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advice about timer? Answered

I need cheap small timer to use in my device ( voltage protector) to use in control of warranty of 3 months, this timer will connect to led and when the time is finish (3 month of real working) the led will off, this timer should calculate the time of electricity working only ( if electricity cut off the timer not calculate the time when there is no electricity)  the timer continue calculate the time of working only is case of electricity is exist.
when the total time of electricity on (exist) reach 3 months the timer will cut off the power on the led so will turn off the led

Tags:timer

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icengiceng

Answer 4 years ago

Or even a smaller device like this one operates on a micro DC current capable of thousands of hours !

electro-chem-timer.PNGEC-Timer.bmp
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seandogue

4 years ago

If I had an old fashioned clock, I could make a poor man's solution quite easily. (and in fact, there are commercial devices used in industry all the time which are essentially just that. They are often installed on systems to determine time of use for proper subsequent system maintenance)

These days, I'd do as other have suggested and use a uC and a current detector.

A current detector in its simplest form is a differential input comparator monitoring the voltage across a very low ohm resistor in the current path of the load.

When current (Ir) flows through R, V=IxR dictates a resultant Vr, which in turn flips the comparator to Logic HI. program says:

Program => If detector pin goes high, count and store to memory

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seandogueseandogue

Answer 4 years ago

poor man's solution =>. Old fashioned motor driven clock.

Plug clock into same power source that will be powered on.

With power off, set clock hands to 12.

Only thing is you have to monitor it on a daily basis. It's fault lies in the fact that it has an 86400 count auto-reset. Stupit circles. ;)

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verence

4 years ago

As iceng said, a small µP powered together with the device. It can measure the run time and store it in an internal EEPROM. Even some 6pin devices can do that.

But to ensure the exact time, you'll have to either add a crystal oscillator or count the mains power wave cycles (50 or 60Hz).

And still.... there is a problem with this idea if you want to use it for warranty. You may trust your counter, but your customer may not. Imagine: a customer brings a device he bought half a year ago. The warranty LED is off (at least 3 months of use) and tells you he used it only for two days maximum - so it's clear (to him) that the device AND the warranty timer must be broken. Fix it for free.... What will you do? Fix it for free - you could have dropped the timer idea from start. Dispute the customer, go to court - good luck with that.

There is a reason for a fixed time warranty from date of sale. It's easy - all you need is the receipt and a calendar.

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iceng

4 years ago

A low cost 2160 hour active power on timer use a low cost uP powered by the electricity you want to measure.

Otherwise A clock and IC counters....