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Timing Circuit Guidance

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Hi Chaps, I am trying to design a noise protection system for use at work. I have already bought a noise level monitor, which has a 5vdc 4.4mA output, from this i have also got a AC remote relay. This in itself would be ok but when the noise level reaches a certain level i want the warning lights which the above powers to stay on for a time period for example 10 minutes, so that the lights are not flashing on and off constantly, due to anomalies in the sound level. I have looked at the timing circuit threads on here but the main question is , how can i incorporate a timing circuit to be powered on a single phase 230Vac supply.
Cheers for any help tom


You could use a 555 timer as a one shot, 10 minutes might be too long for reliability though.
555 Timer/Oscillator Tutorial
Above is a link to a good 555 timer tutorial which includes a one shot circuit and shows you how to calculate the resistor and capacitor needed for various time delays.
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