Multi-meter to measure short 100ms burst voltage?  - Page 1
Forum section: electronics / projects

author: Konga
author_rank: Newbie
timestamp: February 08, 2018, 03:19:55 pm
content: Hello,First post on the forum and i am by no means an electronics expert so please go easyI am trying to measure the maximum short term voltage output of a class d amplifier whilst driving a dummy load (heater elements), i can measure a continual sine wave with a multi-meter no problem, but it is not fast enough to track a short 100ms burst...Does a multi meter exist that reacts fast enough to give a fairly accurate reading for short burst signals? Or will i need a scope?Ideally i would like to measure a 100ms sine wave and 1KHz and 50Hz.Thanks in advance.

author: paulca
author_rank: Super Contributor
timestamp: February 08, 2018, 03:37:51 pm
content: Even a cheap scope will measure a micro-second burst voltage. A good scope will measure a nano-second burst.The two key metrics are analogue bandwidth and (assuming digital scope) sample rate. Cheap scopes will be around 20Mhz bandwidth with 1mega samples per second. Expensive scopes go up to 100Mhz+ and 1-10giga samples per second.

author: Konga
author_rank: Newbie
timestamp: February 08, 2018, 06:48:21 pm
content: Thanks PaulcaI do have a scope but the amplifier is bridged so i beleave i need a differential probe to measure the output... I can measure un bridged class a/b amplifiers with the scope fine...

author: HKJ
author_rank: Super Contributor
timestamp: February 08, 2018, 07:24:28 pm
content: Any multimeter with a "Peak" function can measure a 100ms peak, but it will show peak voltage, not rms.A "min/max" usual is in the 100 to 500ms range and can show rms, a peak function is around 1ms and can only show peak values.

author: Konga
author_rank: Newbie
timestamp: February 09, 2018, 10:02:44 am
content: Thanks HKJMeasuring peak voltage at the crest of the wave seems like it should work, i can just multiply by 0.707 for RMS value. A 1ms window would be ok for a 50Hz measurement, but would be a full cycle for 1KHz, so im assuming it wouldn't work and it would read an average over the 1ms? some 50Hz measurements would be useful though.Would you be able to recommend a good budget multimeter with a peak function?Thanks again

author: HKJ
author_rank: Super Contributor
timestamp: February 09, 2018, 10:19:22 am
content: Quote from: Konga on February 09, 2018, 10:02:44 amI have not played with "higher" AC frequencies and peak functions, when testing them I use square pulses.Quote from: Konga on February 09, 2018, 10:02:44 amYou can always check my list of reviewed meters:http://www.lygte-info.dk/info/DMMReviews.htmlHold the mouse over the multimeter name to get a table with supported functions.It looks like the only review I have published for a meter with peak function is the Zeast 282 (It is a budget meter), but the bandwidth is a bit low for audio work.http://lygte-info.dk/review/DMMZeast282%20UK.html

author: Terry01
author_rank: Frequent Contributor
timestamp: February 09, 2018, 10:33:19 am
content: I remember one of Joe Smiths videos was about testing how quick meters were and how fast they actually gave 100% reliable readings. I don't remember exactly what tests he did but I do remember he was impressed with the Brymen 869s. I have the 867s and am very happy with it although I don't push it's boundaries.Maybe worth shooting Joe a mail? He will be able to tell you exactly what was what in his tests.Good luck and hope you find what your needing for your tests...

author: Konga
author_rank: Newbie
timestamp: February 09, 2018, 11:12:45 am
content: Thanks guys,It looks like the UNI-T UT61E is also an option, i will watch Joe Smiths videos and have a good look around and see what other options there are.Thanks again

author: alanb
author_rank: Frequent Contributor
timestamp: February 09, 2018, 01:46:40 pm
content: Quote from: Konga on February 08, 2018, 06:48:21 pmIf you have a dual channel scope you can combine the channels using A-B mode and then use the two probes in place of a differential probe.