I've heard from others that Brymen is a good meter. I can tell you that Tenma and like meters are often not in tolerance right out of the box, and they do not hold calibration that well. I can't say if Brymen does or not.
It comes down to this. If you depend on a reading at all, and do not send it for calibration every year (99% of you don't and will not spend the money), then buy a decent meter like a Fluke or Keysight. I know for a fact that very few of you will take the time to figure out the range of readings for a certain range to see how many counts the meter might be off. With the cheaper meters, even the last digit is a joke.
So go ahead and buy a cheap meter if you are determined to do so. But understand there are very good reasons a Fluke or Keysight costs what they do. When you take a reading with a cheap meter, ignore the last digit (that makes a 3 1/2 digit meter a 2 1/2 digit meter folks!). Learn to say the reading is "about" whatever figure you get on the display. Understand that the reading absolutely will become less accurate as time goes by.
I also know that even after reading my post, most of you will continue to quote the entire reading your meter reports. Hope springs eternal I guess. However, when you are setting bias current in an amplifier, please make sure that meter is at least capable of making the measurement you are attempting. Most cheap meters are not even though they appear to be. Just 'cause you have a reading doesn't mean it is even close to being the value you are seeing.
-Chris
It comes down to this. If you depend on a reading at all, and do not send it for calibration every year (99% of you don't and will not spend the money), then buy a decent meter like a Fluke or Keysight. I know for a fact that very few of you will take the time to figure out the range of readings for a certain range to see how many counts the meter might be off. With the cheaper meters, even the last digit is a joke.
So go ahead and buy a cheap meter if you are determined to do so. But understand there are very good reasons a Fluke or Keysight costs what they do. When you take a reading with a cheap meter, ignore the last digit (that makes a 3 1/2 digit meter a 2 1/2 digit meter folks!). Learn to say the reading is "about" whatever figure you get on the display. Understand that the reading absolutely will become less accurate as time goes by.
I also know that even after reading my post, most of you will continue to quote the entire reading your meter reports. Hope springs eternal I guess. However, when you are setting bias current in an amplifier, please make sure that meter is at least capable of making the measurement you are attempting. Most cheap meters are not even though they appear to be. Just 'cause you have a reading doesn't mean it is even close to being the value you are seeing.
-Chris
Chris has good points there for sure.
As for the Tenma brand and it's accuracy, I have a Tenma dual-trace scope that I ran a calibration check on the other week.
As to frequency, it came up reading a 1kHz sine wave at 1000.0054 Hz.
Other checks like voltage, etc, were within the same accuracy.
Not too shabby!
As for the Tenma brand and it's accuracy, I have a Tenma dual-trace scope that I ran a calibration check on the other week.
As to frequency, it came up reading a 1kHz sine wave at 1000.0054 Hz.
Other checks like voltage, etc, were within the same accuracy.
Not too shabby!
That's a DSO, so I would really hope it is close. I am surprised your frequency display was that accurate though. See if it has an accuracy for it's time base. There is zero chance your reading could be more accurate than that.
My gear is frequency locked to a GPS Disciplined 10 MHz oscillator with an error close to 5 x 10 exp -12 or -13. The frequency reading you just quoted is better than most ovenized oscillators and I doubt strongly the Tenma has one of those inside. As for voltage accuracy, I'm afraid you can't be that accurate. Look at the accuracy of an 8 bit A-D converter, in a perfect world that is about as good as it gets. So if your display shows you a figure like that, your instrument is lying to you.
I'm currently using a Keysight MSOX3104T, and it isn't as accurate as that. This is a $25,000 scope here in Canada and has a 12 bit mode for vertical. I have all the software options which adds a lot of cost. No way is a Tenma anywhere near that accurate!
This is what I mean. Just because something has a digital display doesn't mean that every digit actually has meaning. You have got to look at the accuracy specifications, the range you're on and the frequency you're at, then develop an error budget. In other words, how many counts can your display be in error? It isn't abnormal to see the number of counts exceed 10 digits in some situations. Your ambient room temperature is also important and will be part of the accuracy spec.
