DMM with NO auto OFF - Page 1
Forum section: electronics / testgear

author: Jwillis
author_rank: Super Contributor
timestamp: November 15, 2021, 04:08:00 am
content: Is there such a thing as a DMM aside from a bench meter that has a switchable auto off function ?I couldn't care less how many batteries it's supposed to save .One would figure in this day and age that a $100 to $200 hand held DMM would be rechargeable with an external power supply that disables the auto off when connected .It's really annoying when I have multiple multi meters trying to take measurements and I have to keep switching the darn things back on continuously. Or when I'm about to take a measurement in a place that's hard to get , the darn thing shuts off.Sorry I'm venting but really.

author: bdunham7
author_rank: Super Contributor
timestamp: November 15, 2021, 04:51:39 am
content: All of my Fluke handhelds have an option to disable auto-power-off except the 27, which doesn't have it in the first place. That includes a 116, 189, 289 and the 27.

author: HKJ
author_rank: Super Contributor
timestamp: November 15, 2021, 05:58:34 am
content: Quote from: Jwillis on November 15, 2021, 04:08:00 amIt is fairly common and usually activated by holding down a button while turning the meter on. Look for meters with a indicator for auto-off active on the display.

author: Berni
author_rank: Super Contributor
timestamp: November 15, 2021, 06:32:22 am
content: Most of the reason that handheld DMMs don't have external power adapters is for safety reasons to keep the meter floating. But i do once remember seeing a rechargeable DMM that can charge itself by sticking the probes into a mains outlet, pretty neat feature that i never seen since, tho it does feel a bit sketchy leaving a meter sitting around with probes dangling out of a wall socket.But as HKJ said. A lot of the more advanced DMMs with lots of buttons tend to also have a way to disable auto power off by holding a certain button at power on. Often the button is not labeled as such, so you need to read the manual to find out what button it is. But the meter will tend to have some sort of icon on the screen to indicate auto power off being active. I think on my Agilent handheld DMM the icon is just the text "APO"Also when working in the lab this is also a good reason for having one or two bench DMMs. They don't auto power off, they don't take up bench space, are more accurate and usually have some sort of self illuminated display that is easy to read at any angle in the dark.

author: Fungus
author_rank: Super Contributor
timestamp: November 15, 2021, 07:35:50 am
content: Quote from: Berni on November 15, 2021, 06:32:22 amHuh?

author: Berni
author_rank: Super Contributor
timestamp: November 15, 2021, 08:19:25 am
content: Quote from: Fungus on November 15, 2021, 07:35:50 amA bench DMM can stack on the shelf behind my bench. Goes on top of my PSU, other PSU, scope, electrometer, other DMM...etc So since it stacks on top of something and stuff can be stacked on top of it, the extra surface area used by it is 0. Can't do that with a handheld DMM.

author: Fungus
author_rank: Super Contributor
timestamp: November 15, 2021, 09:02:07 am
content: Quote from: Berni on November 15, 2021, 08:19:25 amBench meters definitely take up space by default.Quote from: Berni on November 15, 2021, 08:19:25 am

author: Synthtech
author_rank: Regular Contributor
timestamp: November 15, 2021, 09:36:00 am
content: My Hioki meter can disable Auto-power-off by holding a button during -power up. Unfortunately none of my Hioki or Keysight handheld DMMs allow for the auto backlight cutoff to be disabled and I absolutely hate having the backlight go off in the middle of taking readings.A backlight is there for a reason - to light the display in poor ambient lighting conditions. If I turn the backlight on I want it on for a reason and I don’t want it shutting off randomly - it’s a safety issue.

author: HKJ
author_rank: Super Contributor
timestamp: November 15, 2021, 09:45:56 am
content: Quote from: Synthtech on November 15, 2021, 09:36:00 amKeysight often has a configuration menu where you can adjust backlight timeout. Some Hioki can disable backlight timeout.

author: HighVoltage
author_rank: Super Contributor
timestamp: November 15, 2021, 09:46:49 am
content: The many Keysight handheld DMM also have this habit of turning off at the most inconvenient time. But if you use remote control to an iPad, they will not turn off automatically anymore.

