40,000 Count Multimeter under $50 - HoldPeak HP-770D - Page 1
Forum section: electronics / testgear

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 11, 2023, 11:55:59 pm
content: https://www.aliexpress.com/item/32983003087.htmlThis multimeter appears to have been out now for over 4 years now with essentially no attention on the EEVblog for hobbies. Per the linked video, it seems incredibly accurate for the cost (measuring down to 1uv) but lacks the safety features of a Fluke.Anyone on the forum have one? I was thinking of buying a few more Aneng 8009's (~$25) but for double the cost, I get 4x the counts (9999 count vs 40,000 count) and additional features. Opinions for hobby use?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 12, 2023, 03:09:40 am
content: everything is said in the video .... and seeing the fuses ....... notother threadhttps://www.eevblog.com/forum/testgear/holdpeak-hp-770d-issue/

author: Swake
author_rank: Frequent Contributor
timestamp: September 12, 2023, 04:42:44 am
content: If 'hobby' means you're never going to exceed measurements of about 50 V then it is good enough. Above that it is not safe. This is valid for all cheap DMM's. I've got to use an Aneng AN9002 sometimes and, while it is actually very nice for the price, I will not approach it to anything like mains voltage because if I make just one wrong move it's potentially the last one I'll ever make.Sounds likes this will be your first DMM. Don't give the specs and features too much importance. What you really need is a stable meter giving repeatable measurements. Repeatability is much more important than absolute accuracy or precision. Example: if you measure a value you want it to be in the ballpark of what you expect, that is close enough, you likely only need it to be within 2% or so. Any meter can do that. What you do care is that next time you measure the same value it effectively shows up as the same value so it gives you trust in what you measure and can be compared to another measurement.Off course it is nice to have 0.1% accuracy, but you don't need that. Same for anything less than 10 mV, you don't care. And when you start caring about these things you need a much more elaborate lab.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: September 12, 2023, 04:57:33 am
content: have one of this"Incredibly accurate" probably quite exaggeratedit has microvolts, but shorted it shows -7 microvolts now. usually it off from 2-3 LSN to 5-7 depending what you measure. limit 42000 useful to work with batteries where around 4V. (vs aneng 9999 )To turn on backlit you need to stick an electrical tape on the top center , where the sensor is located.speed is average \ mediocre - especially basic resistance algorithm switching down step by step ....So overall it is an average thingi .My daily usage is overclocked owon b41t+ (with 8M crystal instead 4m) - it measures any resistance 0.4 sec delay - very fast , useful if you need to find one in a haystack. it 22000 but precise to 1 LSD ; it a bit off more as i add more tvs diodes, thermistors , varistors. GTD.

author: magic
author_rank: Super Contributor
timestamp: September 12, 2023, 07:01:27 am
content: Quote from: LooseJunkHater on September 11, 2023, 11:55:59 pmCan't be assed to watch the video.Does it actually measure voltages like 1μV or -3μV or does it round everything less than ±5μV to zero in order to hide its offset voltage?This meter has been reviewed at lygte-info.dk and I remember finding something about it that made me prefer the Aneng AN870 as a cheap, high-ish resolution handheld.

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2023, 08:36:53 am
content: I saw the video and indeed it has got the 1uV resolution, no rounding around +/-5uV (stepping from 0 step 1uV shown)..Usable like null meter or something like that, imho..BUT, the 1.2V reference there is the LM385-1.2, afaik, and the input dividers are discrete resistors..

author: magic
author_rank: Super Contributor
timestamp: September 12, 2023, 08:48:51 am
content: Quote from: iMo on September 12, 2023, 08:36:53 amOK, so that's actually better than the Aneng rubbish. Even if there is offset, you can cancel it with the "zero" button, but you can't cancel cheating by the firmwareHowever, its millivolt range is low impedance - I think this is what I didn't like about it. I wonder if it could be modded perhaps?Quote from: iMo on September 12, 2023, 08:36:53 amThat's standard in similar meters.Resistors are not too bad and the meter has built-in resistor calibration function called the "ohms range"The voltage reference could possibly be upgraded and the meter recalibrated if you are really nuts.IIRC most of these meters have a cal jumper and usage of the cal mode is known and understood.editOn second, I'm not sure if you can use the ohms range to calibrate internal resistors against an external standard.The chip may have measurement errors, or may apply corrections programmed during factory calibration.