-Chris
My gear is frequency locked to a GPS Disciplined 10 MHz oscillator with an error close to 5 x 10 exp -12 or -13. The frequency reading you just quoted is better than most ovenized oscillators and I doubt strongly the Tenma has one of those inside. As for voltage accuracy, I'm afraid you can't be that accurate. Look at the accuracy of an 8 bit A-D converter, in a perfect world that is about as good as it gets. So if your display shows you a figure like that, your instrument is lying to you.
I'm currently using a Keysight MSOX3104T, and it isn't as accurate as that. This is a $25,000 scope here in Canada and has a 12 bit mode for vertical. I have all the software options which adds a lot of cost. No way is a Tenma anywhere near that accurate!
This is what I mean. Just because something has a digital display doesn't mean that every digit actually has meaning. You have got to look at the accuracy specifications, the range you're on and the frequency you're at, then develop an error budget. In other words, how many counts can your display be in error? It isn't abnormal to see the number of counts exceed 10 digits in some situations. Your ambient room temperature is also important and will be part of the accuracy spec.
-Chris
Well Chris, it isn't an expensive 'scope, it cost around $400 I think when I bought it, but I got it on sale from Newark/MCM in 2017 for $269.
It does what I need it for - simple testing, good accuracy, etc.
Being retired, I don't need a "high end" piece of equipment like was in the shop I ran.
Hi dotneck335,
Reliability is being able to count on it to give you some sort of accurate answer for years. Cheap meters don't do that. More expensive meters do. I'm sorry, but that is the reality of life. That is all I have said.
Hi wiseoldtech,
Cheap DSO's tend to lie to you. I only had an issue with the accuracy you quoted, which wasn't realistic. I am familiar with those units. Again, all I have said was to have realistic expectations of the answers you get from that equipment. So go ahead and use cheap instruments, but understand the limitations of that equipment. Also understand that their performance degrades with time. All of it does. Cheap stuff does not have the benefit of really good engineering or parts, so they vary quite a lot unit to unit and over time. In other words, you can't really trust them to be as accurate as their displays seem to indicate.
Just expect results keeping with the price points of the equipment. Do take the time to review the accuracy specifications and just for fun, work some out. I didn't buy my equipment because I like to spend money (I don't, I'm cheap). I bought it because I depend on those measurements being correct 10 years from now and beyond. Having a long history with various brands of test equipment has shown me the hard truths.
-Chris
We aren't talking about hundredths of a percent if you have read the specs between equipment. We are talking 0.5% to 1% for the less expensive meters, and they don't hold calibration, so they aren't even reliable.
Reliability is being able to count on it to give you some sort of accurate answer for years. Cheap meters don't do that. More expensive meters do. I'm sorry, but that is the reality of life. That is all I have said.
Hi wiseoldtech,
Cheap DSO's tend to lie to you. I only had an issue with the accuracy you quoted, which wasn't realistic. I am familiar with those units. Again, all I have said was to have realistic expectations of the answers you get from that equipment. So go ahead and use cheap instruments, but understand the limitations of that equipment. Also understand that their performance degrades with time. All of it does. Cheap stuff does not have the benefit of really good engineering or parts, so they vary quite a lot unit to unit and over time. In other words, you can't really trust them to be as accurate as their displays seem to indicate.
Just expect results keeping with the price points of the equipment. Do take the time to review the accuracy specifications and just for fun, work some out. I didn't buy my equipment because I like to spend money (I don't, I'm cheap). I bought it because I depend on those measurements being correct 10 years from now and beyond. Having a long history with various brands of test equipment has shown me the hard truths.
-Chris
Well Chris, as I mentioned, the accuracy of the scope was quite good enough for my use.
Playing a 1000Hz test tone from my test CD resulted in that scope reading, which is only a 5 year old scope.
I do a maybe once-a-year calibration check on my equipment and so far haven't had any issues.
I'm not the "fussy" type now that I'm retired and not held to "fanatics" demands, and it's nice to relax.
Had a Tenma, blew the a r s e out of it after about 3 months. Easily done, measuring DC resistance, next check high voltage but some numpty left it on resistance.... bang.
