Medical Filter Day Timer HELP!

Hello, I am a new user to this forum. I work in healthcare. I have an associates from a trade school in electronics. Its been a long time since i've built a cirucuit on a bread board. What I'd like to create is I hope a very simple and cheap circuit.

I want to create a 2 digit LED day counter. It must count from 70 to 0. It must count days accurately. It has to be cheap and no larger than an alarm clock, and it must be wall mountable.

I am a biomedical tech. There are specific medical grade water filters, that must be replaced every 80 days. I want my counter to max out at 70 days to ensure I have time to replaced each filter at different facilities on time. a 10 day buffer if you will.

can this be made with a few cheap components and breadboarded together. I don't mind the "raw circuit" look. it may have some charm for a technicians office.

What power sources are available? If AC power is available, then the unit can run on a USB wal wart, old laptop battery charger, etc. If the unit has to be battery powered, it will take large batteries to power an LED display continuously, and an LCD display will be expansive.

The basic circuit is a timebase, two presettable BCD down-counters, two decoder/drivers, two 7-segment displays, and a pushbutton to reload the count.

The problem is the timebase. If you start with a watch crystal (32.768 kHz) and divide that by 86400 (seconds per day), that is a division ratio of 2.8 billion. That's a lot of divider chips to produce the basic clock rate of 1 pulse per day. Simple in an 8-pin PIC (if you already know how to code), hard in hardware.

A non-normal solution is to use a cheap lamp timer to produce a switched-AC output once per day, adapt that signal, and count that. Also, there are lotsa different kinds of counter and timer modules on ebay.

ak

I didn't look at this https://www.analog.com/media/en/technical-documentation/data-sheets/2956fa.pdf for accuracy.

You can use www.easyEDA.com to layout a PCB and get them made and sometimes assembled.

The MSP430 is probably a good processor to use for that. https://www.ti.com/tool/MSP-EXP430G2ET#tech-docs

You would have to look for an LCD display driver. https://www.digikey.com/catalog/en/partgroup/lcd-display-driver/15378

Search for 4-digit LCD display.

The low power, low voltage make things difficult. But your basically building a watch/timer, so it is possible. There are plenty of LCD time displays.


Whole bunch of stuff: https://www.mouser.com/Search/Refine?Keyword=lcd+display+driver

You might want it to blink at 0.

A simple reset would hopefully be all you would need. You could even make it go negative and blink at 0 or less.

The problem is really low power and low voltage. Not sure if the www.picaxe.com would be low power enough.

These, https://www.maximintegrated.com/en/design/technical-documents/app-notes/5/52.html probably are not cheap.

if you do have a lot of them, why not monitor/reset in a central place. Maybe something that sends a TXT message before they need to be changed. Basically use a general purpose computer. e.g rasberry PI, but just use one of them.

If it's mains powered and you want a big visible display then two of these one on top of the other will give you two digits that are 64mm high. They would only need 4 I/O pins so any processor will manage. May I suggest the once zero is reached, it flashes and starts counting up to show days since it was due to be changed.

Mike.
Edit, it could be easily built using a bread board, an Arduino Nano and some male to female jumper wires.

how many places are we talking about?

Actually you could probably keep track of which ones need changing with an excel spreadsheet.
You have the function =today(). You can easily convert the day today()-installed date and sort by that column.

KeepItSimpleStupid said:

how many places are we talking about?

Actually you could probably keep track of which ones need changing with an excel spreadsheet.
You have the function =today(). You can easily convert the day today()-installed date and sort by that column.

Click to expand...

He could scratch marks on the wall but I think he wants to play. And, he's a tech.

Mike.

e.g.

Here https://www.alibaba.com/product-det...0.7724857.normal_offer.d_title.486b25f7OVUJ8S is a possible display.

You might want a low battery indicator. See page 1 of the datasheet. https://www.analog.com/en/products/lt6700.html

epaper or E-ink displays are even lower power. See https://www.embeddedartists.com/products/1-35-inch-memory-lcd-96x96-px/ The Kohl's price displays are e-paper.

I am in the group suggesting creating a recall list in MS Excel. I would just write a macro in Excel and you just enter the days you want for recall. Don't have Excel? The same can likely be done in Open Office using Calc. That or use MS Access and do the same. Open Office also has an equivalent of MS Access. Just create a data base of all your filters plus any additional data like locations and special remarks or comments. Guessing you use a laptop for work so it's all right there. For possible sample code I would Google "Create Calibration Recall List" in either Excel or Access. Those are the more common over the Open Office free equivalents. Anyway I would just use a software solution before building a counter hardware circuit.

Ron

Got an old smartphone?
Find a tiimer app.

How about using the calendar function on Outlook? Send yourself a reoccurring appointment for each filter. Repeat every 10 weeks. Send the meeting invite to your whole team so everyone gets notified in case of a vacation. No risk of resetting with power failure. No risk of some bumpkin pushing the Reset button.

Reloadron said:

Anyway I would just use a software solution before building a counter hardware circuit.

Click to expand...

That quickie sheet was done in LibreOffice. I would at least add some conditional formatting e.g. RED overdue and yellow - within 10 days.
https://wiki.documentfoundation.org...ice_Calc._Conditional_formatting_guide_EN.pdf

Knowing how many locations would help. You could add some sort of proximity field, maybe. You can sort by bldg, room, floor etc. Maybe even the time of day

I think there is a "note" type of function, where when you hover over a cell, you get specific information.

You can get fancy and add a button macro to do the sort or just manually do it.

This can be an exercise as well. I might try a picaxe and an I2C LED or LCD display.

Here https://ww1.microchip.com/downloads/en/DeviceDoc/DS-22238b.pdf is an I2C clock calendar. That project might be able to run off a USB wall wart and a backup battery.

The trick would be a device similar to a watch.

I think this method is very do-able with minimal skills.

KeepItSimpleStupid said:

That quickie sheet was done in LibreOffice. I would at least add some conditional formatting e.g. RED overdue and yellow - within 10 days.
https://wiki.documentfoundation.org...ice_Calc._Conditional_formatting_guide_EN.pdf

Knowing how many locations would help. You could add some sort of proximity field, maybe. You can sort by bldg, room, floor etc. Maybe even the time of day

I think there is a "note" type of function, where when you hover over a cell, you get specific information.

You can get fancy and add a button macro to do the sort or just manually do it.

This can be an exercise as well. I might try a picaxe and an I2C LED or LCD display.

Here https://ww1.microchip.com/downloads/en/DeviceDoc/DS-22238b.pdf is an I2C clock calendar. That project might be able to run off a USB wall wart and a backup battery.

The trick would be a device similar to a watch.

I think this method is very do-able with minimal skills.

Click to expand...

There you go and I like the color change beyond a date due.

Ron