DMM with headphone jack - Page 1
Forum section: electronics / testgear

author: bkw
author_rank: Contributor
timestamp: November 17, 2020, 12:07:40 am
content: Has anyone ever heard of a DMM with a headphone jack so that I can use the continuity beeper without filling the (shared) airspace with my constant beeps?

author: IanB
author_rank: Super Contributor
timestamp: November 17, 2020, 12:14:38 am
content: Quote from: bkw on November 17, 2020, 12:07:40 amIt's never going to happen.But one possibility is Bluetooth and wireless ear buds. Maybe a feature suggestion for a Bluetooth-enabled meter?Could also be an idea for noisy environments where there is machinery running.Also, can you not use the back light instead of the beeper?

author: Circlotron
author_rank: Super Contributor
timestamp: November 17, 2020, 12:30:10 am
content: Quote from: IanB on November 17, 2020, 12:14:38 amDepends on how little the meter manufacturer values the life of the user...I can just imagine shortcuts likely to be taken with the insulation / isolation between the main meter circuitry and the headphone circuitry that is practically touching each side of your head.

author: Fungus
author_rank: Super Contributor
timestamp: November 17, 2020, 02:21:51 am
content: Quote from: bkw on November 17, 2020, 12:07:40 am

author: ejeffrey
author_rank: Super Contributor
timestamp: November 17, 2020, 04:19:57 am
content: Maybe a bluetooth headset?Or you could add a headset jack to the fluke 233 detachable display module.It seems like a pretty niche application.

author: Fungus
author_rank: Super Contributor
timestamp: November 17, 2020, 05:40:32 am
content: Open the meter up and put a resistor in the beeper wire?

author: bkw
author_rank: Contributor
timestamp: November 17, 2020, 06:04:28 am
content: I was actually thinking about the bluetooth possibility. One meter I'm using at the moment is an OWON BT35T, and I can read that from a shell prompt in linux. If I can do that, than it's only a couple steps to lash up some Rube Goldberg script to play a beep in the laptop headphone jackProbably with a maddening delay.I'll probably hack in a jack. Especially on a cheap meter.The backlight is not much good as a beeper since I'm looking at the probe tips not the meter. TSOP legs and other tiny features need magnification and my full attention. I mean, why else do meters HAVE beepers if not because not all problems are served by having to look at the screen? The closest thing to a useful use of that idea is someow rig up the screen to shine onto the area I'm poking at... be real.

author: Fungus
author_rank: Super Contributor
timestamp: November 17, 2020, 06:24:11 am
content: Quote from: bkw on November 17, 2020, 06:04:28 amMuch easier to hack in a decent light that shines on the work area, or even a light that attaches to the probe (something I always wanted). Maybe get a cheap meter and attach an Arduino to the beeper wires inside it to turn beeps into flashes.

author: alm
author_rank: Super Contributor
timestamp: November 17, 2020, 12:01:34 pm
content: Quote from: bkw on November 17, 2020, 06:04:28 amI would strongly recommend against this. If you connect any of the leads to a dangerous voltage like mains, intentionally or accidentally, the headphones will be at the same potential. And across your ears will probably be one of the worst places to get shocked. That's why people are recommending Bluetooth, to provide isolation between the meter and your headphones. The isolation in a handheld meter is usually provided by the plastic case.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 17, 2020, 04:54:45 pm
content: Yes, this is the important point. In a handheld DMM the entire circuit floats at the voltage of the common / - terminal including the microprocessor, display, and any IO. There is no isolation like you would find in a bench instrument.This is why logging meters typically use an optical output that shines through a clear window in the case, or in the case of newer devices wireless communication like bluetooth.Adding an electrical interface like a headphone jack seriously compromises the safety and renders any rating it may have invalid. Not only does it provide a shock hazard when using higher voltages, if you (or someone else) connects the headphone jack up to a line input on a computer, you would be connecting the common terminal of the meter to the computer ground which can allow destructive currents to flow even at low voltage.

author: ResistorRob
author_rank: Regular Contributor
timestamp: November 19, 2020, 06:40:53 am
content: My uncle added a headphone jack to his meter. He was measuring the voltage on a utility pole.His head was glowing like a lantern when I found him.He might have added Bluetooth to his meter also because it sounded like Lady Gaga squealing until the firefighters pried him loose.

author: bkw
author_rank: Contributor
timestamp: November 19, 2020, 07:43:15 am
content: Quote from: Fungus on November 17, 2020, 06:24:11 amNow THAT is an idea!

author: 2N3055
author_rank: Super Contributor
timestamp: November 19, 2020, 01:04:29 pm
content: You could add optical SFPDIF (toslink)port and use that ....Or just use TOSLINK TX/RX to send signal on/off.

author: Circlotron
author_rank: Super Contributor
timestamp: November 19, 2020, 09:44:11 pm
content: Quote from: 2N3055 on November 19, 2020, 01:04:29 pmOr have the toslink cable taped to one of the probes so that it shines next to where the tip of the probe is contacting. Flash for extra visibility.

author: tom66
author_rank: Super Contributor
timestamp: November 19, 2020, 09:48:25 pm
content: Years ago I had a cheap multimeter that flashed the LCD backlight on continuity testing.It also beeped but you could presumably remove the beeper.Sadly I've long since lost it and I don't know where you'd buy a similar one. It was from somewhere like Maplin (UK) or the likes.

author: 2N3055
author_rank: Super Contributor
timestamp: November 19, 2020, 10:01:14 pm
content: Quote from: tom66 on November 19, 2020, 09:48:25 pmNew Brymen 78x series does that...

author: Muttley Snickers
author_rank: Unknown
timestamp: November 19, 2020, 10:22:12 pm
content: Back in my day just about everything had a headphone jack, but nowadays it's a silly USB port. Universal my arse.

author: tautech
author_rank: Super Contributor
timestamp: November 19, 2020, 10:53:20 pm
content: Quote from: tom66 on November 19, 2020, 09:48:25 pmDaves BM235.Moderator Simon has them in his shop:https://simonselectronics.co.uk/product/eevblog-brymen-bm235-true-rms/Defpom's latest video has him using the continuity tester:

author: Fungus
author_rank: Super Contributor
timestamp: November 20, 2020, 03:51:12 am
content: Quote from: tom66 on November 19, 2020, 09:48:25 pmSure, there's meters that do that, but the meter is hardly ever in the field of view. If the light was on the probe itself it would be 1000x better.