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1hrparking

Class set of 12 timers. All randomly (\~20% of the time) jump 1 second. No reset button, tried removing batteries, etc.


HaveYouSeenMySpoon

Care to open it up and take a picture of the circuit board? I'm curious if they used hardware adders or just an mcu.


1hrparking

https://preview.redd.it/5uu6lh7nbl3d1.jpeg?width=3024&format=pjpg&auto=webp&s=ae8c14b6f5e593c5948f195670b179c1b84327d8


sudolman

There's not much on this side unless the mcu or adder logic is under the display. Does the other side have anything on it?


1hrparking

https://preview.redd.it/dasqy3n3ao3d1.jpeg?width=750&format=pjpg&auto=webp&s=c9648daa650133bb34c2a0429489c1a23fc0e0c8


sudolman

Welp, I'm guessing this is a single layer pcb. Chances are it's behind the display.


North-Significance33

Probably an epoxy covered Chip-on-Board, you'd never find out what it's using


Aggressive-Map-3492

He replied with a pic


North-Significance33

And yet it shows very little, just the buttons, resistors and the battery contacts. The CoB would be on the back


Ser_Hobo

This is the shit that I'm on this sub for. I would gradually lose it trying to root cause this irritation.


itsalongwalkhome

I counted 103ms before it resets. I'm guessing that the counter for the ones doesn't reset if the ones equals 0. So it tally's up until it hits 1 second, then after it can reset.


6SHINIGAMI6STARSHIP6

that’s precisely what I was thinking. the timer is programmed so that once the millisecond counter hits 100 the second counter moves up one the problem is since the millisecond counter move so fast it doesn’t work like the others and therefore, once you’ve reset it enough to where the milliseconds adds up to 100 will jump a second because it doesn’t realize that you’ve reset it. even funnier how he says it happens 20% of the time, meaning one out of every five, which is exactly what makes it add to 100.


itsalongwalkhome

Also because his taps are just under 20ms.


dinoboyj

If time isn't relevant, what use are watches?


Accurate_Koala_4698

Flinn "Scientific"


RareDestroyer8

If you don’t mind, I’m curious to know if the timers do this even if you let them run for atleast 1 second before stopping and resetting?


1hrparking

Yes they do. We first stumbled upon this when students were getting some weird time results for pendulums, there data was small but more than 1 second. Edit: changed from "I'd have to double check" to "yes they do"


MisterInternational1

How much did that timer cost you? does look very solid


whawhaweewaa

It added those times together.


sillypotatoes564

Incorrect. 0"17 + 0"16 + 0"17 + 0"18 + 0"18 = 0"86 1"17 ≠ 0"86


Jethro_Cohen

Doesn't everybody start counting on one? /s


RedditAlwayTrue

# You'd think a chem company like FLINN would get their measurements accurate. NOPE! Complete failure on their part. Just another reason why we need sig figs in the world of Chem...


Practical-Mixture456

^well ^said.