Thanks but if UNI-T wants to pay me what I would take is a brand new UT181B with a spare battery, hardened front end, scratch resistant LCD lens... The 181A has some great potential for us non electrical types. The 61E is never going to have the features I would want in a hand held. It can't even read basic temperature.
Thanks. The one thing I should have show is that I do not use a glue gun. Rather I just snip off a small piece from the stick is melt it with the iron.
I just picked up one of those same cordless dremels. it's a beast. I also got answer of the quick change cutoff wheels. was a hell of an upgrade from my old harbor freight special!
This is the 3rd Dremel tool I have owned. It's maybe 10 years old now. Corded type. I have a fair number of cutters but someone on EEVBLOG pointed the ones shown in the video. I picked up a couple of different ones and this is basically all I use now for circuit board rework.
HAHA, say no more! Same here. That Teflon cover for the current shunt was a Dremel job. Sadly, they can take a fair amount of abuse which causes me use them for things that maybe I should not, leading to a shorter tool life... I use those two blade mill bits a fair amount when working with metal. Ran one into the side o my hand once. The floor had a nice crimson color to it....
Thanks, Good Video always Mr.Joe Smith ! my first and second multimeter is UT61E (original revision, not Europe PCB design), EEVBlog BM235. so, this Video is very intrest to me.
I don't care it's a cheap meter with some issues, it's an underdog in my eyes :) Great work, as always. And when I think i have a meter (17B) sent for repair since October for some "burden" Ohm. Yeah...
Second highest temperature drift of the ones I looked at, one of the highest burden voltages, damaged with very low ESD event, no backlight, no temperature. It does have a higher count that most and data logging included. Personally, I have more use for that CEM meter but they raised the price.
Indeed you did! Planned for tomorrow. But there is a snag with the µCurrent Gold. Often when doing measurements, you want to log current draw from a CPU between sleep and running. Unfortunately the range from the µCurrent Gold isn't large enough, so you have to do it separately. When running, the CPU might draw 80 mA, but in sleep it uses only 40 µA. Maybe time to read up on chopper amps. Do an open source device.
I had looked at Dave's schematics. Looks like he's using some nice parts. Do you then connect the uCG to a meter to make your measurements or do you use some sort of logger? Does this device have the dynamic range and resolution you need? I take it this wide range of currents is what damaged it.
I have written a Python script that controls my DMM's and make logs in CSV format. Yes, You are probably right, I overloaded it. But the strange thing is, I've changed out the opamps which is the first thing you would suspect got busted. But I'm going to do a full autopsy tomorrow. :)
If you have some relays and the meter is good enough, you could just switch in different shunts. Make before break in software. You may even be able to just use the uCG and control it with relays (once its repaired).
I know what you have basically done, but i have a "Soggy brain day" + medications dont help, i dont think ill try repairing anything today, could end in big mistakes lol. Looks like you have improved that burden voltage no end :-D
Would have liked to switch in a different shunt. The one way to do this would have been to use the two free contacts from the selector switch to drive a couple of DPDT relays. But the space, complexity.... There comes a point where the UT61E is not worth investing this sort of time. It will never do AC+DC....
Hey its better than before. Even if you had space, i would not use relays, the contact resistance is not reliable, unless you buy expensive types. Your way worked, dont be too unhappy. Brain is working now lol.
When I started to look at this mod, I spoke with a few people about it and explained just how bad the design was and how easily it could be improved. But because it is so bad, it was never going to be all that great. I set my goals pretty low. The meter is still not going to get used for anything outside of these little demonstrations. The read goal with these mods is to give some insight on how the meters work. Relays are fairly common and still have their place. Reliability is something that is designed in, not normally left to chance.
I know you have to pay for good design, but i still like the usefullness of cheap meters, they have a use :-D I do understand multimeters as far as the methods used for measurement and the quality of reference resistors and vref used. But ive never bothered with burden voltage/effect, connecting any multimeter in series with a load will automatically change the load and make the measurement a lie if the meter is removed. Bugger aint it LOL.
Yea, don't get me wrong. No way I would drag my good Brymen into the garage. I have my cheap Mastech for that sort of work where I know things will get spilled and dropped on it or it gets dropped. Sometimes it gets hung by its test leads. It's not the life for a good meter and that sort of work I rarely need much more than the free meters offer anyway and I sure would not need it certified. If they only had temperature and a backlight.
IDK if you could answer this but worth a shot. So I have a bunch of meters. Fluke amprobe etc.. I'm trying to calibrate micro amp range on one but when I connect a series resistance and voltage that makes 10 micro amp on one meter when I apply a different meter I'm getting different measurements with different meter.