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2023, 09:36:58 am
content: at 6:26 starts the playing with the 1uV step around zero..I think a nice meter for use on the bench when messing with low-voltage low-power electronics (like max 24V and max 1A). It has got 10nA resolution, 1uV resolution, 10mOhm resolution (on the lowest ranges, sure) as I can see in the video. Would be great to know how to calibrate it, there is a standard 8pin flash storing the data..A pity they use the 9V block battery when the Vreg is 3.3V one inside, it takes 5.6mA (backlit leds off) what is not particularly low for a, say, 9V 250mAh NiMH battery, imho..At least a step-down switcher would be handy there with the 9V battery.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 12, 2023, 02:28:23 pm
content: Quote from: iMo on September 12, 2023, 09:36:58 amI actually think it's kinda nice that it uses a 9v battery with a 3.3v regulator. It allows the meter to be easily modded to use rechargeable lithium batteries in a 2s configuration. It'll have a longer battery life compared to the 9v cell and be rechargeable.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 12, 2023, 02:33:54 pm
content: Quote from: GigaJoe on September 12, 2023, 04:57:33 amNever heard of overclocking a meter before. I can see that the HoldPeak also has an internal crystal, so I wonder if it also can be overclocked? Aside from increased power consumption, will the overclock significantly impact the lifespan of the meter or effect measurement accuracy? There doesn't appear to be a lot of information on this; nothing on YouTube, and only one small thread on this forum.https://www.eevblog.com/forum/testgear/multimeter-overclocking/

author: coromonadalix
author_rank: Super Contributor
timestamp: September 13, 2023, 01:53:19 am
content: mmmmm the HY3131 is a 50 k count chip, maybe there could be some hack ?? eepom edit someting

author: GigaJoe
author_rank: Frequent Contributor
timestamp: September 13, 2023, 05:30:22 am
content: Quote from: LooseJunkHater on September 12, 2023, 02:33:54 pmbasic idea to change quartz , of course all related measuring changing as well, additionally stability on lower power voltage , can hiccup. some aneng works on 3x ( 12M) quartz . never play on expensive meters , due to mostly , complexity of cirquit, and no reason, if you already have cheap overclocked one.basic modding to add polymer caps with battery usually very noisy power line generated by chip itself, caps to vref , soldered connectors, something else like GDT

author: iMo
author_rank: Super Contributor
timestamp: September 13, 2023, 07:10:13 am
content: Quote from: LooseJunkHater on September 12, 2023, 02:28:23 pmSomething like this..

author: iMo
author_rank: Super Contributor
timestamp: September 13, 2023, 07:24:33 am
content: Quote from: coromonadalix on September 13, 2023, 01:53:19 am

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 13, 2023, 03:20:07 pm
content: Quote from: GigaJoe on September 13, 2023, 05:30:22 amNot sure what "GDT" is, but essentially just add some ceramic caps to the output of the linear regulator, monitor for heat (using a thermal camera), and see if it works? Can I essentially use any crystal which is faster than the original?

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 13, 2023, 03:34:25 pm
content: Quote from: iMo on September 13, 2023, 07:10:13 amExactly, except I'd personally do 2s (one lithium cell in each aa battery slot) due to the device using a (per video) 3.5v linear regulator.

author: magic
author_rank: Super Contributor
timestamp: September 13, 2023, 07:04:25 pm
content: Quote from: iMo on September 12, 2023, 09:36:58 amNow, this was probably the main reason I disliked it.Very wasteful, lousy battery life.Quote from: LooseJunkHater on September 12, 2023, 02:28:23 pmI would even consider single cell. The regulator is probably LDO and IIRC Li-ion delivers almost all its charge at more than 3.3V.The "battery low" indicator would need to be modded either way, because it reportedly trips at 8V.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 13, 2023, 07:13:17 pm
content: Quote from: magic on September 13, 2023, 07:04:25 pmI'd imagine it's just a simple voltage divider. Considering how few components exist on the PCB, I couldn't imagine this will be problematic to locate and modify.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: September 14, 2023, 03:09:34 pm
content: Quote from: LooseJunkHater on September 13, 2023, 03:20:07 pmcertainly,some dmm has 2 chips and 2 crystals - don't recommend touch those , most likely fail

