QUESTION: operational lifetime circuit/system

[ozgur84]

Hello all,

I want to design a basic circuit which measure the usage time of another circuit. Basically, the circuit should measure the on time of the other circuit when it is powered and it should count the hours of operation (and keep the value when circuit is not powered. it should go on counting where it stopped after the circuit is powered again). As soon as the desired operation time is reached let's say it should flash a red LED to indicate the user and a button can reset the timer after the part is replaced with the new one . Could you give me some keywords for my google search or some examples? I am trying to avoid using microcontrolers or highly specific systems because the main circuit is pretty basic.

Cheers!

 

[ronsimpson]

I am using a "hour meter" that comes from digikey.com . Search for hour meter. Digikey only has 129 different types.

 

[ozgur84]

I am using a "hour meter" that comes from digikey.com . Search for hour meter. Digikey only has 129 different types.

Thanks ronsimpson, I did not know the name of these meters. I will pick one from digikey.

 

[KeepItSimpleStupid]

I did find one https://www.google.com/url?sa=t&rct...HgvgCgJzuj3erFk6RRte7QA&bvm=bv.55123115,d.eW0, but could not find where to purchase it.

Generally, there isn't an exact time for say preventative maintenance or replacement and therefore non-resetable meters are the norm. I had to replace a lamp every 1000 hours or so because the spectrum changed too much by that time.

Determining "ON" can be different for each device.

 

[MikeMl]

I have one similar to these in both airplanes. There is a NO pressure switch in an oil galley on the aircraft engine. The "running-time" commences when the engine is started (presence of oil pressure). I do oil changes at specified intervals...

 

[ozgur84]

I also saw that the hour meters are used on motorcycles for similar purposes like aeroplanes... But I am still thinking about a circuit which can do the job. A voltage regulator, a crystal oscillator and a chip which has a small amount of memory and capable of counting could work but how?

 

[KMoffett]

The problem with the standard hour-meter is ozgru84's requirement for a set-able end-count and indicator LED.

Ken

 

[alec_t]

Sounds like a job for a micro + LCD + key-pad. Avoiding using a micro would increase circuit complexity.
How accurate does the time measurement need to be?

 

[Nigel Goodwin]

Sounds like a job for a micro + LCD + key-pad.
How accurate does the time measurement need to be?

It doesn't need to be that complicated - just a micro-controller, an LED, and a press button switch (to reset it).

Assuming accuracy doesn't need to be exceptional, a PIC with it's inbuilt oscillator would do the job, if greater accuracy is required pick one with TMR1 capable of running from an external 32KHz crystal, or use a crystal as the clock for the PIC.

But essentially it's a job for a micro-controller, not for standard chips.

 

[ozgur84]

It should not be so accurate. I am not looking for a circuit like +/-15sec accuracy per year. I was trying to avoid using a microcontroler or an LCD because the project itself is quite retro-looking. I can think about something based on Arduino or the Atmega or Pic stuff but I want to keep the project quite retro looking as i said...I might use a very tiny motor and a old gauge ( like the one below) from an old casette player and a microcontroler to turn the motor on every hour .

 

[alec_t]

How retro? Do you want to avoid all ICs, or any transistor-based solution?

Edit:
One option, avoiding a micro, would be a CD4060 clock/counter chip, possibly followed by further counter ICs depending on the total time you want to measure.

 

[ozgur84]

How retro? Do you want to avoid all ICs, or any transistor-based solution?

Edit:
One option, avoiding a micro, would be a CD4060 clock/counter chip, possibly followed by further counter ICs depending on the total time you want to measure.

Inside of the enclosure is not important, as long as the dial/gauge has the proper look.

 

[dr pepper]

You could use an old fashioned moving coil meter with the pwm function within a lot of pic micro's.
You'll probably need to use the eeprom to keep track of hours during power down.

