About VTVM today - Page 1
Forum section: electronics / testgear

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 04:32:12 am
content: Using VTVM is really useful now, or just nostalgia thing? There is something in it that does not make a good (With bargraph)DMM?

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 04:33:48 am
content: I need an opinion on a good brand DMM with Bargraph

author: VK5RC
author_rank: Unknown
timestamp: June 10, 2014, 05:15:14 am
content: Quite a few good dmm have bar graph on the bottom of the display, some guys really like an analogue meter for 'peaking' manually a circuit, I think it may be a bit of overkill :-) Fluke 87, Agilent U1253b have the bargraph

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 05:30:06 am
content: I think the bargraph has a behavior like a needle (I can be wrong) But, what do you think about that?

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 05:36:09 am
content: Someone knows this brand of dmm? seems good for a regular use:http://www.ebay.com/itm/PeakTech-2015-Multimeter-3-3-4-stellig-20-A-AC-DC-mit-Bargraph-CAT-III-CAT-IV-/360845358264?pt=Mess_Pr%C3%BCftechnik&hash=item54040f34b8

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 10, 2014, 06:13:51 am
content: Quote from: SAUL BRITTO on June 10, 2014, 05:30:06 amWell, yes and no. No bar-graph has as much "resolution" as an inexpensive analog meter. Resolution is the ability to tell the difference between two adjacent values. A DMM with a bar-graph can give you moderately-fine resolution (depending on how many segments it has). But it can not show you the fine detail for critical peaking, etc. Of course, once you are that close, you could just watch the least significant digit go up or down.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 03:37:09 pm
content: Quote from: Richard Crowley on June 10, 2014, 06:13:51 amI think the precision and velocity of an AD converter array, will be very important too when you measure AC or a floating (Defective) DC.

author: N2IXK
author_rank: Frequent Contributor
timestamp: June 11, 2014, 01:46:20 am
content: I work on a lot of vintage gear, but I really don't find myself turning on my VTVM very often. The major advantage of a VTVM was the high input impedance, which you get with even the cheapest DMM nowadays. And a bargraph display simulates a moving needle well enough for peaking and nulling tuned circuits, etc.What I do find myself using occasionally on older gear is a good old fashioned VOM. Many of the voltage reading specified on schematics for old gear were taken using either a 1K or 20K ohm per volt VOM. Using either a VTVM or modern DMM can result in higher than normal readings because they don't load the circuit in the same way as a VOM does. One bit of gear (old tube tester) I was working on recently simply couldn't be calibrated properly using a my Fluke 87 meter unless I added a resistor across the input to simulate an old VOM on a 150V range.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 11, 2014, 02:11:35 am
content: Many of the voltage reading specified on schematics for old gear were taken using either a 1K or 20K ohm per volt VOM. Using either a VTVM or modern DMM can result in higher than normal readings because they don't load the circuit in the same way as a VOM does.Yes it's pure true! You touched on a very interesting aspect of the meters, I bet a lot of people never realized this truth, especially me! Thank you man.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 11, 2014, 02:18:55 am
content: Then, respecting other opinions of course, believe VTVM is just a matter of liking (I like). Guess is very elegant use a VTVM hehehe!

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 11, 2014, 04:52:20 am
content: Using a VTVM means that you have an additional project. You must find and refurbish and calibrate your VTVM before you can use it. Of course you will need to get a modern DMM to help get the VTVM operational.

author: linux-works
author_rank: Super Contributor
timestamp: June 11, 2014, 02:24:13 pm
content: see my post on the triplett handheld 'mighty mite' meter I bought last weekend.I found quite a few on ebay, and many for reasonable amount of money. they can be found for $20 or less, sometimes with nice leather cases, too.its not high input z but it is a very nice meter movement, its small and portable and its a triplett, which does mean something (50+ yr old brand).I also like my simpson 260 VOM. bigger but definitely a classic.don't waste your time on vtvm. they offer NOTHING today that is useful. get a VOM or fet-vom. bargraphs on lcd's are not so great as it may appear.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 11, 2014, 07:57:10 pm
content: Quote from: linux-works on June 11, 2014, 02:24:13 pmTHEN WE CAN SURVIVE WITHOUT A VTVM!

