Author Topic: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?  (Read 10647 times)

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Offline boffin

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EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« on: September 06, 2017, 04:17:16 am »
Dave tests the M328 (LCR-T4) model component tester.


 

Offline boffin

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #1 on: September 06, 2017, 04:20:25 am »
And Dave.  "M" is "madires" on the EEVBlog forum...

I've just got my PCBs back for spinning my own serial version of it (I'll be working on adapting the software in the next few weeks)

 

Offline Brumby

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #2 on: September 06, 2017, 04:56:05 am »
A much better assessment!  Well done Dave.

They aren't the be all and end all - but they are definitely worth the few dollars they cost!  (Even if the SMD pads are awkward to use.)
 

Offline bjcuizon

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #3 on: September 06, 2017, 05:16:17 am »
I was actually just looking forward to buying one from aliexpress. Here it is:
https://www.aliexpress.com/item/Digital-ESR-Meter-Mega328-Transistor-Tester-Diode-Triode-Capacitance-MOS-PNP-NPN-LCR-TESTER-METER/32776851185.html?spm=a2g0s.13010208.99999999.271.XyX0bD
It says below its page that the maximum measured value for the ohms measurement is 50M \$\Omega\$. How come the one Dave has just measures up to 10M \$\Omega\$? Is it firmware incapability?

*By the way, I'm not affiliated with that store above.
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Offline Brumby

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #4 on: September 06, 2017, 07:05:32 am »
There are dozens of different models of this out in the market - and this was shown in the video.  They are going to be differentiated by varying quality, capability and price.

The one Dave received was, it seems, one of the lesser models.  With the price for such a unit, you can't argue much.

.... and I am hard pressed to remember the last time I wanted to check a resistor over 10M.
 

Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #5 on: September 06, 2017, 08:14:04 am »
Most interesting is what a standard atmega328p (or similar) can do.
Are there any known projects that use some better hardware (like ADC/DAC etc)?
That way you can take it easy to another level, for just a few pennies extra.
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Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #6 on: September 06, 2017, 09:56:48 am »
And Dave.  "M" is "madires" on the EEVBlog forum...

The firmware of that clone is a modified k-firmware with a fancy output. The "M" in "MTester" is just a coincidence.
 

Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #7 on: September 06, 2017, 10:17:56 am »
WIth a current firmware the Transistor Tester supports:
- L/C/Rs
- special mode for low value L/Cs (k-firmware)
- diodes
- BJTs/MOSFETs/JFETs
- SCRs/Triacs (if they trigger with 5V and up to about 5mA)
- IGBTs
- PUTs/UJTs
- opto couplers
- rotary encoders
- PWM generator
- squarewave generator
- IR RC decoder (m-firmware)
- servo tester (m-firmware)

And there are several hardware options:
- Zener check up to about 30-40V
- frequency counter
- rotary encoder for user interface
- touch screen for user interface (m-firmware)

And I'm sure I missed some.
 

Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #8 on: September 06, 2017, 10:22:29 am »
Most interesting is what a standard atmega328p (or similar) can do.
Are there any known projects that use some better hardware (like ADC/DAC etc)?
That way you can take it easy to another level, for just a few pennies extra.

One of the key factors is that the MCU runs with 5V.
 

Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #9 on: September 06, 2017, 10:36:30 am »
Most interesting is what a standard atmega328p (or similar) can do.
Are there any known projects that use some better hardware (like ADC/DAC etc)?
That way you can take it easy to another level, for just a few pennies extra.

One of the key factors is that the MCU runs with 5V.
Explain?  :-//
Key factor of/with what?
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Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #10 on: September 06, 2017, 10:56:46 am »
Key factors of the design ;) WIth a 3.3V MCU you wouldn't be able to check as much components as with 5V without an external switching circuitry.
 

Offline RGB255_0_0

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #11 on: September 06, 2017, 11:30:09 am »
Seems you had your Snickers today Dave  :-+
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Offline Brumby

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #12 on: September 06, 2017, 03:01:58 pm »
Leave Dave alone.  He can't know everything (but missing that thread was a bit of a fail.)

He owned his ignorance - and proceeded to tackle the subject head on.  He has more than redeemed himself - in my eyes at least.
 

Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #13 on: September 06, 2017, 03:07:17 pm »
Key factors of the design ;) WIth a 3.3V MCU you wouldn't be able to check as much components as with 5V without an external switching circuitry.
Still don't see the point?

Plus you can easily use a lower voltage ucontroller with proper level-shifting and other techniques.
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Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #14 on: September 06, 2017, 03:50:41 pm »
Exactly! WIth a 3.3V MCU we would have to add several external components to be able to switch each probe pin and probe resistor between HiZ, Gnd and 5V. The current design with the 5V ATmega is very simple, another key factor.
 