I now have two old Fluke 25's, bought the two for less than the Tenma cost. Same scenario,the Flukes laugh at such abuse, shrug it off whilst whistling nonchalantly. Also the Fluke 25 has a service manual with schematics available, priceless the one time one needed fixing. Schematic for the Tenma? In your dreams, the nearest I got was the DMM chip datasheet.
One other negative against the the Tenma. I'd be furtling about inside a valve amp chassis being carefull not to touch potentially lethal parts of the circuit when BEEEEEP!!! Auto switch off is a PITA and damn right dangerous when fault finding on high voltage equipment. If I leave a Fluke switched on over night by mistake, no biggy.
So, if your mucking about with high voltage,I'd recommend a Fluke.
Andy.
I now have two old Fluke 25's, bought the two for less than the Tenma cost. Same scenario,the Flukes laugh at such abuse, shrug it off whilst whistling nonchalantly. Also the Fluke 25 has a service manual with schematics available, priceless the one time one needed fixing. Schematic for the Tenma? In your dreams, the nearest I got was the DMM chip datasheet.
One other negative against the the Tenma. I'd be furtling about inside a valve amp chassis being carefull not to touch potentially lethal parts of the circuit when BEEEEEP!!! Auto switch off is a PITA and damn right dangerous when fault finding on high voltage equipment. If I leave a Fluke switched on over night by mistake, no biggy.
So, if your mucking about with high voltage,I'd recommend a Fluke.
Andy.
Last edited:
I have a Fluke 289. It is stable and reliable multimeter. After a while, I had to replace super-capacitor on the main board, as it got rusted and meter has lost date etc.
Last year I got an Aneng 9002 for 19euro who measure excellent and allow me to graph or make remote measurements via bluetooth.
These tools can not be compared, in reliability, safe etc, but for the price and what offer, Aneng 9002 is a tool to be considered.
Regards,
Tibi
Last year I got an Aneng 9002 for 19euro who measure excellent and allow me to graph or make remote measurements via bluetooth.
These tools can not be compared, in reliability, safe etc, but for the price and what offer, Aneng 9002 is a tool to be considered.
Regards,
Tibi
Attachments
Last edited by a moderator:
Hi NickKUK,
Cheap meters are only calibrated with a couple adjustments, no others are available. Individual calibration checks are simply not done. This is how it is. Over 50% of cheap meters I calibrated were way out of tolerance new out of the box as part of the pre-sales checks when I worked at Transcat. Many were unable to meet their performance specifications across all functions and ranges. This was documented by myself and the other calibration techs day after day. We used to groan when a cheap meter was presented for calibration as they represented more futile work.
Fluke and HP / Agilent / Keysight meters all had a factory calibration certification included (the more expensive ones did). All meters for those brands tended to fall well within specifications. Basic DC accuracy could be 0.05%, and that is very accurate. Older meters of those brands did tend to stay within tolerance. My HP 974A (I have three) meters are rated for 0.05% basic DC tolerance, and all three are still in tolerance. They are very old meters. My Fluke 85 is also still in tolerance. Not bad at all since they are over 20 years old now and have not required adjustment.
There was one brand I won't mention that had software calibration (called closed case calibration) that was accurate, but they would not maintain that accuracy and drifted. The company charged 1/2 the cost of the meter (that was their factory rate!) to adjust the meter using in house software. They often failed the second calibration interval (one year).
Oscilloscopes historically were not expected to be extremely accurate. Their value was more in showing the waveform accurately and giving you a reading of amplitude within about 2%, better for lab scopes. The most accurate readings would be the horizontal, or time scale. So generally speaking, a modern oscilloscope tends to be a bit more accurate, but it's use is really about time and approximate amplitude. The accuracy will be limited by the probe / scope combination, and the input divider - plus the rest of the active circuitry. So lots of room for errors to creep in. The probes for my scopes run about $275 each Canadian, and passive probes are limited to about 500 MHz. So when you're playing with a DSO and a $20 probe you really have to ask yourself how much to expect in the accuracy department.
