KKmoon KKM828: opinions? - Page 1
Forum section: electronics / testgear

author: DiTBho
author_rank: Super Contributor
timestamp: April 14, 2021, 04:38:39 pm
content: The KKmoon KKM828 is a 2Mhz "visual" multimeter. I am tempted to buy one just to have something cheap on hands to check if the code of my MPUs are starting to move, plus a couple of measures about the batteries.

author: ledtester
author_rank: Super Contributor
timestamp: April 14, 2021, 05:13:28 pm
content: Be careful of the "2MHz" specification... it's listed as 2 mega samples per second but the bandwidth is stated here as 1 MHz:https://www.aliexpress.com/item/4001249211470.htmlbut I doubt the bandwidth is even that -- it's probably more like 200 KHz.If you just want to see if your digital I/O lines are twitching you can build a logic probe, e.g.:https://learn.adafruit.com/some-digital-tools/logic-probe

author: ledtester
author_rank: Super Contributor
timestamp: April 14, 2021, 05:18:39 pm
content: The KKMoon unit looks the same as the one reviewed here:

author: DiTBho
author_rank: Super Contributor
timestamp: April 14, 2021, 06:14:00 pm
content: Quote from: ledtester on April 14, 2021, 05:13:28 pmI need to measure the duty cycle of I couple of PWM operating at 100Khz, some voltages here and there, if possible I would like to avoid to carry on a multimeter only for this, and I have a couple of low DAC units operating at 200Hz.That's what I need for my simple tasks in automotive.Umm, a colleague has just told me about her latest purchase: it's a funny DSO-shell that is found with three band-labels on AmazonKumanArceliKmoon (it looks "kkmon" but with only one "k"?!?)Who is the original company who designed it? Who knows ... anyway, according to what she told me, she bought Arceli which looks quite a nice little bugger and its analog bandwidth looks to be down just 1 dB @ 5 MHz.It's declared 20 Msps sample at 5 MHz, she said the the sine wave still looked like a sine wave at 5Mhz, so probably the actual bandwidth is something close to 5Mhz. She concluded the phone telling her new little toy is still much better than anything in its price range.It's a very low cost DSO-shall powered by a little litium batter, it's not a combined DMM + DSO, and it looks very nice. I am tempted to buy one. It's priced between 50 and 65 Euro on Amazon.Mumble ...

author: tunk
author_rank: Super Contributor
timestamp: April 14, 2021, 07:56:38 pm
content: I think they're made by Fnirsi:http://www.fnirsi.cn/Here's a review:https://translate.google.com/translate?hl=en&sl=ru&u=https://mysku.ru/blog/aliexpress/72062.html&prev=searchAnd if you spend a bit more:https://translate.google.com/translate?hl=en&sl=ru&u=https://mysku.ru/blog/aliexpress/77475.html&prev=search&pto=aue

author: DiTBho
author_rank: Super Contributor
timestamp: April 14, 2021, 09:34:05 pm
content: Quote from: tunk on April 14, 2021, 07:56:38 pmwow, it looksthis. Unbelievable!!! Three companies cloning the same product

author: gby
author_rank: Frequent Contributor
timestamp: June 12, 2022, 04:05:43 pm
content: More out of curiosity than anything else I grabbed one of these KKM828 graphical meters.I have found this exact same device branded 4 different ways:KK Moon KKM828BangGood MT8208Unbranded ET828Liumy LM2020The price is all over the place. If you shop you should be able to get one in the US for $50 to $60 delivered.For comparison, from the same designers/factory there isMT8206 20 KHz BW, 200 ksample/sec240x160 monochrom LCD2000 count not TRMS, no Temp DMMSee HKJ's review athttps://lygte-info.dk/review/DMMMustool%20MT8206%20UK.htmlMT8208 1 MHz BW, 2.5 Msample/sec320x240 color display4000 count not TRMS, no Temp DMMMDS8207 40 MHz BW, 200 Msample/sec240x160 Monochrome LCD6000 count TRMS with Temp DMMSee HKJ's reveiw athttps://lygte-info.dk/review/DMMMustool%20MDS8207%20UK.htmlThere are many hand held "real" oscilloscopes in the $100 and up category that would put the KKM828 to shame for oscilloscope functionality. Most importantly, any "real" oscilloscope should have at least two channels to be able to do debugging with. Any single channel scope will be inherently a limited use case item. Looking at any signal with a meter's unshielded leads compared to an oscilloscope probe is asking for trouble above 10 MHz and maybe even between 1 and 10 MHz.What really impressed me about the 8208:- The oscilloscope function is actually reasonable. Yes limited but for what it is reasonable.- The oscilloscope function works for the current measurement mode!!The higher BW 8207 has a dedicated input terminal for the oscilloscope function and presumably only works for voltage mode. "Real" hand held oscilloscopes also would only measure voltage.In conclusion, I was less impressed with the DMM part than I expected and more impressed by the scope part than expected. As an additional tool I think this "graphical meter" can justify itself via quick portability to check for existence of signals or for signal tracing. As a starter oscilloscope or "real" oscilloscope replacement it would be a poor choice.Pros:Oscilloscope function works on the current ranges!!! 30 mA/div is very clean/noise free.Pretty good color display (twice resolution of other ones)Controls are reasonableTrigger works surprisingly wellCons:Fairly poor battery life for a hand held DMM...probably 65 HourNot TRMSI couldn't figure out how to make scope ac coupling. Always dc coupledmA current range is only 250 kHz BW while voltage is over 750 kHz10A current range is probably lower BW also but didn't readily have 1+ ampere test signal handyFastest sweep is only 2.5 uSec/div. Quoted 1 MHz BW implies 0.35 uSec step rise timeQuirks:Must enter scope from V/I ac and not dc.- Scope is dc coupled even started from ac modeIf you enter from V/I dc step response is way under calibrated....unusably soYou can enter oscilloscope mode from mV range for 30 mv/div. But, step response is waaaay under calibrated.- There is no mV ac mode to start in. Only dc.F4 held at turn on can turn beeps off...but setting is not rememberedTo measure higher capacitances must switch leads to two middle meter terminalsFYI:Works fairly well with 3 rechargeable NiMH batteries. Fresh battery shows half full symbol.IMHO:For this category best would be use meter leads and have 5-10 MHz BW, 25 Msample/sec- Higher BW makes no sense with meter leads.- Leave higher BW applications to "real" 2 or more channel scopes with scope probes.Like the 8208 also work with current mode.- clamp meter would be awesome...but perhaps struggle with screen sizeAt least twice battery lifeac/dc coupling switchable

author: janoc
author_rank: Super Contributor
timestamp: June 12, 2022, 07:16:33 pm
content: Quote from: DiTBho on April 14, 2021, 09:34:05 pmMore like rebadging and selling under their own brand. Completely common.And I wouldn't touch FNIRSI anything with a bargepole. Complete waste of money.

author: janoc
author_rank: Super Contributor
timestamp: June 12, 2022, 07:22:04 pm
content: Quote from: ledtester on April 14, 2021, 05:13:28 pmWell, specifically that one is pretty useless because there is nothing there to extend the duration of short pulses so that one can actually see them.The probes of old had a monostable flip-flop for that. Another option that I have found and built some 30+ years ago used a binary counter with 4 LEDs for this (probably a 7493 TTL chip). If you saw the counter state change, it told you not only that a pulse (e.g. a memory access strobe) has arrived but also how many of them. That was useful to debug e.g. switch bounces or my Didaktik M hacks (Slovak ZX Spectrum clone). Oscilloscope was an unaffordable luxury for me back then.