EEVblog #1335 - Miniware $70 DT71 LCR Tweezer REVIEW

[EEVblog]

Review of the new $70 Miniware DT71 LCR Tweezers, is it any good?
https://s.click.aliexpress.com/e/_dT6koqT

TLDR; It's not very accurate, doesn't have much resolution, limited ranges, accuracy issues between Auto and Manual modes, can't be used while charging, lose the custom charge lead and you are screwed, tilt head detection has a bit of an alignment issue, LED testing is limited, and the secondary measurements basically don't work.
But for $70 it's very handy and nothing else can touch it, and the probe design is gorgeous.
Absolutely no match for the much more expensive SmartTweezers.
Maybe they can fix some stuff in firmware to improve it.

[dr.diesel]

No go if you ask me, especially with the asinine charging setup.

[langwadt]

that it doesn't do auto polarity for LEDs could be good thing if you have to check if a bunch of LEDs are mounted the right way

I guess having two different blink frequencies for the different polarity could work too

[EEVblog]

that it doesn't do auto polarity for LEDs could be good thing if you have to check if a bunch of LEDs are mounted the right way

True, if you can't get visual confirmation.
But if machine placed then they are either all going to be correct or all wrong!

[EEVblog]

No go if you ask me, especially with the asinine charging setup.

It's the Achilles heel

[thmjpr]

Bidirectional is good for LEDs, not having it is quite annoying. Software can easily compensate if you wanted to test a row of LEDs (just have a setting for uni/bi or pulsed as you say).

Seed $59 (+~$10 ship): https://www.seeedstudio.com/Mini-Digital-Tweezers-DT71-p-4696.html
Taobao $55: https://item.taobao.com/item.htm?id=626966187557
Global specialty LCR-58 $90 (no LED test): https://www.tequipment.net/Global-Specialties/LCR-58/LCR-Meters/
Smart tweezers $120 (no LED test): https://www.amazon.ca/Pince-épiler-LCR-Reader-Basic-Compteur/dp/B07C7S9DG6/

I would buy just the tweezer portion and make some adapter leads for my DMM and LCR meter. Someone could even make a better "head" unit for it, but thats probably wishful thinking.

Some photos show a curved set of tips, but it only comes with the one tip pair included.

[Skashkash]

I think that 3 pin TRS connector is working against them for measuring. They need to tie the battery gnd (probably) to one of the tines.

So no differential. And unless they have a charge pump in the head, driving a bi-polar signal for leds is going to be tricky.

[tautech]

Smart tweezers $120 (no LED test): https://www.amazon.ca/Pince-épiler-LCR-Reader-Basic-Compteur/dp/B07C7S9DG6/

No diode test ^ so a waste of tucker !
Had a set of ST3's for some years longer than Dave and wouldn't be without them.
BTW ST3 tips can be stretched to 50mm if needed.....far wider than a DT71.

When/if they die these are the ones to get: https://www.smarttweezers.com/st5s/

$274 here: https://smarttweezers.3dcartstores.com/

[2N3055]

It looks kinda fiddly.. Not impressed...

[EEVblog]

Global specialty LCR-58 $90 (no LED test): https://www.tequipment.net/Global-Specialties/LCR-58/LCR-Meters/

I already have one of those on order, only just discovered it while editing this video.

[BrianHG]

So no differential. And unless they have a charge pump in the head, driving a bi-polar signal for leds is going to be tricky.

Why?  If each pin goes to a different IO on the MCU, you just make 1 IO high and the other low, then swap.

[tszaboo]

So the TL:DR is that it has good mechanics, and probably OK electronics, that is utterly ruined by firmware. They seem to not understand what a measurement instrument is supposed to do. Like what frequency to measure a capacitor. Not to mention, with that huge errors, I dont think I would trust a single number that comes out of it.

[Skashkash]

So no differential. And unless they have a charge pump in the head, driving a bi-polar signal for leds is going to be tricky.

Why?  If each pin goes to a different IO on the MCU, you just make 1 IO high and the other low, then swap.

Yeah, was thinking about that, and a three pin connector is just way too restrictive.
So I took a closer look at the videos and it appears that they are in fact using a four pin TRRS connector. Much better.  So ignore my last post.  They certainly could drive both tips anyway they wanted.,   

[chickenHeadKnob]

Folks haven't been commenting on the left/right display hypersensitivity to motion. This one thing can make it unusable.
My Miniware TS100 exhibited the constant erratic switching  into sleep mode bug. Made it infuriating to use. Then I  fixed it when I downloaded the opensource firmware.

[Kosmic]

Global specialty LCR-58 $90 (no LED test): https://www.tequipment.net/Global-Specialties/LCR-58/LCR-Meters/

I already have one of those on order, only just discovered it while editing this video.