So today's DSOs can possibly be more accurate than the older analogue equivalent scope, but they are often about the same accuracy once you figure in the probe. The more expensive digital and mixed signal scopes (MSO) are a lot more accurate, but you still can't expect extreme accuracy. Another issue to watch for is the sampling artifacts which can generate displays that do not represent the waveform that is actually there. For some waveforms I still prefer my old Philips PM3070 and PM3065, but when those are turned on, forget working on FM tuners. The entire reason for the MSO on the bench was to replace the three instruments needed to cover all my measurements. Cheaper digital oscilloscopes do not produce useable displays needed for looking at eye patterns used in digital audio. The Philips scope are perfect for that.
At the end of the day, you can certainly use inexpensive equipment. However, you have got to keep in mind that the readings from those are not very accurate, and the performance can deteriorate rather quickly over time. I do use cheap meters but check them against a good one (called a cross-check) before each session. I toss them when they are far enough out, but they do save a good meter from damage. That's right, they are disposable and untrusted.
If you depend on, or rely on a reading, you cannot afford a cheap meter. At least get one decent meter from Fluke or Keysight. A bench meter is the best, but at least something good. Then you can compare your cheap instrument to it to have an idea what the reading it gave you really was.
We all want to set bias current accurately (so many millivolts) and DC offset (mV again), or a regulator output voltage. We do the work ourselves to do a good job. Why go to that effort and depend on something that cannot be depended upon? Sending cheap stuff out for calibration is expensive, more than a good meter for a couple trips. So I know very few of us will calibrate their meter. Most of us assume best case from the reading on the box without ever even figuring out what that means for a couple ranges. Then you use it for a decade making those same assumptions.
Isn't that flipping crazy?
-Chris
You are correct.. Part of the accepted chain is factory calibration, then calibration confirmation before packing or shipping. These are two separate operations.
Cheap meters are only calibrated with a couple adjustments, no others are available. Individual calibration checks are simply not done. This is how it is. Over 50% of cheap meters I calibrated were way out of tolerance new out of the box as part of the pre-sales checks when I worked at Transcat. Many were unable to meet their performance specifications across all functions and ranges. This was documented by myself and the other calibration techs day after day. We used to groan when a cheap meter was presented for calibration as they represented more futile work.
Fluke and HP / Agilent / Keysight meters all had a factory calibration certification included (the more expensive ones did). All meters for those brands tended to fall well within specifications. Basic DC accuracy could be 0.05%, and that is very accurate. Older meters of those brands did tend to stay within tolerance. My HP 974A (I have three) meters are rated for 0.05% basic DC tolerance, and all three are still in tolerance. They are very old meters. My Fluke 85 is also still in tolerance. Not bad at all since they are over 20 years old now and have not required adjustment.
There was one brand I won't mention that had software calibration (called closed case calibration) that was accurate, but they would not maintain that accuracy and drifted. The company charged 1/2 the cost of the meter (that was their factory rate!) to adjust the meter using in house software. They often failed the second calibration interval (one year).
Oscilloscopes historically were not expected to be extremely accurate. Their value was more in showing the waveform accurately and giving you a reading of amplitude within about 2%, better for lab scopes. The most accurate readings would be the horizontal, or time scale. So generally speaking, a modern oscilloscope tends to be a bit more accurate, but it's use is really about time and approximate amplitude. The accuracy will be limited by the probe / scope combination, and the input divider - plus the rest of the active circuitry. So lots of room for errors to creep in. The probes for my scopes run about $275 each Canadian, and passive probes are limited to about 500 MHz. So when you're playing with a DSO and a $20 probe you really have to ask yourself how much to expect in the accuracy department.
So today's DSOs can possibly be more accurate than the older analogue equivalent scope, but they are often about the same accuracy once you figure in the probe. The more expensive digital and mixed signal scopes (MSO) are a lot more accurate, but you still can't expect extreme accuracy. Another issue to watch for is the sampling artifacts which can generate displays that do not represent the waveform that is actually there. For some waveforms I still prefer my old Philips PM3070 and PM3065, but when those are turned on, forget working on FM tuners. The entire reason for the MSO on the bench was to replace the three instruments needed to cover all my measurements. Cheaper digital oscilloscopes do not produce useable displays needed for looking at eye patterns used in digital audio. The Philips scope are perfect for that.