author: Fungus
author_rank: Super Contributor
timestamp: November 15, 2021, 09:58:35 am
content: Quote from: Synthtech on November 15, 2021, 09:36:00 amYep. Shutting off automatically iscompletely stupid.Would they make auto-power-off flashlights?

author: dl6lr
author_rank: Frequent Contributor
timestamp: November 15, 2021, 12:22:56 pm
content: Quote from: bdunham7 on November 15, 2021, 04:51:39 amFluke 23 has no option to disable automatic shutdown AFAIK. At least the manual does not state it. It goes to sleep after 1h.

author: nctnico
author_rank: Super Contributor
timestamp: November 15, 2021, 01:21:26 pm
content: Quote from: Jwillis on November 15, 2021, 04:08:00 amBeen there done that and ended up buying bench DMMs. They don't have to cost much either. Vici VC8145 (4.5 digit) is right in your price bracket and you can stack them as well so they take less bench space compared to a handheld.

author: gslick
author_rank: Frequent Contributor
timestamp: November 15, 2021, 05:02:39 pm
content: Quote from: HKJ on November 15, 2021, 09:45:56 amThe Keysight U1281A/U1282A have a Setup menu where the automatic power-off timer can be set between 1 to 99 minutes, or disabled, and the automatic backlight timer can be set between 1 to 99 seconds, or disabled. The defaults are enabled at 15 minutes for the power-off timer, and enabled at 15 seconds for the backlight timer.Keysight U1281A/U1282A Handheld Digital Multimeter User’s GuideManual Part Number U1281-90003, Edition Edition 02, January 2021https://www.keysight.com/us/en/assets/9018-04069/user-manuals/9018-04069.pdfPage 123, Changing the Auto Power-Off and backlight timeoutsI have never bothered changing either timeout on my U1282A. I don't have any other Keysight handheld DMMs and haven't looked at any other Keysight handheld DMM manuals.

author: bdunham7
author_rank: Super Contributor
timestamp: November 15, 2021, 05:11:12 pm
content: Quote from: Fungus on November 15, 2021, 09:58:35 amMost handheld DMM users are probably more concerned about coming back to a meter with dead batteries after they forget to shut it off rather than having it shut off once per hour if you don't use it or move the switch. I haven't turned the feature off on any of mine that have it, although I increased the time. This is probably less of a concern for the 27--it is still using the original battery that came with it.

author: Gyro
author_rank: Super Contributor
timestamp: November 15, 2021, 05:57:33 pm
content: I'm not clear if you are "venting" about meters in the $100-$200 rangespecifically? The humble UT61E and follow-ons have no auto off (unless you modify them) because of the permanent data output function.

author: Fungus
author_rank: Super Contributor
timestamp: November 15, 2021, 05:58:17 pm
content: Quote from: bdunham7 on November 15, 2021, 05:11:12 pmThere's no reason it can't do both.eg. Many meters can disable the APO by holding down a button at startup. Why doesn't that disable the backlight timer, too?Quote from: bdunham7 on November 15, 2021, 05:11:12 pmMine, too.

author: myf
author_rank: Regular Contributor
timestamp: November 15, 2021, 06:10:30 pm
content: Hi everybody !The (now old) UT-61 disable auto-power-off when usb-link is on. Batteries last to a long time, more than 24h, maybe about 100h with 8.2V-200mAh-NiMh batteries. I'm sure what UT-61e has NO auto-power-off.Have a nice day.F. (in France)

author: floobydust
author_rank: Super Contributor
timestamp: November 15, 2021, 06:25:01 pm
content: I agree this feature is now beyond annoying, it's been overdone. Batteries must cost a year's wages in china, or they don't last at all, filled with air?It wails and beeps before shutoff as a warning, then it wails and beeps when it's done."APO" icon to the LCD is where this seems to have climaxed, what a stupid idea and wasteI'll never buy a multimeter having that stupid annunciator.It's also annoying the backlight timer is just as in your way. 15 seconds? 99 seconds? Then fumble around in the dark to turn it back on. That pisses me off.A decent powersave timer should retrigger on any button press or rotary switch twirl, or maybe non-static readings, if activity is present- restart the timer.With the single-chip DMM's, e.g. Dreamtech chipset stores auto power off and backlight timer period in EEPROM. So it's a hassle to change. The one-time disable power down timer is still too much hassle, 6 beeps.Power off timeout set in 1 minute increments 1-255, default 15 minutes. 0xFB=0x0FBacklight timeout set in 1 second increments 1-255, default 15 seconds. 0xFC=0x0F

author: Fungus
author_rank: Super Contributor
timestamp: November 15, 2021, 06:36:22 pm
content: MY BM857 has "intelligent" APO. It doesn't switch off if you're taking readings and numbers are changing on screen, you don't even have to touch the dial.It doesn't apply to the backlight though.