@@fly-lucky First, lets define calibration. It does not mean that any adjustments are made to the meter. Rather the meter is compared with a NIST traceable standard to make sure it meets the manufacture's specifications. It may come with a report and data showing how far out the meter is. Normally several measurements are made, not a single data point. So let start with what you are using for a standard? It sounds like you are just using a DC power supply with a resistor. This is not a constant current source and will vary based on the meters burden voltage. Consider that even the fuses will have a different resistance, let alone the shunts.... So assuming this is what you are doing, start with a good constant current source. You still can't calibrate the meters, but at least you could make measurements that are closer.
Thanks for the prompt response. I'm using a agilent 8904 sig gen and a 1kohm resistance+/- .5% sig gen has been checked for accuracy. My question is tho I dial in a voltage to that resistance to get exact 1micro amp but when I connect a different meter I get a different measurement. My question is is there something I'm not seeing that would cause this?? All meters been factory calibrated 4 months ago.
The difference in measurement can be an oder of magnitude off depending on the meter. I'm trying to closed case calibrate the micro amp range on an amprobe 37xr but trying to reference it to another meter I know is accurate is where I'm having trouble because of the difference in measurements.
joe smith liked his splenification like on this uni-t Meter 61E could you pass me the template schematics or have a link where I can get it? I would also like to know which of the good quality multimeter the extech and fluke are the best in protection? I speak in Porgues and I have translated to understand it! thanks in advance ! traduzido para o português. Mais uma vez meu UNI-T UT61E é modificado. Desta vez para reduzir a tensão de carga na faixa de uA. Ele tinha a maior tensão de carga de todos os meus medidores ao lado do HF livre. Podemos fazer com que tenha a menor tensão de carga de todos os meus medidores? Assista e descubra. joe smith could you pass me this scheme or the link for me to download it! thanks in advance !
You should never modify any handheld meter. The data that I have collected for the meters is available for free if you want to see which meters performed the best.
joe smith .thanks for answering me ! I do not intend to modify the test device but the diagrams are only for repair and replacement of parts when necessary! I already picked up several multimeters with roasted burned resistors not giving anymore to see component identification! I would like to know where to fix diagrams or diagrams of multimeters I think manufacturers do not make available to be in charge of authorized ones! if you can give me some test schemas thank you I have something on my google drive. I know how difficult it is to find manual diagrams on the net! or send me an e-mail. I'm watching your videos, it's really good! I'm an electronics technician at 23 years old! in Rio de Janeiro in Brazil!
To be honest i didn't think you could make anything more to that meter but you proven me wrong again. i kind of think you need to find another subject to ridicule and improve upon:P oh well, it was fun to watch though i have a question about a diferent meter. i don't remember if you still have one of those two ut139c but if you find one of those corpses could you answer me this: Is the input resistor devider in those meters frequency compensated in any way? and is that true rms converter bandwidth limited by the input stage or s it limited by the main ic and a stupid idea for a new episode By any chance could you show off what can you build from ad736 chip and what can you measure with it and how to squize out the best bandwidth from tha rms converter? I would like to make one of those converters into cheap multimeter rms attachment. in theory it is a good idea, but in practice there is a lot of things that can mess you up Mentioned parasitic capacity of input stage>>frequency compensation, input and output voltages and protection of that thing and yourself
Sorry but I no longer have a UNI-T UT139C. Two of these was more than enough for me. The 736 is a fairly common part. You could just copy one of the several on-line meter schematics. Personally, if you needed an RMS meter, they are inexpensive enough. You would be much further ahead, unless you are just doing for fun or education. In that case you really don't want me telling you how to do things anyway. Just start playing and see what you can come up with.
right now, me playing around with the datasheet of that chip, made me come up with a poorly biased but kind of working ad736 model out of dua opamp, 9 transistors, few diodes and resistors. i mentioned it because it would look crazy if you would show harbbor fraight freebie meter doing ac+dc rms measurment with a less than 10$ converter box., leaving more expensive meters in the dust
It's very kind from you for this video.
At this point I think Uni-T should be paying you. They could take your improvements and make a new model - the UT61J. :)
Thanks but if UNI-T wants to pay me what I would take is a brand new UT181B with a spare battery, hardened front end, scratch resistant LCD lens... The 181A has some great potential for us non electrical types. The 61E is never going to have the features I would want in a hand held. It can't even read basic temperature.
that's some very nice mod wire work!
i agree.
Thanks. The one thing I should have show is that I do not use a glue gun. Rather I just snip off a small piece from the stick is melt it with the iron.
joe smith ooooh neat idea. convenient and it keeps things cleaner. glue gun isng exactly a precision instrument.
I just picked up one of those same cordless dremels. it's a beast. I also got answer of the quick change cutoff wheels. was a hell of an upgrade from my old harbor freight special!