 

[Brevor]

This is very suprising, I just finished a project like this. In fact I just installed it today. It's a device that counts how many hours an air circulation blower runs and lights an led when it's time to replace the filters. However it uses a microcontroller.

 

[ozgur84]

You could use an old fashioned moving coil meter with the pwm function within a lot of pic micro's.
You'll probably need to use the eeprom to keep track of hours during power down.

Hello again,

Sorry, because I moved in another city and changed my job, I could not follow the post last week. I think I will use an Atmel Atmega as a basic version on a self made Arduino pcb and an eeprom and for the interface an old dial from a cassette player with a stepper motor.

Dr. Pepper could you give an example about a coil meter?

This is very suprising, I just finished a project like this. In fact I just installed it today. It's a device that counts how many hours an air circulation blower runs and lights an led when it's time to replace the filters. However it uses a microcontroller.

Hi Brevor, could you explain your project with more details?

Cheers

 

[dr pepper]

Hope the move went ok and the new job/location works out.

I'm sure you know what I mean:

https://www.google.co.uk/imgres?img...a=X&ei=GdFyUp3oNvCN4gTdnIDgAQ&ved=0CB0Q9QEwAA

 

[ozgur84]

Hope the move went ok and the new job/location works out.

I'm sure you know what I mean:

https://www.google.co.uk/imgres?imgurl=https://upload.wikimedia.org/wikipedia/commons/f/f2/VU_Meter.jpg&imgrefurl=http://en.wikipedia.org/wiki/VU_meter&h=426&w=728&sz=31&tbnid=7ghT0mK9pJJ69M:&tbnh=70&tbnw=120&prev=/search?q=vu+meter+photo&tbm=isch&tbo=u&zoom=1&q=vu meter photo&usg=__zvv0NkrT-ZzCVAPkIsYr7ON6x_c=&hl=en-GB&sa=X&ei=GdFyUp3oNvCN4gTdnIDgAQ&ved=0CB0Q9QEwAA

Thanks for the good wishes Yes I know! and it is a rather good idea!! it will look perfect on the dashboard. I should educate myself about eeproms and how to use with atmega ) cheers!

I will post the details here when I start, I should order some parts now.

 

[dr pepper]

I found on a fork lift truck a while back what looked like to be a fuse, it was connected accross the ignition supply via a resistor, it was actually an hour meter in a fuse case, it looked a bit like a thermometer with a chemical rising inside a thin capilliary within the device.
Such a device wouldnt bring an led on at a predetermined time so isnt much use to you.

 

[Brevor]

Hi Brevor, could you explain your project with more details?

Hello Ozgur84,
Not really much to explain, Where I work we have several "air handlers" large blowers that circulate the air.
The devices I made simply connect to the blower motor power source (120 V 60Hz) and counts how many hours the blower motor runs. At 500 hours it lights an led to alert a maintenance worker to replace the air filters.
When the filters are replaced the maintenance worker pushes a reset button that turns off the led and resets the hour counter to zero. It uses a Microchip PIC 12F629 to count the runtime. It saves the registers to EEPROM in the event of a power failure and then restores them when power returns.

 

[KMoffett]

I found on a fork lift truck a while back what looked like to be a fuse, it was connected accross the ignition supply via a resistor, it was actually an hour meter in a fuse case, it looked a bit like a thermometer with a chemical rising inside a thin capilliary within the device.
Such a device wouldn't bring an led on at a predetermined time so isnt much use to you.

That is a mercury timer. They used to use them in a lot of medical and projection devices to indicate maintenance cycles. They run on DC through a current limiting resistor. The mercury is in two columns, separated by a tiny drop in electrolyte, in a thin glass tube. The mercury is eroded from the end of one column and deposited on the end of the other. This moves the drop of electrolyte along the scale at a known rate. About as rare now as mercury switch thermostats.
https://www.amazon.com/Ushio-USHIO-UXR-MT-Mercury-Timer/dp/B004MAFEP0
Ken