://www.amazon.com/gp/aw/d/B00LZJXY3U/ref=mp_s_a_1_1?qid=1437768292&sr=1-1&pi=AC_SX110_SY165_QL70