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 15, 2023, 06:48:49 pm
content: Quote from: GigaJoe on September 14, 2023, 03:09:34 pmhttps://www.hycontek.com/wp-content/uploads/DS-HY3131_EN.pdfPage 20 of the schematic does make mention of an internal crystal oscillator. I wonder if the internal crystal oscillator has been disabled for this product so that an external one is used instead?

author: iMo
author_rank: Super Contributor
timestamp: September 15, 2023, 07:23:26 pm
content: That means "an internal oscillator for an external crystal"..There is not such thing like "internal crystal osc" in that chip..

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 18, 2023, 07:38:40 pm
content: Just ordered the meter for $44 USD. I'm expecting the meter to be pretty slow and if it is I'll attempt to overclock it.

author: iMo
author_rank: Super Contributor
timestamp: September 18, 2023, 09:53:05 pm
content: Quote from: magic on September 13, 2023, 07:04:25 pmThere is a diode in series with the + lead of the battery (see the pcb above), so it will not work with a single cell (unless you remove the diode). Btw. there are lipo 9V rechargeable with a lipo cell inside together with charger and switcher (step-up). Perhaps you can hack the switcher to produce 4.8V for example..

author: siealex
author_rank: Regular Contributor
timestamp: September 19, 2023, 12:33:49 am
content: These switchers produce enough noise to screw up the whole device.

author: geb
author_rank: Contributor
timestamp: September 19, 2023, 02:18:31 am
content: I've been fiddling with my HP-770D for months.If you're looking for great accuracy, even with calibration, you'll be disappointed. At least I am, with my one sample of this DMM.It initially drifted a lot. I replaced the LM385 with an ICL8069A and it got worse. Replaced the LM385, cleaned the PCB, removed any paralleled capacitors recommended by other forums. It's better now, drift-wise, but not perfect.Someone in a forum (here? Kazus?) recommended a 55000 count mod. I tried it. The linearity isn't great across any given scale, but with the increase from 40000 to 55000 it magnified the nonlinearity. There's a few (perhaps 4?) digits of inaccuracy as I go from 1V to 4V, but the inaccuracy increases to 21 digits at 5V. As in, depending on whether I calibrate at 1V or 2V or 3V or 4V, measuring 5V afterward is anywhere from 5.0006 to 5.0021. I apologize if I'm not perfectly clear on this one. I didn't keep any notes.It calibrates by using basically the same method as ZT-102, AN8002, and other cheap meters using a Hycon MCU. Close the jumper, turn on the unit and switch its dial quickly to ohms. Wait for its self-calibration to finish; it'll beep in mid-calibration and again at the end. Use HOLD and RANGE to decrease and increase, and SEL to advance. One word of warning: If you are displaying 40000 and you increase, the calibration routine will fail and you'll need to reload the EEPROM from a backup.Making a backup of the EEPROM: it's the same process as other Hycon MCU meters. You must move the dial away from the OFF position. You'll cause the MCU to run, and it'll interfere with your backup. Short out the outer two pins of the six-pin unpopulated inline connector near the calibration jumper, which will hold the MCU in reset so you can read the EEPROM.Like GigaJoe, my daily grab-and-go meter is an Owon B14T+ with the DCV 10-turn pot painstakingly calibrated. I didn't overclock -- I like how fast its autoranging is already. (It has a little nonlinearity across 2.2V-22V but I'm living with it.) I'd overclock my original ZT-102 if I knew how to change the divider on its Hz mode. I can't recall seeing an option for that in the Hycon EEPROM spec.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 19, 2023, 02:58:25 am
content: Quote from: geb on September 19, 2023, 02:18:31 amDid you recalibrate the meter after replacing the LM385 with the 8069?Why would removing paralleled capacitors help at all; wouldn't that actually have made things worse?Would replacing the SMD capacitors with name-brand low-ESR capacitors be a worth-while adventure, especially for the power rails?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 19, 2023, 03:04:24 am
content: in the end more problems than solutions for a mere 40$ ish meter .... is it or not worth it ??

