Hello folks,
I'm new to this forum. I have been following Dave's youtube channel for about 2 years now, but only recently decided to pour some money to get something really done in this field.
I'm not an electronic engineer. I'm from the other branch of engineering. So I'm certainly not an expert, and I need an advice from you folks.
So a little background, I'm interested in robotics & RCs. I'm about to start a project with the goals to develop an RC drone of some sort, for hobby purpose. And in the long term I also want to build a solid understanding of electronics, because that will greatly complements my knowledge from my own field. I want to start purchasing all the instruments that are required to build a simple robotics lab. A decent multimeter comes on the top of my list.
I haven't start this project yet, but I expect the multimeter would be used to measure the circuitry related to DC, servo, and stepper motor controller, and also the circuitry for the transmitter and receiver of radio signals. For the next step I also have an interest in Electronic Control Unit for a combustion engine, because who wouldn't love a jet-powered drones.
So there's a lot of things to learn, I don't know how long it will take but I have to start with the first step, getting familiar with electronics. Need a good meter for that. I'm willing to spend about $100 for a nice digital multimeter, and I already set my eyes on several models from reputable brands for that tier. Note that this price are the nett price in my country to get those meters to my doorstep. And all I can say is that the price here deviate pretty bad from Amazon as my source of reference.
I consider buying the following meters:
Extech EX330 $89 (only $60 on Amazon)
Amprobe AM-530 $151 (only $76 on Amazon) !!
Agilent U1232A $98 (costs $173 on Amazon) !?
Note that the price above are indeed the price from their respective authorized distributor. I'm sure they'll never sell any refurbished product. The Agilent one is probably an old stock that needs to go. They offered the deal to me after I reject the insanely overpriced Amprobe. I have to go straight to the distributor because I couldn't find those brands and models in any local reseller in my town.
Now of course the Amazon price is just for a comparison of how much money it is actually worth in the US. It excludes the shipping, customs duty, and other taxes (my country loves taxes so much), but as you can see the Amprobe one is really blowed out of proportion.
For the sake of comparison,
Fluke 87-V is only
$335 here - this is not from a distributor but from the most reputable local reseller that I believe won't sell any refurbished product. As much as this looks like a good deal (it's $387 on Amazon), I must not buy that because I run on tight budget. If I buy the fluke, then I'll have a hard time gathering the other essential stuffs like variable power supply, soldering station, etc.
I also went in and out of almost every electronics supply store in my town and found bazillions of rebadged-made-in-china-meters-that-won't-even-appear-in-google-search costs roughly around $30. I know Extech and Amprobe also do this rebadging thing, but I believe they have a tight standard that must be followed by the chinese manufacturers. Basically, most local resellers only have High-end DMMs like fluke and the rest are hordes of unknown brands @ $30. So no Extech, no Amprobe, no Brymen, no Uni-T, no BK Precision whatsoever. Either go with top of the line meters or go straight to the bedrock. Don't know why the local resellers don't stock these world-renowned brands, maybe I just lives in the wrong place.
Back to the topics, here's my findings so far about the three models of DMM mentioned above:
1. Extech EX330- Not true RMS.
- 4000 counts.
- Lots of features for its price range.
- Rugged design
- Winner of the $50 multimeters shootout by Dave.
- It's ready stock at the distributor's warehouse.
- Should be an affordable feature-rich DMM, however the distributor decided to sell it on premium.
- From what I read here, the quality control of Extech EX series "appears to be so bad that parts are coming loose inside some meters from the factory", and that the EX series should be avoided in general.
- The above link also says that the safety rating of CAT III @600V and CAT II @1000V is questionable due to the glass fuse which is rated at 250V. I'm not sure if this is really dangerous for me or not, again I am a newbie in this field. However, I don't think my multimeter will ever touch anything higher than 230V AC, which is my mains voltage in case I need to check/fix the power grid in my house (very rarely I guess). Most of the time I think I'll use it for DC voltage lower than 30V (I even considering to get only a 18V max DC power supply to save some money!)
