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Just how good or bad can a $1.78 DT-830B multimeter from AliExpress be?

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factory:

--- Quote from: NoisyBoy on March 06, 2023, 05:25:43 am ---Since the 10A range is unfused with only a shunt, I wonder what would happen if it goes beyond 10A?  In the case of the HF meters, I afraid the probe wiring may act as the fuse, which can get ugly. 

The HF meters in the US is even more capable than the DT-830D+, as it can measure up to 750V AC, and 1000V DC!  If one is brave enough to try it with the provided probes.

--- End quote ---

Or just make your own sticker up for it  :-DD, example below from the TEA thread;


--- Quote from: Brumby on July 23, 2018, 04:23:13 am ---I've spent too much time on this - especially for what it is.  Justification for efforts up to this point: Entertainment value for EEVblog members, but I have to wrap it up.

Artwork is done.  Just have to go through the production process.



--- End quote ---

David

graybeard:

--- Quote from: J-R on March 05, 2023, 09:26:27 pm ---Of course these cost more than $1.78 to make and far more than that to ship; there is no free lunch.  The money comes from elsewhere.

--- End quote ---

It seems to be some sort of loss leader on the AliExpress iPhone app.   I do not see these deals on the web site.   You have to choose 3-10 of these "special" items and they claim you get free shipping.   Where I live I pay 10.5% sales tax, but Aliexpress adds about 18% for the tax.  I suspect some of that "tax" amount goes to cover the shipping.

When I bought the meter it was $1.78, but most times the offers are for $1.99, $2.99, or $3.99.   If you look at an image from the iPhone app today you can see the meter is $1.99.   I bought one of the $1.99 AppleWatch chargers for my wife and it works great.   



The meter I bought was defective, it shows a low battery all the time.   But you may get lucky and get a good one.  I have made for of these orders and "returned" three of the items as not described or defective.  Each time I am given a refund within a few minutes of requesting it.   The refunds are for the full price, bot the "sale price."    Look at the refund I got for the meter.  I paid approximately $2.14 with "tax" and was refunded $3.86, more than I paid.


Paul T:
The variant of this meter shown in the lead post can be made adjustable for calibration. R8 is a 1K resistor. By replacing it with a resistance network that achieves a range around 1k, you can fine tune it while the leads are attached to a precision DC voltage source.  For instance, a 900 ohm resistor in series with a 200 ohm potentiometer.  I chose to use a 1.5K (18B) fixed resistor in the R8 spot, and a 5K micro pot in the empty space beside it, because it was handy and produced a professional result. When the pot is around 3K in || with 1.5K, 1K is produced.

Paul T:
I took the time to add calibration so I could be precise with voltage readings for my 4-wire conversion.

By adding a powerbank charge board, tested good lithium cell from a e-waste GPS unit, and a LM317 constant current source set to 100mA, I am now able to make quick 4-wire checks on any number of things.  I have usb attachments to test cables, prong probes for PCBs and so on. The only feature I disabled was 10A mode.  The main unit functions on the 9V battery as usual.

The attachment shows checking a precision 100 milliohm resistor.  I just have to multiply the mV voltage reading by 10 to determine milliohms.

My point is these are not serious devices, but cheap enough to make inexpensive useful tools out of... so they are of some value.   All together I may have spent $3 on the meter and consumables, nothing else required a purchase except the test clips to make a 4-wire tester.  This meter and many others like it have plenty of room inside for extra circuitry for your application.

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