author: iMo
author_rank: Super Contributor
timestamp: September 19, 2023, 10:11:50 am
content: Quote from: LooseJunkHater on September 19, 2023, 02:58:25 amEvery voltage reference has got some recommended in/out capacitors (because of stability). Some require large caps, some low caps.The smd capacitors - provided they are ceramic MLCC ones - are the lowest ESR already..The cheapo 20000/30000/40000 meters are basically with the "older" chips usually used as 4 digits ones (with the last 5th digit used as a "guard digit" and not showing it on the display). That allows to show stable readings and small none-linearity. Two my 30-40y old meters work that way, the last digit is not shown while the chips itself can do one digit more..

author: geb
author_rank: Contributor
timestamp: September 19, 2023, 02:34:34 pm
content: QuoteYes, I've recalibrated this thing a LOT. Basically after every time I mess with it.RE caps: I was following someone else's posted recommendation at the time. I think that one cap near the ADC wasn't on a supply rail and its removal probably made the most improvement. According to the original poster, low-ESR caps made a difference for him.I did a quick test of my HP-770D yesterday. In the morning, it read the 2.5V output of my AD584JH as 2.4984. At bedtime, it read as 2.4991. (The real answer is 2.49878-2.49882.) I gave the DMM a chance to "warm up" each time, and the room temperature varied by about 2°C between the two readings.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 19, 2023, 07:22:26 pm
content: Quote from: iMo on September 19, 2023, 10:11:50 amI never actually thought/knew about this before. Should I then essentially just ignore the last digit of my multimeter if I'm going for more-precise measurements?Quote from: geb on September 19, 2023, 02:34:34 pmI never thought/knew about this before, so thank you!Quote from: geb on September 19, 2023, 02:34:34 pmDo you have a source for this post/information, so that I could follow it?

author: geb
author_rank: Contributor
timestamp: September 20, 2023, 03:20:57 am
content: The thread over at Kazus discussing HP-770D capacitors... This has the capacitor replacement and also the EEPROM tweak for 55000 counts.https://kazus.ru/forums/showthread.php?t=120510QuoteI've seen people suggest that we should ignore the last digit. On some cheap meters, this is a safe strategy. But it isn't automatically true.Many of the lowest-cost meters were made with Hycon HY12P65. That chip is rated for 5000 counts but its ADC is 19-bit (2 ^ 19 = 524288). It's found in 2000, 4000, 6000, and 9999 count meters. HY12P65 is even used in Zotek ZT-209 and ZT-303* with firmware extending it to 19999 counts. My ZT-303 meter is quite accurate after mods and calibration, so I think kindly of the HY12P65.With a rating of 50000 counts, HP-770D's HY3131 ADC is better than HY12P65. But my sample of HP-770D is not impressing me.My modded ZT-303 (paralleled caps and ICL8069A voltage ref), and minimally modded ZT-102 (EEPROM 9999 limit based on AN8008), and even my newly arrived ZT-702S are pretty reliable on their last digit.If I had time, I would continue to study my HP-770D and try to figure out what's making it read so differently at one power-up versus another. I'd also like to know if other HP-770D owners have the same issue.* - The PCB's silk screen says it's an HY12P65, but who knows for sure?

author: iMo
author_rank: Super Contributor
timestamp: September 20, 2023, 09:48:27 am
content: Quote from: LooseJunkHater on September 19, 2023, 07:22:26 pmFor example the HY3131 is a "24bit sigma delta ADC" according to the DS. That is theoretically ~16million resolution (8.5 digits). You will not get such resolution in reality because of noise, drift, pcb design, etc. etc. (many other params are involved).The actual parameters (ie number of significant digits) are therefore mostly given by the external factors to the ADC. The cheaper parts and poorer design, the less digits you actually get. Therefore the cheap DMM vendors rather show less digits, as to have let the last digits jump all over the place. If you had access to the firmware of the MCU (which reads the ADC's values) you could introduce some averaging/smoothing to get a better output.

author: iMo
author_rank: Super Contributor
timestamp: September 20, 2023, 10:15:21 am
content: Quote from: geb on September 19, 2023, 02:18:31 amCould you point us on a detailed guide how to adjust the meter, plz?