This is the 3rd Dremel tool I have owned. It's maybe 10 years old now. Corded type. I have a fair number of cutters but someone on EEVBLOG pointed the ones shown in the video. I picked up a couple of different ones and this is basically all I use now for circuit board rework.
joe smith oh ok. I have the cordless version. I mostly use it for small metal fabrication. and cutting bolts and sanding and polishing and.....
HAHA, say no more! Same here. That Teflon cover for the current shunt was a Dremel job. Sadly, they can take a fair amount of abuse which causes me use them for things that maybe I should not, leading to a shorter tool life... I use those two blade mill bits a fair amount when working with metal. Ran one into the side o my hand once. The floor had a nice crimson color to it....
Where did you get hold of the cutters for the Dremel?
Those ones I show came from Amazon. I paid less for those than one normal bit.
Thanks for sharing Joe excellent mod love your videos
Thanks, glad you are enjoying them.
This guy is capable to transform a Fluke 289 into a Fluke 389.
Thanks, Good Video always Mr.Joe Smith ! my first and second multimeter is UT61E (original revision, not Europe PCB design), EEVBlog BM235. so, this Video is very intrest to me.
The 235 was better than the 61E but you loose the res. That's one of the down sides to the 235. It's more for basic electrical work than electronics.
I don't care it's a cheap meter with some issues, it's an underdog in my eyes :)
Great work, as always. And when I think i have a meter (17B) sent for repair since October for some "burden" Ohm. Yeah...
Second highest temperature drift of the ones I looked at, one of the highest burden voltages, damaged with very low ESD event, no backlight, no temperature. It does have a higher count that most and data logging included. Personally, I have more use for that CEM meter but they raised the price.
Excellent job!
Thanks. Glad you enjoyed it. If there was more room in the meter, I would have tried to improve the higher ranges.
Great stuff, as always!
Thanks Jack, glad you enjoyed it. I thought is may inspire you to repair your EEVBLOG uCurrent Gold.
Indeed you did! Planned for tomorrow. But there is a snag with the µCurrent Gold. Often when doing measurements, you want to log current draw from a CPU between sleep and running. Unfortunately the range from the µCurrent Gold isn't large enough, so you have to do it separately. When running, the CPU might draw 80 mA, but in sleep it uses only 40 µA. Maybe time to read up on chopper amps. Do an open source device.
I had looked at Dave's schematics. Looks like he's using some nice parts. Do you then connect the uCG to a meter to make your measurements or do you use some sort of logger? Does this device have the dynamic range and resolution you need? I take it this wide range of currents is what damaged it.
I have written a Python script that controls my DMM's and make logs in CSV format. Yes, You are probably right, I overloaded it. But the strange thing is, I've changed out the opamps which is the first thing you would suspect got busted. But I'm going to do a full autopsy tomorrow. :)
If you have some relays and the meter is good enough, you could just switch in different shunts. Make before break in software. You may even be able to just use the uCG and control it with relays (once its repaired).
Theres some nice "Kynar 30awg" wire on Ali Express. Ag coated.
I know what you have basically done, but i have a "Soggy brain day" + medications dont help,
i dont think ill try repairing anything today, could end in big mistakes lol.
Looks like you have improved that burden voltage no end :-D
Would have liked to switch in a different shunt. The one way to do this would have been to use the two free contacts from the selector switch to drive a couple of DPDT relays. But the space, complexity.... There comes a point where the UT61E is not worth investing this sort of time. It will never do AC+DC....
Hey its better than before.
Even if you had space, i would not use relays, the contact resistance is not reliable, unless you buy expensive types.
Your way worked, dont be too unhappy.
Brain is working now lol.
When I started to look at this mod, I spoke with a few people about it and explained just how bad the design was and how easily it could be improved. But because it is so bad, it was never going to be all that great. I set my goals pretty low. The meter is still not going to get used for anything outside of these little demonstrations. The read goal with these mods is to give some insight on how the meters work. Relays are fairly common and still have their place. Reliability is something that is designed in, not normally left to chance.
I know you have to pay for good design, but i still like the usefullness of cheap meters, they have a use :-D
I do understand multimeters as far as the methods used for measurement and the quality of reference resistors and vref used.
But ive never bothered with burden voltage/effect, connecting any multimeter in series with a load will automatically change the load and make the measurement a lie if the meter is removed.
Bugger aint it LOL.
Yea, don't get me wrong. No way I would drag my good Brymen into the garage. I have my cheap Mastech for that sort of work where I know things will get spilled and dropped on it or it gets dropped. Sometimes it gets hung by its test leads. It's not the life for a good meter and that sort of work I rarely need much more than the free meters offer anyway and I sure would not need it certified. If they only had temperature and a backlight.
IDK if you could answer this but worth a shot. So I have a bunch of meters. Fluke amprobe etc.. I'm trying to calibrate micro amp range on one but when I connect a series resistance and voltage that makes 10 micro amp on one meter when I apply a different meter I'm getting different measurements with different meter.
