What is this short beep in DMM continuity test called? (NorthridgeFix) - Page 1
Forum section: electronics / testgear

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 06, 2021, 01:06:26 pm
content: So this guy NorthridgeFix on the internet shows repairs.When he test diodes or caps, his DMM (or expensive bench meter, who knows) gives a long beep when continuity is detected. As usualBut also it gives a short beep when it senses a good probe connection is made, but no continuity exists.I suppose it somehow senses this with some capacity change on the probe, or change in noise level or something.Link to video on the correct time:https://youtu.be/k1yqToaIUII?t=302Edit: some confusion due to the video, please note this beep is not just a diode test.It also beeps for good measure connections to capacitors, seethis segment of the video.This is very useful.To separate non-continuity versus dirt or oxide layers.But non of my meters have this, and I never seen it (or noticed it) until I watched this guys video'sThanksWhat is this function called? What to pay attention to in DMM specs? Which brands have this?Thanks

author: 2N3055
author_rank: Super Contributor
timestamp: January 06, 2021, 03:25:06 pm
content: Most Fluke handhelds have that type of continuity/diode test.New Brymen series 785/6/8 (Including Dave's BM786) have it too...

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 06, 2021, 08:12:20 pm
content: ThanksI was sort of fearing that (pricewise)I do have one Fluke, but it's an ancient one, given to me by an old guy when I was young. Which was long ago.Does this feature have a specific name/phrase attached to it?

author: 2N3055
author_rank: Super Contributor
timestamp: January 06, 2021, 08:53:48 pm
content: Fluke doesn't call it anything special.Brymen cals it's implementation BipLit Diode test.My old Fluke 73 III has it.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: January 06, 2021, 09:46:59 pm
content: My cheap-o Habotest Ht108L has it too. It will beep on a non shorted diode and give the voltage drop.It cost less that 8.50USD.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 07, 2021, 12:52:34 pm
content: @JN: Is that the same though?Yes it is common to beep on diode in forward direction with showing voltage drop.They all have that.But here, it gives a short beep when the probe makes good electrical connection, even on a reverse diode, or capacitor. Or any open circuit connection.Maybe my example video should have started one minute lateron this segment of the video.And a normal beep when it is a forward diode or continuity.I suspect that is what your Habotest Ht108L has, but it is not quite the same.---Edit: Although, there is one thing that your meter has different then other cheapo and mid-range DMM:It has 2 separate settings for Diode and Continuity (diode and sound symbol)All 3 of my meters, and all pictures I found on internet, has a single joined setting. Your Habotest Ht108L has reserved two settings on the selector switch, which seems like an important cost to make on such a "el-cheapo" item.So please elaborate, confirm, or even make a video?More edit: This meterdoes indeed have something special.But maybe not on capacitors. Could you check please.----@n3055 : I cannot find any ref to "BipLit" not even in the manual.

author: 2N3055
author_rank: Super Contributor
timestamp: January 07, 2021, 01:20:48 pm
content: Quote from: cybermaus on January 07, 2021, 12:52:34 pmNo, it doesn't work like that.If probes are open it is quiet and shows OVL on screen. It will show this too if you connect it to diode in reverse. You will get NO reaction.When you forward connect diode, it will beep once short and show forward voltage drop of diode. (it reacts to certain range of forward voltage cca from 0,1-0,15 to 0,7V)If it detects connection and voltage is too low (short) it will beep all the time you are connected..

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: January 07, 2021, 01:28:10 pm
content: 2n3055 is correct. It does seem to have a special function just for testing diodes. It will light up a red led but the voltage is not good enough to light up a blue one.Anyway it is so cheap that feature itself makes it unique.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 07, 2021, 01:48:48 pm
content: Ah, you edited at the same time as me.Yes, it does make it unique.But really check outthis segment of the videoa minute later.Watch for a full minute or so.So does the Brymen of Fluke do that?

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 07, 2021, 02:01:57 pm
content: Ah fuck it.This diode featureand thiscontinuity performancecombined, as well as thehigher LED test voltage, I'll order one. I think I can carry the cost without going under.

author: 2N3055
author_rank: Super Contributor
timestamp: January 07, 2021, 02:10:44 pm
content: Quote from: cybermaus on January 07, 2021, 01:48:48 pmYou seem to not understand how it works..That guy is using Fluke meter, by the sound of it.And it works exactly how I said.He's testing in circuit, with many components connected together.There are diodes, resistors, capacitors, transistors, input protection diodes in integrated circuits....You cannot check for "good circuit". You can detect dead short, or nothing, and then some voltage drop in between.Charging/discharging capacitors will also create false diode beep.That is why I don't really rely on this short beep business at all. I test in continuity mode, and watch at voltage...

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 07, 2021, 02:27:04 pm
content: You are probably correct.I realise there is always some in-circuit weirdness going on. Near impossible to check actual values in-circuit. Even with special in-circuit ESR meters, it rarely works.And it is quite possible those capacitor beeps come from other components and diodes.What I though I was seeing was a advanced meter that noticed, by stray capacitance chance, or stray noise change, or maybe even transmission line reflection change, that the probe had made contact. Even if contact to an open trace or high impedance circuit.But if you say you even recognise the fluke beep, then alas, it is indeed merely this simple diode beep.Still, if that el-cheapo has the same, I'll experiment with it.