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: September 20, 2023, 07:43:59 pm
content: Quote from: geb on September 20, 2023, 03:20:57 amI translated much of that thread and the associated thread.https://kazus.ru/forums/showthread.php?t=120130&page=3Translated from Russian to English:"I replaced all the stock ceramics 1206/0805 (X5R - 10/4.7uf) in the power supply connections of both chips with decent branded lowesr 100uF polymers and 47uF ceramics. The total capacitance for the +3V supply was about 250 µF instead of 40 µF.I am quite pleased with the result of the modification, the glitches have disappeared, and it works a little faster than the new one. The reference voltage measurements have not changed. Measurements of resistors <0.3 Ohm have become more adequate, for example, instead of 0.1 Ohm it was 0 Ohm, now it seems stable 0.07-0.08 Ohm."Associated image:https://kazus.ru/forums/attachment.php?attachmentid=160835&d=1614161531_________________________________________________________________________From this thread:https://kazus.ru/forums/showthread.php?t=120510"What was done:first I replaced the stock capacitors, 1206 turned out to suck Y5V, and 0805/0603 - X5R/X7Rhttps://kazus.ru/forums/showthread.php?t=120130&page=3#using 3V power supply I replaced the ME6208 LDO with a low noise LP2985-3.0"Ohm's was calibrated simply by using "closed probes" (I guess a near-zero ohm resistance connection?)"the diode measurement remains (it cannot be successfully calibrated), the direct voltage drop differs from brands like Appa607.71 by 1-2%.""For power supply, I replaced all the stock capacitor junk (all 0.1 uF were Y5V); LDO HE233 was replaced with low noise LP5907-3.3V; 4.7uf was added to the Icl8069 ion.""Replaced it according to the diagram, without recalibration:C1, C3, C17, C21, C23, C11, C13The next step was to increase the capacitance (add it in parallel) to the reference pins of the chips; recalibration was required, but the effect was noticeable - the device began to measure electrolytes 2-3 times faster.Add. Photos can be viewed herehttp://ixbt.photo/?id=album:66908"[I'm unsure what they mean by "diagram" (schematic), and I also don't see what values they changed for C1, C3, C17, C21, C23, C11, C13]There was also some other content about modifying the firmware values to increase the counts, but it's not very useful due to the poor translation.This thread appears to have the stock firmware (in case you modify the firmware and mess it up; I of course can't verify the legitimacy of the firmware):https://kazus.ru/forums/showthread.php?t=116225Direct link to firmware download:https://kazus.ru/forums/attachment.php?attachmentid=125109&d=1518199910

author: geb
author_rank: Contributor
timestamp: September 20, 2023, 11:22:41 pm
content: iMo, I've been asked to create a detailed guide for HY12P65 and derivatives. It's a fair bit of work to document it with all the side-topics and variations, and it might have to cover topics like "But I just want to calibrate this one favorite mode and be done with it -- what can I skip?" If my work deadlines would ease up, I could consider it. In the meantime, I don't think I have one favorite guide that you could apply to HP-770D.A translated DTM0660 datasheet might be worth reading as a starting point. Section 12 covers calibration. But change all of the 5's to 2 or 3 or 4. For example, in the first step while the selector is still pointing to the ohms scale, whereas the datasheet calls for 500mV and 50K sources, your first known-good reference sources for HP-770D could be 400mV and 20K, or 300mV and 40mA, and so on. Press SEL to skip ahead, HOLD to decrease, and RANGE to increase. And never hit RANGE when the count is above 39999!)LooseJunkHater, I've attached the screenshot from the same Kazus thread about the increase in counts. It requires editing the data EEPROM's contents, which means attaching to the EEPROM and reading/writing it. Change the bytes outlined in orange to the values in the picture. But please note that "firmware" in this case is merely the contents of the data EEPROM. It would be wonderful to get a copy of the firmware (I mean the program code), and/or a guide to the contents of the data EEPROM.