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Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #15 on: September 06, 2017, 03:58:01 pm »
Exactly! WIth a 3.3V MCU we would have to add several external components to be able to switch each probe pin and probe resistor between HiZ, Gnd and 5V. The current design with the 5V ATmega is very simple, another key factor.
:o :o
Ok, I guess.  :-//
Don't really see why that would be an huge 'key factor' to be very honest.
Handful of components would maybe cost you a few cents, plus you get additional robust/sturdy I/O ports.
It's nice if 5V works out, but also not an huge deal-breaker if you can't IMO.
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Online Kleinstein

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #16 on: September 06, 2017, 04:58:12 pm »
The 5 V µC allows a super simple HW with direct interface to the µC - so no extra level shifter / amplifier needed.  5 V are just enough to turn on most MOSFETs and LEDs. A 3.3 V µC would need amplification and thus considerably more HW, as it would be 3 terminals working as input and output for both high and low currents. With a 3.3 V µC one would even consider the more traditional way with switch matrix and than dedicated drive and measure lines.

AFAIK the SW is more or less open source with extra functions added incrementally. In part it's rather tricky to measure very large an small resistors with such simple HW - even getting a ballpark figure is not simple.
With this rather good SW the cheap Chinese HW appeared - usually without giving credit to the original source.

However the super simple HW is also one of the big downsides: there is a chance to damage the µC with a charged cap or maybe ESD.

The capacitance is not tested at 1 KHz - it is more like a charge / discharge with the given resistors in the circuit.

The measured capacitance on MOSFETs might be high, because it is measured at low voltage. Data-sheet values are usually for a higher voltage.

The only thing disappointing is the lack of instructions.
 

Offline madires

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #17 on: September 06, 2017, 05:11:01 pm »
Yep, it would be nice if the clone sellers would add a note with the project's URL for documentation and firmware updates.
 

Offline Cerebus

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #18 on: September 06, 2017, 05:37:20 pm »
Yep, it would be nice if the clone sellers would add a note with the project's URL for documentation and firmware updates.

Which is?
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Offline Brumby

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #19 on: September 06, 2017, 05:39:27 pm »
Yep, it would be nice if the clone sellers would add a note with the project's URL for documentation and firmware updates.

Which is?

Good point.

I think it would be good to include that in this thread.  I've found a lot of EEVblog gets indexed on Google - and people looking for some info could easily end up here.
 


Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #21 on: September 06, 2017, 05:54:31 pm »
However the super simple HW is also one of the big downsides: there is a chance to damage the µC with a charged cap or maybe ESD.

The measured capacitance on MOSFETs might be high, because it is measured at low voltage. Data-sheet values are usually for a higher voltage.
Those are a few things I was referring to.
5V is the bare minimum.

Don't get me wrong btw, I am not saying it's crap, on the contrary.
I just don't see why 5V is "a key point".

That being said, I think it wouldn't be so difficult to lift this project to the next level.
With a few addons that means you can actually get very reliable results.
In my opinion the software is pretty decent in that side, but the HW could just use a few more bits.
That way you can easily come up with something that's being close or even equal to professional gear for just fraction of the price.
But maybe some people like to keep it simple and am I to ambitious?
I just see potential that's not fully being used.
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Offline firewalker

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #22 on: September 06, 2017, 06:23:54 pm »
If I am not mistaken there is calibration for this? Shorting the three probes and starting it? I could make more accurate. Mine is spot on compared with two flukes DMMs.

Alexander.
Become a realist, stay a dreamer.

 

Online Kleinstein

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #23 on: September 06, 2017, 07:50:48 pm »
Building a more accurate / capable version would likely mean changing the concept. With higher voltage one can no more use the digital IOs with tristate. So one would need kind of external multiplexers (e.g. 4 channels 3:1 mux) to connect measurement functions to the terminals. With dedicated channels for ADC and driving one could have higher resolution ADC / DAC or current source. However the software would likely need to be rewritten in many aspects. The software might be similar, but the HW would be considerably more parts. The next step up would be something like 5 more chips.
 

Offline b_force

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Re: EEVblog #1020 - Is A $7 LCR / Component Tester Any Good?
« Reply #24 on: September 06, 2017, 08:19:37 pm »
Building a more accurate / capable version would likely mean changing the concept. With higher voltage one can no more use the digital IOs with tristate. So one would need kind of external multiplexers (e.g. 4 channels 3:1 mux) to connect measurement functions to the terminals. With dedicated channels for ADC and driving one could have higher resolution ADC / DAC or current source. However the software would likely need to be rewritten in many aspects. The software might be similar, but the HW would be considerably more parts. The next step up would be something like 5 more chips.
I don't think you would need to use an higher voltage on all aspects.
But I see your point, although I doubt if you would 'completely' change the concept.

It's nevertheless doable, and I think worth a shot.
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