Design a New Precision LCR Tweezers with Much Lower Cost 【Shannon Tweezers ST42】

[ceut]

For AliExpress, I have simulated a new order for delivering in France, it seems to be OK for me, even the price and the shipping cost (it was about 15€ lower when I bought it for my 2023 christmas gift  ).

I don't really understand what is happening on their side, but I know they never had answers to real problem (example: I was having a problem with my Paypal account, I have asked them many times and I hae never had a single resolution, and after 1 month my problem has been fixed without them - I don't know how)

[valcher]

@ceut
When I ordered tweezers in the store, a warning came out - “you can only purchase one item.” I don't need two or more, I buy only for myself. The price of the tweezers was the same as yours. Now, if I go to the store under my account, the price is 40% higher, if a wife, then the price is low.
Most likely the product is limited and there are some temporary restrictions on accounts.

[mawyatt]

WRT making milliohm impedance measurements with any instrument. Getting Reliable Repeatable measurement results is difficult even for Bench Lab Grade LCR Meters.

We must remember that with a milliohm resistor with a 10ma test current, the measured voltage is only 10uv!! Even with a 1 amp test current this is only 1mv!!!

Don't think it's quite fair to be asking Tweezers of any kind to delve into this very low impedance area and produce very accurate and repeatable results since they likely can't produce enough test current to create a respectable DUT voltage for the measurement.

Of course we may be all wet on this as we don't know exactly how the measurements are conducted on various LCR type Tweezers!!

Best,

[Sparrow]

Regarding the mentioned battery discharge issue, I investigated the behaviour of the instrument on a daily base and finally, I'm pretty sure it was my own fault...
When not in use, I kept the tweezers in the supplied box while it also contained the folded "quick reference chart". Since the "joystick" button projects from the body of the tweezers, as long as there's only the foam padding opposite to it with the lid of the box closed, everything's fine. But if the relatively stiff paper of the quick reference chart presses against the joystick, it could very well depress it and cause the discharge problem. Investigating the chart more closely, I found traces of a depression right where the joystick would be if the chart is slided towards this edge of the box, so I assume this was actually the case.

From now on, I make sure that the chart is not covering the joystick when I close the box. No further problems observed since... 

So is the issue that the button being pressed turns the tweezers on, or that it just draws significant current by virtue of being depressed?

If the former - should be able to be fixed with a different, more robust power up method, e.g. move left, right, left, right or something else.

If the latter, then does anyone have a problem when it's in the leather case - does the case push the button?

[KungFuJosh]

It's fine in the leather case, I leave it in there 99% of the time. The leather case has a cutout so it doesn't mess with the power button.

The power button design is fine as it is, it would be weird if it was different.

[dibro]

I have no problem at all with using the leather case, Use it all the time.
But you have to take care that nothing is pressing in the case where the button is located.

[Shannon]

With the help of @Sorama, we finally solved the problem of order failure, and we are very sorry for the impact it caused.

We guess the specific reason is that the AliExpress platform launched a discount coupon activity, but the discount coupon was invalid, and then the order was closed.
At the same time, the setting of ST42 is that the store discount is only allowed once, resulting in subsequent orders:
1. When using the discount coupon, it will be prompted that the discount coupon is invalid.
2. If the discount coupon is not used, the order will be automatically closed.
It looks like that a problem within AliExpress was triggered, but they did not pay enough attention to it.
In the end, it seems that there is no problem between the buyer and the seller, but the order cannot be completed.

We modify the store discount using times, for those auto cancelled buyer can finish the order on Aliexpress platform now.

Thanks a lot for Sorama and valcher help

We found a bug in AliExpress, it caused us losses, but it seems that we will not get compensation or gifts like Shannon Tweezers :'(

[shapirus]

So I've just watched a review on the Zoyi ZT-MD1 LCR tweezers, this one:



One noticeable feature that it has is continuity buzzer. I can easily see how it may be handy when poking around at a circuit board under inspection: you won't have to reach for the regular DMM to test continuity when everything can be done using just the tweezers.

I think it might be nice to have this function in the ST42 too. As far as I understand, it should be fairly easy to implement it in firmware. The beeper is rather weak, but it may still be okay. It could be implemented as a configurable option to enable it in auto mode (and R mode as well), and the logic would then be simple: if enabled, then beep if we're in the manual or auto-detected R mode and the measured resistance is lower than say 10 Ohms.

[Martin72]

I don't know whether a continuity test function makes sense with the mechanically very limited path of the measuring tips.

[shapirus]

I don't know whether a continuity test function makes sense with the mechanically very limited path of the measuring tips.

"...let's see if this SMD cap is shorted"