author: BillyO
author_rank: Super Contributor
timestamp: September 21, 2023, 12:37:57 am
content: Quote from: coromonadalix on September 12, 2023, 03:09:40 amIt's a hobbyist meter. It cost less than a set of fuses for a Fluke. If you are going to use this meter to check power entry switchgear in a NASA facility, you should have your head examined. If you are going to use it to measure the supply voltage your sending to the servos on your latest attempt at an Iron Man helmet, then it is a perfect choice.Not everyone needs a Fluke 289. Some people need to buy snow tires or pay the mortgage or buy medication for their ailing parents instead of dropping $1000 on a DMM where a $40 DMM will be overkill for their needs. TEE (Test Equipment Elitism) is a worse disease than TEA, because it only serves to belittle people.BTW, I'm just as guilty as the next guy, so take the above with a grain of salt.

author: bdunham7
author_rank: Super Contributor
timestamp: September 21, 2023, 03:41:04 am
content: Quote from: BillyO on September 21, 2023, 12:37:57 amBut you can get a perfectly decent real meter with real fuses for $40.https://www.lowes.com/pd/Klein-Tools-Non-contact-Lcd-Receptacle-Multimeter-10-Amp-600-Volt/5014355425Or if that is too basic or you want something more suitable for electronics, <$50.https://www.amazon.com/Multimeter-Auto-Ranging-Klein-Tools-MM400/dp/B018EXZO8M?th=1

author: BillyO
author_rank: Super Contributor
timestamp: September 21, 2023, 04:01:41 am
content: Quote from: bdunham7 on September 21, 2023, 03:41:04 amWhat makes "IT" real?Quote from: bdunham7 on September 21, 2023, 03:41:04 amInteresting for sure. Lots of neat toys added in to boot. One could argue about the lack of counts and the manual ranging, but neither are of terrible importance(?). Do you have a link to the teardown showing the $50 fuses? Not that it matters much for hobbyist use. But for $40, why not? It's just that the other choice is just as good in real hobbyist use, maybe even better for the added resolution and auto ranging, which we all really know is just a newbie feature.

author: BillyO
author_rank: Super Contributor
timestamp: September 21, 2023, 04:17:15 am
content: Quote from: bdunham7 on September 21, 2023, 03:41:04 amNice!I like the "Temp 600V" and of course it is "Orange". That's not yellow but it is orange.I have a full set of Klein electrician's tools. It's a nice kit. But I got this set of tools in 1992. They are awesome and still perfectly functional even after all these years. However, one of the screwdrivers would cost more to replace than either of those meters, so forgive me if I don't think that Kline have not sold out.Anyway, I guess that's not what we are talking about. So let me cut to the chase, what about either of these would be a compelling sell for the guy measuring the voltage going to his servos? Does he even have to spend $50, or will a nearly indestructible $19 Kaiweets KM-100 do just fine?

author: bdunham7
author_rank: Super Contributor
timestamp: September 21, 2023, 04:38:23 am
content: Quote from: BillyO on September 21, 2023, 04:01:41 amThere is another thread right now started by someone who accidentally shorted mains voltage with his Klein MM400 multimeter while the leads were in the 10A socket. He tore it down (unnecessarily) and it had blown the fuse. It uses 600V ceramic fuses, not the Fluke style, and they can be found for $3-4 from the right places, $12 from Home Depot or Zoro.https://www.eevblog.com/forum/beginners/i-was-an-idiot-and-may-have-destroyed-my-multimeter-any-way-i-can-test-it/msg5070877/#msg5070877QuoteIDK about the mighty Kaiweets, but the discussion in this thread seems to be about a meter with 'bang for buck' that seems to drift and generally not work well, making it's 40,000 counts sort of pointless. The Klein may have less counts but from what I know will be reasonably accurate, stable and durable. Now if your hobbyist is so broke from buying his ailing parents their medication and $19 is all he can swing, well I guess the Kaiweets will have to do. But it would be nice to have something that won't blow up in his face when he's trying to fix his poor parents furnace or something.

