I am starting this thread to debate the cheap multimeter. In another thread some questions were raised and instead of hijacking the other thread I thought I would answer the questions here and start a discussion.
The questions started out in this thread here:
https://www.eevblog.com/forum/testgear/multimeter-sale-too-good-to-be-true-mastech-ms8268-digital-acdc-automanual-r/msg260292/#msg260292A recap of the questions posed:
Why is a cheap multimeter a bad thing? I have a 15 euros one and honestly it does the job quite well.. It measures resistors, caps and voltages quite well... Why do i need a more expensive one? All the voltages I work with are <=12 and 90% of them <=5volts.. and if the voltage fluctuates a bit then I use my USB oscilloscope and problem solved ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Seriously, what is the problem with cheap multimeters?
Even if your multimeter is super accurate your components have tolerances of a 2%, 5% and even 10%, ... who cares about the 3rd digit?
- If you care then probably your design is not robust and will just work in your lab and with that particular IC ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
High voltages, seriously, do you ever work with voltages >=220V? I'd say we work with voltages <=24Volts! most of us probably don't need all that safety stuff...
- shall we do a poll?
In my opinion a cheapo multimeter should be good for 95% of us....
So if is safe to say that for anything that is not >=110V or that is high precision electronics, a cheapo multimeter will do the job?
I am rather surprised how many people here are encouraging people to buy rather expensive equipments without even asking them what do they plan to use it for!
If after watching the videos and reading the other discussions you still aren't sure why cheap meters are not worth buying we should have a discussion here to clear things up.
First, cheap meters do have their place, but they cant be too cheap. You can buy some really cheap multimeters for $5 or less. I hope I don't need to point out to anybody that these are going to be junk and will not be reliable in any way. So I will not try to disprove the "value" of really cheap meters.
So why are some relatively expensive meters pushed on people? Well if you do anything other than poking your meter leads inside battery powered and low power AC connected equipment, then you are beginning to expose yourself to some random hazards. These hazards can be lightning strikes kilometers away causing a surge on the mains, a bad appliance somewhere in your house causing spikes on your wiring, even a faulty transformer on the utility pole outside. In other words you are playing with some potentially very hazardous conditions when you start poking around house wiring and the power distribution box in the house. So if you are going to even consider doing anything like this then you better have a good safe meter. $15 meters are not going to cut it.
Now that we have dispensed with the garbage meters and the higher end meters, lets get on with talking about the "cheap" meters. Not all are garbage but all are not safe for poking around the mains. What are they good for? A cheap meter
can be a good meter for playing/working on the bench with low power experiments and equipment. There are caveats to this of course. Some cheap meters are really bad garbage meters hiding in sheep's clothing.
"I am only a beginner and I don't see why I need to buy a better meter". Unless you know what to look for then buying a cheap meter could be a bit of a random thing.
The really bad part about this is if the argument is that you are just a beginner and you don't need a great meter then you also lack the experience to know if you need a better or safer meter or if the one you are buying is any good at all. This is why if a person isn't sure what they will be doing with their meter then the best thing is to recommend a meter that will keep them safer while they learn and make mistakes.
"OK, so I promise to only use my meter for poking around inside battery operated things or clock radios and the like. So I will go buy that $15 meter I saw on ebay, ok?" Well it might be OK, maybe. If you can't afford to waste money, then you might be throwing away that $15 when/if that cheap meter falls apart in a few months. There is a saying; "Buy quality, buy once. Buy cheap, buy many times." But that is not the only risk to buying a cheap meter. If you are trying to learn and measure things, then the long term stability of the accuracy of the meter comes into question too. Sure, almost any brand new meter regardless of price will probably be within specification out of the box, probably. How will you know? Well if you are a beginner you will be less likely to catch any errors. Do you have any circuits that you are checking that require accurate readings, say something that will blow up if you feed it too high a voltage? That could cost you the price of a good multimeter in one error! If you are trying to learn and you get readings that aren't quite right you aren't going to learn the right things.
Cheap meters will not take a drop as well as a better meter. They might outright break apart or stop working, or worse appear to be work after but not show correct readings. Maybe it will show slightly incorrect readings or worse show no voltage at all when there really is. It is not fun having a live circuit when you think there isn't one.
This is not to say that expensive meters never fail and that all cheap meters are useless. I have a few cheap meters and they have a use in my car, or lying around for easy access to measure the state of some batteries, etc. They are useful to me even with my other expensive multimeters as extra meters for when I need to do multiple measurements at the same time. The ones I have I can cross check with my expensive meters and so I know when something is not right with them.
It is actually ironic. A person who wants a cheap meter to learn or to start out usually is the least qualified to make a good decision on how cheap a meter to buy or whether they should ignore the advice of more experienced people. If you insist on buying a cheap meter, then look for reviews from trusted sources first or discussions on the model you are considering. There are some relatively good cheap meters but they are very few.
For a better understanding of what to be concerned about read the following thread:
https://www.eevblog.com/forum/testgear/a-list-of-multimeters-that-do-not-appear-to-meet-their-claimed-safety-specs/If you do buy a cheap meter avoid the temptation to use it on higher energy circuits when something comes up "just once".