author: BeBuLamar
author_rank: Super Contributor
timestamp: November 15, 2021, 07:08:44 pm
content: DMM batteries can last for a few hundreds hours and when the low battery indicator is on it can still be used for sometimes. The DMM is not used daily and the rechargeable batteries tend to go dead just when you want to use it. So no I don't want a DMM with rechargeable batteries.

author: Shock
author_rank: Super Contributor
timestamp: November 15, 2021, 07:53:01 pm
content: Fluke 87V does as well.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 15, 2021, 08:54:30 pm
content: Quote from: Fungus on November 15, 2021, 09:58:35 amAll the stuff powers off automatically when the batteries are depletedAnything else is considered failure.

author: mariush
author_rank: Super Contributor
timestamp: November 15, 2021, 09:07:35 pm
content: Someone already mentioned, but saying it ... ut61e from uni-t doesn't have auto power off because serial output is enabled alwaysA lot of meter chips have some data logging features that may not always be exposed ... but you could use a resistor to pull up/down that pin and enable serial output on that chip and disable auto power offYou could probably also hack a lot of multimeters by adding a tiny circuit to periodically press a button or something... for example press on backlight enable to reset the timer, or to press on same function already selected (ex press DC voltage when already on DC voltage)

author: DRL
author_rank: Newbie
timestamp: November 16, 2021, 02:52:11 am
content: The craziest one I had was a Radio Shack handheld with a data logging function that turned off after 20 minutes if you left it alone … no published way to disable the “feature”. All it took was one time of collecting some oven temperature data over 4 hours (and running back in every 19 minutes to press a button on the meter) to throw that thing in a drawer forever.

author: Jwillis
author_rank: Super Contributor
timestamp: November 16, 2021, 03:24:13 am
content: Thank you everyone for the responses and ideas . Trying to monitor several voltages and amperage's at the same time I just got so frustrated last night trying to make some fine adjustments and experimental circuit changes to a project I'm working on .Really appreciate the help Thank You

author: Axtman
author_rank: Regular Contributor
timestamp: November 16, 2021, 05:45:20 am
content: Auto power off is a great feature. You don't know how many times I gone to the shop only to find that I accidentally left my Fluke 87 meter on. It has saved me a bucket full of 9 volt batteries. I think my Fluke meter turns off after 1/2 hour of no use.

author: Berni
author_rank: Super Contributor
timestamp: November 16, 2021, 05:58:29 am
content: Quote from: Axtman on November 16, 2021, 05:45:20 amYeah this is the reason i like having auto power off. It only takes once to forget to turn off a DMM in order to destroy the battery,I roughly know the button to hold when powering up my meters to turn off auto power off for when i really do need the meter to stay on. Also there is no way to 'turn off the backlight' on my OLED display meter (that on those AAs still gets the same battery life as a lot of LCD meters ).

author: PushUp
author_rank: Regular Contributor
timestamp: November 16, 2021, 05:34:49 pm
content: As far as my Agilent U1272A is concerned - there is no problem:APo = offblit = off...no problem at all to stay on with backlight on till the end of battery life:The same applies to the U1233A and the U1273A without the need of having "blit off", because of OLED!As far as my Fluke 113, 117, 179, 87V is concerned: in "MinMax" mode they also do not power off. Therefore you can use the "power up option" "Loff" and you have "nearly" the same...Cheers!

author: Greg J
author_rank: Regular Contributor
timestamp: November 27, 2021, 09:50:36 am
content: On my "cheap" Vici VC97, I found an answer!Just turn the meter on with the DC/AC button depressed. I tried all buttons, and this one seems to work fine. It's sat there all night measuring and battery is still ok. Imagine that..

author: Shock
author_rank: Super Contributor
timestamp: November 27, 2021, 12:49:02 pm
content: Congrats, it's also written in the Vici VC97 manual.