author: BillyO
author_rank: Super Contributor
timestamp: September 21, 2023, 04:22:22 pm
content: Yes, the meter under discussion may not be an ideal example of a low cost meter for hobbyist use. And those Klein's you linked to do look nicer. Probably a better choice just for the quality aspect even though they may lack a few features the hobbyist shouldn't really care about anyway.I've always been the kind of person (and of course this is strictly my personal perspective) that avoids buying a thing because of its whizz-bang features. I'd rather the money I spend go into things that make the basic functionality better. Just like those Kline meters. However, the fact that they have 600V rated fuses and supposedly can actually be used in a CAT III or CAT IV environment really means very little to me. I've never used one of my own meters in those circumstances and I'm nearly 100% sure I never will. I'm 95% a CAT I kind of guy and the other 5% would never go beyond 120V CAT II.So, why did I buy a Brymen BM786? Well, not for it's nice fuses or CAT ratings. I bought it because they have a reputation for quality, accuracy and stability. But now Dave relates they have higher than expected failure rates with the Brymens. I guess I just have to hope mine's not one of them. In the end, the fuses will probably outlast the meter.That said, back in the late1970's I bought a couple of "cheap Chinese junk" meter's off of Radio Shack (actually both are made in Korea). A Micronta 22-210 analog and a 22-198A 3.5 digit digital. They both have their original little 250V glass fuses in them and they both work and operate within their specs. The Fluke 8020b I picked up in the 1980's on sale (it was still more than twice the price of those Microntas combined) is long dead. It's little 250V glass fuse survived it. So much for buying expensive stuff.

author: bdunham7
author_rank: Super Contributor
timestamp: September 21, 2023, 04:57:34 pm
content: Quote from: BillyO on September 21, 2023, 04:22:22 pmExtreme longevity isn't necessarily a good indicator of quality, especially single examples. Extremely crude and simple things can often survive the longest. Supposedly after the human race has killed itself off, cockroaches will still be thriving. I have a Harbor Freight DT830 that has technically outlasted my first Fluke 289, but that is only because I never got around to making any mistakes that would blow the DT830 up. So I guess the DT830 is the DMM equivalent of a cockroach.

author: BillyO
author_rank: Super Contributor
timestamp: September 21, 2023, 05:11:53 pm
content: Quote from: bdunham7 on September 21, 2023, 04:57:34 pmYour DT-830 must one of the original "good" (consume salt now) ones. The last one of those I saw was without doubt the worst meter I have ever seen. Brand new out of the box the beeper had fallen off and even when re-attached you could not hear it over a gerbil sleeping 3 rooms away. The mA ranges did not work as the shunt resistors measured in the K ohms even though they were marked 1 ohm and 9 ohms. Right on the front it said the mA and lower ranges were fused with a 200mA fuse. On opening it to see what was rattling around it was discovered there was no fuse at all in it and where it was marked "500mA 250V fuse" (yes 500ma, not 200mA) there was just a trace shorting between the two solder pads. To top it all of, there was no socket for the transistor checker, just some bent metal clips on the PCB which could not be made to work.Yes a cockroach indeed. I ended up fixing everything except the transistor checker "socket", but you are 100% correct. It will survive due to non-use.

author: adamfrandsen
author_rank: Newbie
timestamp: February 25, 2025, 10:44:41 pm
content: What would be better for hfe matching - this meter, a dca55 or something else (dca 75 pro is a bit too expensive)… Thanks in advance!

author: BillyO
author_rank: Super Contributor
timestamp: February 25, 2025, 10:53:36 pm
content: Quote from: adamfrandsen on February 25, 2025, 10:44:41 pmA little component tester like the TC-1, T-7 or something along those lines would do a great job for very little money (~$20).

author: adamfrandsen
author_rank: Newbie
timestamp: February 26, 2025, 01:07:36 am
content: Quote from: BillyO on February 25, 2025, 10:53:36 pmOkay, was not sure they were precise enough…

author: BillyO
author_rank: Super Contributor
timestamp: February 26, 2025, 01:18:17 am
content: Quote from: adamfrandsen on February 26, 2025, 01:07:36 amYour ask is to do hfematching, so you don't really need a ton of precision, do you? These usually give hfeto single units of gain. How close do you need each device to be?More than likely what you really need for matching is repeatability. They are fine at that.

author: adamfrandsen
author_rank: Newbie
timestamp: February 26, 2025, 01:28:45 am
content: Quote from: BillyO on February 26, 2025, 01:18:17 amRight, I hear you about the repeatability. It ismfor a microphone circuit btw..