2. Amprobe AM-530- True RMS.
- 4000 counts.
- Features on par with the Extech, minus the duty cycle (which I haven't done further readings whether I need that or not).
- According to by TechnologyCatalyst, the input protection seems to be the best among the three models, it got PTC, MOVs, huge resistor, and 2 ceramic fuses that are properly rated.
- (in my opinion) Very well-balanced in every aspects. My first choice before I heard about the price.
- It has to be imported from the US, that's one of the reason why the price is insanely high. Waiting time is non-issue for me though.
3. Agilent U1232A- True RMS.
- 6000 counts.
- It has LoZ feature, which is lacking in the 2 other models.
- Excelent build quality, very rugged design, the best of the three.
- Real, working, and useful "Hold" button.
- Real, working, and useful "Min/max/average" function.
- Smoothing features to reduce the effect of noise.
- Elementary data logging capability (can record up to 10 data onboard, can connect to PC via the IR-Bluetooth).
- Smoothing features failed to show a significant effect in by mjlorton.
- The IR-Bluetooth dongle not included in the package. Even the thermocouple & adapter is not included.
- In by Sh Kid, the PC connectivity via the IR-Bluetooth dongle doesn't seems to work.
- No mA range in the switch.
- According to this datasheet on page 6: "Notes for DC current specifications: 5. DC current between ± (0.6 mA and 1 mA) is not measureable on the U1232A and U1233A models". Another notes on page 7: "Notes for AC current specifications: 5. AC current between 0.6 mA and 300 mA is not measureable on the U1232A and U1233A models". So the DC current measurement range is between 60 uA to 10 A, except for the gap between 0.6 mA and 1 mA, which is not measurable. And for the AC current, measurement range is between 60 uA to 10 A, except for the gap between 0.6 mA and 300 mA, which also not measurable. Meanwhile the Extech and Amprobe can measure from 0.1uA to 10A without exception whatsoever.
- According to ,The quality of uA measurements is questionable. At 33:36 marks, mjlorton mentions about burden voltage. I don't really understand yet, but from what I heard the uA scale the Agilent U1232A has a burden voltage of 2.9V, which is bad for the quality of uA measurements.
At this point I really wish that I could get that Amprobe for $100. It looks like a well balanced meter , it is very decent in every aspect. However, does it make sense to get that for $151? It's twice the original price. I could push the limit to $151 but it really feels like a waste of money for me, knowing that in other countries that amount of money could get me something that is a whole lot better.
Agilent, on the other hand, looks like a bargain. Reputable brand, packed with features, excellent build quality, higher specs than the rest. But if it can't measure 600 uA - 1 mA DC should I even consider touching it? "
I have no idea what range of current that I will be using for my project. I'm a total newbie and just want to get started. If it turns out that my projects deals with currents between 600 uA - 1 mA a lot, then I will regret getting this Agilent meter so much. If anyone familiar with robotic & RC projects can give me an insight about this I'll really appreciate it. Also the burden voltage thing also bugged me, does it really bad for uA measurements?
And for the Extech, price is not that insane, spec looks acceptable even though it's not true RMS and the input protection seems bad. However some people here says the quality control is horrible like parts coming loose inside some brand new meter from the factory and so on. I really have no problem with Extech EX330 specs and features, but I don't wan't to get a defective product, and somehow the people here managed to assure me that the chance of getting a defective product is pretty high with Extech EX series.
And for the last, do I have to consider getting that Fluke 87-V for $335? If I do that, I'll have a significant delay for my project, because I won't have enough money to buy any variable power supply, even a crappy one. And what can I do without them? My shiny Fluke will just sit in my drawer for months waiting for the reinforcement to arrives :D. It's sad but I don't have that much money floating around right now.
So any advice will be greatly appreciated. I'd also like to thank you for spending your time to read this lengthy post.