The Global specialty LCR-58 really look like the Mastech MS8911 (same buttons, same functionalities), but the later one is around 48$ 

Not to be confused with the MS8910 that look the same. The MS8911 is a full LCR meter with testing frequency from 100Hz to 10kHz with secondary parameters.

[rsjsouza]

So the TL:DR is that it has good mechanics, and probably OK electronics, that is utterly ruined by firmware. They seem to not understand what a measurement instrument is supposed to do. Like what frequency to measure a capacitor. Not to mention, with that huge errors, I dont think I would trust a single number that comes out of it.

+1 to that. I am not impressed. Besides, I got Keysight's shielded tweezer accessory to my Reed LCR and it covers this with advantages such as 100kHz frequency range and miliohms of resolution.

[Microcheap]

The Mastech MS8911: http://mastech-group.com/products.php?cate=104&PNo=78#_ doesn't have the same cool looking and feel and has, at least on paper, worse accuracy specs but it seems to work well, inclusive doing in-circuit measurement and it's cheaper.

The only problem is that I can't find where to buy it that will deliver to my country.

[Kosmic]

Looking at the waveform they use for measurement I doubt you will ever see any interesting secondary parameters (ESR, Q, D). They are clearly not measuring impedance here.

[EEVblog]

Absolutely no match for the much more expensive SmartTweezers.

How are they improving over the years? Last time I used them they are pretty buggy, like showing 0.9V instead of 1V test voltage, forgetting settings after charging, and some other weirdness going on.

I had to switch to LCR Research tweezers, and so far I've yet to find anything I don't like them while being cheaper and less buggy.

I don't have the latest design unit.
The LCR research one does look good, btu the top model is not cheaper. They over a lower end models though, and at $169 and comes with a NIST cal cert is pretty darn good value though.

[SilverSolder]

The UNI-T UT116A and UT116C also have the ability to rotate the head in relation to the tweezers - at ~$20 - $30 ? they seem worth a look as well.

[Kosmic]

The UNI-T UT116C also has the ability to rotate the head in relation to the tweezers - at ~$55 it seems worth a look as well.

It's a multimeter in a tweezer form factor though. Not a LCR meter.

[2N3055]

Absolutely no match for the much more expensive SmartTweezers.

How are they improving over the years? Last time I used them they are pretty buggy, like showing 0.9V instead of 1V test voltage, forgetting settings after charging, and some other weirdness going on.

I had to switch to LCR Research tweezers, and so far I've yet to find anything I don't like them while being cheaper and less buggy.

I don't have the latest design unit.
The LCR research one does look good, btu the top model is not cheaper. They over a lower end models though, and at $169 and comes with a NIST cal cert is pretty darn good value though.

1+ LCR research. I have them now for almost two years and they work well. I use it all the time.
But they are expensive.

With LCR tweezers, next development is not more features and gimmicky stuff like autorotation, but simple design, decent tweezer part and lower prices.
DT71 has good price, and if they went to copy classic design like everybody else and made it have necessary functions and mid range accuracy (no need for 01-0,2 %) it would be hit..

[KE5FX]

The Mastech MS8911: http://mastech-group.com/products.php?cate=104&PNo=78#_ doesn't have the same cool looking and feel and has, at least on paper, worse accuracy specs but it seems to work well, inclusive doing in-circuit measurement and it's cheaper.

The only problem is that I can't find where to buy it that will deliver to my country.

I just bought one of these.  A frustrating piece of gear.  It performs much better than rated; at 10 kHz in manual mode it can measure down to the 1-10 pF range, rather than 600 pF as the specs suggest, and it can measure inductors down to the 100 nH vicinity.  But its failure to remember its control settings is a real hassle if you intend to use it in manual mode, and who the heck wants to see dissipation factor as the secondary parameter for capacitance measurement, rather than ESR?

The prong tips are oddly-shaped and don't grip components well, it takes way too much force to close the tweezers, and they don't open wide enough to measure most through-hole parts despite the notched prongs suggesting that's what they had in mind.

It's OK for the price... but it wouldn't have taken much more development to justify a higher price, let's put it that way.

[SilverSolder]

The UNI-T UT116C also has the ability to rotate the head in relation to the tweezers - at ~$55 it seems worth a look as well.

It's a multimeter in a tweezer form factor though. Not a LCR meter.

You are right, it is missing the Inductance function.  But it looks like it will do everything else, including auto detecting the type of component (R, C, D) - auto detect is in the UT116A model only apparently.

Some users may be able to live with the fact that they have to dig out another meter to measure inductance, in return for paying very little for what looks like a handy little item with a rotatable head?

[Kleinstein]

With SMD parts it is sometimes difficult to tell if a part is an inductor or resistor. So it makes sense to have at least a crude way to measure inductance.