At the end of the day, you can certainly use inexpensive equipment. However, you have got to keep in mind that the readings from those are not very accurate, and the performance can deteriorate rather quickly over time. I do use cheap meters but check them against a good one (called a cross-check) before each session. I toss them when they are far enough out, but they do save a good meter from damage. That's right, they are disposable and untrusted.
If you depend on, or rely on a reading, you cannot afford a cheap meter. At least get one decent meter from Fluke or Keysight. A bench meter is the best, but at least something good. Then you can compare your cheap instrument to it to have an idea what the reading it gave you really was.
We all want to set bias current accurately (so many millivolts) and DC offset (mV again), or a regulator output voltage. We do the work ourselves to do a good job. Why go to that effort and depend on something that cannot be depended upon? Sending cheap stuff out for calibration is expensive, more than a good meter for a couple trips. So I know very few of us will calibrate their meter. Most of us assume best case from the reading on the box without ever even figuring out what that means for a couple ranges. Then you use it for a decade making those same assumptions.
Isn't that flipping crazy?
-Chris
"We all want to set bias current accurately (so many millivolts) and DC offset (mV again), or a regulator output voltage."
Now, what would change if the DMM is 5% off (which is a very high error) being not calibrated? For clarity I oversimplify matters a little and mention the extremes. With exactly 0 mV DC offset in reality this could be +/- 0.05 mV... With a 5V PSU either 4.95 or 5.05V. Safe and no issue. With a 24V PSU that would be 22.8V or 25.2V. I would not worry too much (I also like good tools and instruments). The times I had my professional stuff calibrated I haven't seen much correcting action, just verifying the values. This was with pro Fluke stuff.
If DIY electronics should be adjusted that precise then maybe the design is a little off
Now, what would change if the DMM is 5% off (which is a very high error) being not calibrated? For clarity I oversimplify matters a little and mention the extremes. With exactly 0 mV DC offset in reality this could be +/- 0.05 mV... With a 5V PSU either 4.95 or 5.05V. Safe and no issue. With a 24V PSU that would be 22.8V or 25.2V. I would not worry too much (I also like good tools and instruments). The times I had my professional stuff calibrated I haven't seen much correcting action, just verifying the values. This was with pro Fluke stuff.
If DIY electronics should be adjusted that precise then maybe the design is a little off
Last edited:
Hi jean-paul,
My point is that most people would be surprised to see a 5% accuracy, but it can be much worse than that. That is my point. As for a 24 VDC supply, 22.8 volts might be way out of tolerance, and may actually indicate a problem with the regulator
As an experienced person, you can make the call as to whether a reading is problematic or not, as can I. But most members are not professionals and cannot make that determination. Having a reasonably accurate reading isn't too much to ask.
At no point have I ever advised people buy the highest accuracy meter - ever. What I have said was to buy a reasonably accurate meter that will remain in tolerance. This is a hobby, and since a meter is a key instrument it isn't unreasonable to spend $200 ~ $300 on one. Look at other hobbies and you'll see people investing many times that amount on equipment. Tropical fish, engine work, sewing machines or quilting. You name it, it is expected to spend some money on decent equipment.
I think that indicating a really cheap meter is adequate is a real disservice to our members. The other thing I have said is simply that if you opt for a cheap meter (or whatever), recognise it is not reliable and the readings should be suspect. That's all.
Human nature with digital meters leads people to trust the entire number in the display as accurate. Part of learning about electronics to to understand the limits of our tools and instruments. It is part of our education. All I have done is to draw attention to he fact that the number you see can be significantly off. In some cases it doesn't matter greatly, but in others it really does matter.
No issues with 5% at all. But many cheap meters are not even close to 5% at those ranges.
My point is that most people would be surprised to see a 5% accuracy, but it can be much worse than that. That is my point. As for a 24 VDC supply, 22.8 volts might be way out of tolerance, and may actually indicate a problem with the regulator
As an experienced person, you can make the call as to whether a reading is problematic or not, as can I. But most members are not professionals and cannot make that determination. Having a reasonably accurate reading isn't too much to ask.
