Is it just me, or is an hour meter of this capacity just not practical? - Page 1
Forum section: electronics / general

author: XOIIO
author_rank: Super Contributor
timestamp: July 23, 2015, 08:13:40 am
content: So, found this in the box of random stuff I had picked up, it's an hour meter, 4.5-35v dc, and ticks up once every hour (although if you cut power to it, at least gradually, it ticks over so it can be fooled).The thing that's odd about it is the fact that it could count up to 1,140 years and 292 days (with a little bit extra)To me that just seems insane, I'm trying to think of an actual, practical use this thing would have to count up that high, the only things that I can think of are either some sort of time capsule, or maybe back when they were making nuclear bunkers, hooked up to a computer system. I'm quite curious as to what sort of project would involve such foresight that they would need to be able to count up this long. I'd love to hear about some practical uses.It also seemed impractical to me as they would have to spend money on all the extra parts, while extremely minimal, to count up all those digits, then part of me thought that perhaps there is a version available in minutes, all they would need to do is change programming on the chip (or a resistor) to change it to that, in which case it would only count up 19 years or so.But yes, I'd love to see some real world examples where they took that much time into account when designing the project. It makes me want to make a time capsule of some sort but that would require one heck of a good spot to put it in to last that long. (and have power)

author: Deathwish
author_rank: Unknown
timestamp: July 23, 2015, 08:20:04 am
content: space travel ?

author: XOIIO
author_rank: Super Contributor
timestamp: July 23, 2015, 08:24:27 am
content: Quote from: Deathwish on July 23, 2015, 08:20:04 amAh, you know that would be a good one, we haven't gotten there yet but for any sort of system using hibernation this would actually be practical. Much lower power than a display (led or lcd, although I'm thinking E-paper might be lower yet), so it would be more efficient (uses 85mw).Edit: also if you had some probe going near an event horizon of a black hole, if it was able to return, you could use this to see the effect it had on time.Part of me wonders if the mechanisms inside can even last that long, I guess they must have had to do some accelerated testing to see if they did.

author: coppice
author_rank: Super Contributor
timestamp: July 23, 2015, 08:55:13 am
content: I've never driven a car which could get the speedo anywhere close to the end of the scale, but that doesn't stop them being built that way for inspirational effect. :-)

author: dexters_lab
author_rank: Unknown
timestamp: July 23, 2015, 09:20:58 am
content: they might have almost identical models of that meter that work in minutes or seconds?

author: ruffy91
author_rank: Regular Contributor
timestamp: July 23, 2015, 09:32:49 am
content: The red digits are 1/10th and 1/100th hour, so the counter goes to 99'999.99 Hours, about 11 years like most hour counters. (There are hour counters that have 8 hour digits so about 110 years.)Look at the eaton catalog (http://www.eaton.com/Eaton/ProductsServices/Electrical/ProductsandServices/PowerQualityandMonitoring/index.htm) for example on page 105 and 106.

author: XOIIO
author_rank: Super Contributor
timestamp: July 23, 2015, 09:45:54 am
content: Quote from: ruffy91 on July 23, 2015, 09:32:49 amAh, ok that would explain the different color, the datasheet I found didn't show that information. That definitely makes it a bit more practical.

author: XOIIO
author_rank: Super Contributor
timestamp: July 23, 2015, 04:11:00 pm
content: Hmm, I have a fairly thick steel enclosure, it has very specific mounting for a +/-15v power supply in it, really nicely done, but if I put in a much smaller supply, took ages to make a cutout for this, and had a generous amount of capacitors in it, in theory I could make something that would stay plugged into the mains and count up, and have enough reserve capacity to survive power outages and moving, so that I could have this thing set up with power for the next 19 years.God, that's a long term thing to set up lol, I'd probably get tempted to re-use the enclosure at some point or something, but it would definitely be some sort of accomplishment. Really I should stick an attiny with a buzzer to go off in 19 years too, I have an RTC for arduino somewhere but the battery wouldn't last, so this would purely be a silver box with a power cord and the counter on it.It would definitely be a conversation piece, I'm pretty tempted now. Maybe I should use some 1 farad supercaps off ebay though, instead of a bunch of larger (physically, but not by capacity) ones.Hardest part would be cutting a nice hole into the enclosure. I wonder if the charger from a bluetooth headset could run for 19 years non stop too. HmmI just need to find a way to reset this thing, I would either have to crack it open, which would likely damage it, but I'm thinking an arduino script to toggle power a buttload of times would work too. It would just take a bit longer.edit: Hmm, cracking it open it is, it's not just a cut of power that does it but the slow decline as the caps in the supply lose charge.edit 2: ah good it slipped out pretty easily, just needed the right angle.

author: SeanB
author_rank: Super Contributor
timestamp: July 23, 2015, 04:59:13 pm
content: Hour meter on the compressor did 47000 hours before it carked a gear and stopped running, though admittedly it was a used one, pulled out from a sewage pumping plant, where it had run on a big Grindex pump for a couple of decades before I got it. I had around 200 hours of running on it, as the motor in the compressor is running at a very low duty cycle of around 2 hours a month. Seriously oversized, but better than a tint little rattler that would die in 2 years like the first one, when I bought this massive Ingersoll Rand 100CFM unit with 300l tank second hand. This one will only die when the tank fails it's 5 year pressure test, when I likely will transfer the parts to a new tank. Already had to replace the compressor head when it dropped a HP piston and punched it to pieces, and a new side was more expensive than a complete new unit. Came from previous owner not changing oil, I now run synthetic oil in it only.

author: Red Squirrel
author_rank: Super Contributor
timestamp: July 23, 2015, 05:32:22 pm
content: Telecom air dryers maybe? Some of those have been running for decades non stop other than servicing. I guess it does not cost a lot to add a couple extra digits so it gives you assurance that it has not rolled over when it has a 1k+ year capacity.

author: Rick Law
author_rank: Super Contributor
timestamp: July 23, 2015, 06:24:40 pm
content: Quote from: XOIIO on July 23, 2015, 08:13:40 amRadioactive, Chemical and Biological waste handling are possibilities.If the radioactive waste half-life is 100 years. 1000 year (10x half-life) would not make it safe yet. So this would be for fairly short half-life stuff.Whether it is for radioactive waste or not, question is how they would power it for that long. The storage limestone cave may be power now, but who knows in 50,000 years.

author: SeanB
author_rank: Super Contributor
timestamp: July 23, 2015, 06:51:49 pm
content: Just remember that the same counter mech is also used for totalising counters, where you can count to the appropriate count of 9999999 in a realistic time.I have a machine counter that counts 999999 and then rolls over. It is sitting at present on over 2 million cycles. having rolled over twice since I installed it around 5 years ago. Before I got it it was a page counter in an old AM International industrial copier I got as scrap from the agents, as I wanted the mains transformer ( 15kg that I will one day make into a spot welder) and they said "take the whole thing, saves us dumping it".Not sure how many copies that made, they generally were scrapped at around the 100 million copy mark in heavy use, or 20 years. Those old units could do that, as they were made from steel plates, with proper ball races on every pivot, and all parts were available as spares that could be installed in under 2 hours for the most part.