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 12, 2014, 01:37:58 am
content: Quote from: SAUL BRITTO on June 11, 2014, 07:57:10 pmNOBODY needs a VTVM.40 years ago it was a decent solution to a problem that was "state of the art".But even very modest DMMs of today are far superior to those old unstable things.They are museum pieces with no practical value in the 21st century.Unless you have some sort of fetish for firebottles and waving needles.

author: linux-works
author_rank: Super Contributor
timestamp: June 12, 2014, 02:41:01 am
content: zero the left. then zero the right. then zero the left again.that's crazyoh wait, it just warmed up a bit more. we have to re-zero it.yeah, no reason to use a vtvm anymore. that used to be the best high-z meter technology but then the fet-vom replaced that, and now dmm's replace them.I still love a good meter movement and I value that for some applications, but you can get meter movements without tubes, now

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 12, 2014, 04:14:20 am
content: May have the advantage of being more tolerant of certain human errors !DMM= Do not make a mistake or... BUM! hahaha.And no more than that.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 12, 2014, 04:43:20 am
content: Linux-Works,what is the input impedance of a simpson 260? Found one on ebay for 55,00 US.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 12, 2014, 05:03:43 am
content: After our conversation, think that an old flawed knight, will mutate into a esr meter

author: linux-works
author_rank: Super Contributor
timestamp: June 12, 2014, 06:04:33 am
content: input z is in 'ohms per volt'. which is not a constant.

author: N2IXK
author_rank: Frequent Contributor
timestamp: June 12, 2014, 10:42:10 am
content: The Simpson 260 is 20K ohms per volt.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 12, 2014, 10:34:34 pm
content: Quote from: N2IXK on June 12, 2014, 10:42:10 amThis in DC right?AC is like any regular meter,8k, 5k? If right,then one has a simpson basically like if you have a VTVM, only because is beautiful and likes.Today any cheap meter have a Z20k/V.Except for the issue of robustness, it seems to me a very strong equipment

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 12, 2014, 10:51:09 pm
content: Hey people do you have a Tektronix Dmm912 is it a good DMM?

author: N2IXK
author_rank: Frequent Contributor
timestamp: June 12, 2014, 11:47:09 pm
content: Yes, 20K per volt DC, 5 K per volt AC.Quote from: SAUL BRITTO on June 12, 2014, 10:34:34 pm

author: Nerull
author_rank: Frequent Contributor
timestamp: June 13, 2014, 02:50:59 am
content: Quote from: SAUL BRITTO on June 12, 2014, 04:14:20 amWhat DMMs are easily damaged by mistakes?Aside from trying to measure voltage with probes in the current sockets, which will cause problems with any equipment analog or digital, they're almost impossible to accidentally damage. See Dave's shootout where he tested even cheaper meters by doing things like putting mains voltage into the ohms mode.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:06:41 am
content: Mistakes do not match "the correct sockets", mistakes are mistakes!Nothing is indestructible.I had said that perhaps "maybe" a circuit of a VTVM could be less sensitive to errors.

author: c4757p
author_rank: Super Contributor
timestamp: June 13, 2014, 03:08:05 am
content: Quote from: SAUL BRITTO on June 12, 2014, 04:14:20 amYes, as oppposed to analog voltmeters, which are pleased as Punch to measure 800 V on the 2 V range continuously.

author: Nerull
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:35:11 am
content: Many VTVMs had the common lead connected directly to the chassis and could electrocute you if you connected the probes the wrong way. How's that for a mistake?

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:48:16 am
content: As I said mistakes are mistakes. I'm not making a defense of VTVM just want opinions about the two worlds

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:52:48 am
content: This make me happy, to know that dmm's are so secure