At no point have I ever advised people buy the highest accuracy meter - ever. What I have said was to buy a reasonably accurate meter that will remain in tolerance. This is a hobby, and since a meter is a key instrument it isn't unreasonable to spend $200 ~ $300 on one. Look at other hobbies and you'll see people investing many times that amount on equipment. Tropical fish, engine work, sewing machines or quilting. You name it, it is expected to spend some money on decent equipment.
I think that indicating a really cheap meter is adequate is a real disservice to our members. The other thing I have said is simply that if you opt for a cheap meter (or whatever), recognise it is not reliable and the readings should be suspect. That's all.
Human nature with digital meters leads people to trust the entire number in the display as accurate. Part of learning about electronics to to understand the limits of our tools and instruments. It is part of our education. All I have done is to draw attention to he fact that the number you see can be significantly off. In some cases it doesn't matter greatly, but in others it really does matter.
Hi I meant to say that when buying Fluke or similar quality the accuracy is simply OK. So calibration is a luxury item then (in DIY!). As these are more durable as well I consider this a win-win situation and then the challenge is to find these for an acceptable price.
One can not desire extreme high accuracy when buying cheap stuff. As usual there is no substitute for quality. Buy good, buy once
We call cheap equipment “indicators” here
One can not desire extreme high accuracy when buying cheap stuff. As usual there is no substitute for quality. Buy good, buy once
We call cheap equipment “indicators” here
Last edited:
I was thinking like you, anatech.
Afther looking on this video EEVblog #1007 - Is a $25 Multimeter Any Good? - YouTube I have purchased one Aneng 8008 and I was pleasently surprised to see how precise it is. Now I have one more Aneng 8009 and two Aneng 9002.
I do not consider these are cheap multimeters, I look on them as cost effective multimeters and with some small modification these can be made to measure even better.
Regards,
Tibi
Afther looking on this video EEVblog #1007 - Is a $25 Multimeter Any Good? - YouTube I have purchased one Aneng 8008 and I was pleasently surprised to see how precise it is. Now I have one more Aneng 8009 and two Aneng 9002.
I do not consider these are cheap multimeters, I look on them as cost effective multimeters and with some small modification these can be made to measure even better.
Regards,
Tibi
Last edited by a moderator:
Jump to this point EEVblog #1007 - Is a $25 Multimeter Any Good? - YouTube if you what to skip the "bad part". .
Regards,
Tibi
.Regards,
Tibi
Hi Guys,
I only talk about equipment i have direct, personal experience with, so just because I exclude a brand doesn't mean anything more than I have not dealt with them directly.
As for Aneng as a brand, all I will say is that it costs a minimal amount to build things that will retain accuracy. If you do not build equipment that way, it will not stay in tolerance. I haven't any clue as to what Aneng is priced like, but if it is significantly less expensive than Fluke or Keysight, I have doubts about long term accuracy. We don't tend to send equipment in for calibration, or replace it when it reaches a certain age. Therefore it makes zero sense to buy something without a track record, or less expensive than the average for a good meter and rely on it. That's all I am going t osay on an Aneng meter, or any other brand.
Hi jean-paul,
On that we agree completely.
I only talk about equipment i have direct, personal experience with, so just because I exclude a brand doesn't mean anything more than I have not dealt with them directly.
As for Aneng as a brand, all I will say is that it costs a minimal amount to build things that will retain accuracy. If you do not build equipment that way, it will not stay in tolerance. I haven't any clue as to what Aneng is priced like, but if it is significantly less expensive than Fluke or Keysight, I have doubts about long term accuracy. We don't tend to send equipment in for calibration, or replace it when it reaches a certain age. Therefore it makes zero sense to buy something without a track record, or less expensive than the average for a good meter and rely on it. That's all I am going t osay on an Aneng meter, or any other brand.
Hi jean-paul,
On that we agree completely.
The mod is presented here Aneng AN8008/AN8009 Modify For Better Accuracy Faster Readings – JackenHack
Regards,
Tibi
Regards,
Tibi