Do I have to factor in the shunt of the meter and output impedance of my signal generator?
@@fly-lucky First, lets define calibration. It does not mean that any adjustments are made to the meter. Rather the meter is compared with a NIST traceable standard to make sure it meets the manufacture's specifications. It may come with a report and data showing how far out the meter is. Normally several measurements are made, not a single data point.
So let start with what you are using for a standard? It sounds like you are just using a DC power supply with a resistor. This is not a constant current source and will vary based on the meters burden voltage. Consider that even the fuses will have a different resistance, let alone the shunts.... So assuming this is what you are doing, start with a good constant current source. You still can't calibrate the meters, but at least you could make measurements that are closer.
Thanks for the prompt response. I'm using a agilent 8904 sig gen and a 1kohm resistance+/- .5% sig gen has been checked for accuracy. My question is tho I dial in a voltage to that resistance to get exact 1micro amp but when I connect a different meter I get a different measurement. My question is is there something I'm not seeing that would cause this?? All meters been factory calibrated 4 months ago.
The difference in measurement can be an oder of magnitude off depending on the meter. I'm trying to closed case calibrate the micro amp range on an amprobe 37xr but trying to reference it to another meter I know is accurate is where I'm having trouble because of the difference in measurements.
Nice video. It look like this is a precison instrument for measuring amperage.
Thanks. If it had another set of contacts in the selector switch, I would have done something different.
Still works? (UT61-E), thanks for mod with back light btw, gonna try that out.
Yes, that meter is still working. It is only used for these demonstrations. I am collecting long term drift data on it.
Can this meter be callibrated after the mod - for accuracy ?
I don't know why not. If required, it could even be aligned but someone would have to have the skills needed.
joe smith liked his splenification like on this uni-t Meter 61E could you pass me the template schematics or have a link where I can get it? I would also like to know which of the good quality multimeter the extech and fluke are the best in protection? I speak in Porgues and I have translated to understand it! thanks in advance ! traduzido para o português.
Mais uma vez meu UNI-T UT61E é modificado. Desta vez para reduzir a tensão de carga na faixa de uA. Ele tinha a maior tensão de carga de todos os meus medidores ao lado do HF livre. Podemos fazer com que tenha a menor tensão de carga de todos os meus medidores? Assista e descubra. joe smith could you pass me this scheme or the link for me to download it! thanks in advance !
You should never modify any handheld meter. The data that I have collected for the meters is available for free if you want to see which meters performed the best.
joe smith
.thanks for answering me ! I do not intend to modify the test device but the diagrams are only for repair and replacement of parts when necessary! I already picked up several multimeters with roasted burned resistors not giving anymore to see component identification! I would like to know where to fix diagrams or diagrams of multimeters I think manufacturers do not make available to be in charge of authorized ones! if you can give me some test schemas thank you I have something on my google drive. I know how difficult it is to find manual diagrams on the net!
or send me an e-mail. I'm watching your videos, it's really good! I'm an electronics technician at 23 years old! in Rio de Janeiro in Brazil!
If you are just looking for the schematic I used, Google UNI-T UT61E schematic.
To be honest i didn't think you could make anything more to that meter but you proven me wrong again. i kind of think you need to find another subject to ridicule and improve upon:P
oh well, it was fun to watch though
i have a question about a diferent meter. i don't remember if you still have one of those two ut139c but if you find one of those corpses could you answer me this:
Is the input resistor devider in those meters frequency compensated in any way? and is that true rms converter bandwidth limited by the input stage or s it limited by the main ic
and a stupid idea for a new episode
By any chance could you show off what can you build from ad736 chip and what can you measure with it and how to squize out the best bandwidth from tha rms converter?
I would like to make one of those converters into cheap multimeter rms attachment. in theory it is a good idea, but in practice there is a lot of things that can mess you up
Mentioned parasitic capacity of input stage>>frequency compensation, input and output voltages and protection of that thing and yourself
Sorry but I no longer have a UNI-T UT139C. Two of these was more than enough for me.
The 736 is a fairly common part. You could just copy one of the several on-line meter schematics. Personally, if you needed an RMS meter, they are inexpensive enough. You would be much further ahead, unless you are just doing for fun or education. In that case you really don't want me telling you how to do things anyway. Just start playing and see what you can come up with.
right now, me playing around with the datasheet of that chip, made me come up with a poorly biased but kind of working ad736 model out of dua opamp, 9 transistors, few diodes and resistors.
i mentioned it because it would look crazy if you would show harbbor fraight freebie meter doing ac+dc rms measurment with a less than 10$ converter box., leaving more expensive meters in the dust
Sounds like you are making some progress. You should post your project on EEVBLOG.