Is this the bottom of the cheap multimeter heap?

[jimmc]

Almost all of these cheap meters are based on the ICL7106 chip; for a typical circuit see...
http://www.hobby-hour.com/electronics/dt830b-digital-multimeter.php
(link at end of 3rd paragraph)
Quality varies greatly, I have had some with no fuse and no trimmer for calibration!

Jim

[Chris_R]

I was going to come in here to gawp at how terrible the multimeter was but then I realised I've seen this before sold in Maplins in the UK.  I only remember it because they were selling them instore buy one get one free.
I mean who would need one of these crappy meters, let alone two!
http://www.maplin.co.uk/Module.aspx?ModuleNo=37279

[MrPlacid]

By the way ,2 years ago (or more) Fry's Electronics had in the paper selling an analog multimeter with mail in rebate for the same price. So the cost of the meter was the tax. I played with it for a while and with simple 9volt battery on different range and pop went the fuse

So I think that would be the bottom of the cheap multimeter.

[xrunner]

I needed a cheap DMM for my shed, so while at Harbor Freight I picked up the ubiquitous 7 Function DMM. This thread was started in 2010 so 14 years later we have this PCB. There is a pic at the beginning of this thread of the PCB from 2010. Interestingly it has the same brand of battery, a very "colorful" one indeed, nearly the same art work as 14 years ago.

As for performance it's not bad. Some testing shown in the pics. For $7 hey it works good enough for common uses around the house.

[Wallace Gasiewicz]

International Postal Rates are set by the Universal Postal Union and are set to be advantageous to third world developing countries.   
https://en.wikipedia.org/wiki/Universal_Postal_Union



Quote from: saturation on July 16, 2010, 01:01:11 am

Or whomever is making it in China is either efficient like we can never believe, the product is being dumped, its a loss leader to get you into the store, or its overstock like you would get in a dollar day buy.

China subsidizes many of their industries, its more accepted given their socialist roots.  For example, mail to the USA is nearly free, its the same cost as their local mail.  So this encourages a lot of direct shipping from Chinese merchants to 1st world consumers that you see on eBay.

[amyk]

The infamous DT830... there are actually many variants, some better than others.

https://www.eevblog.com/forum/testgear/t21463/

https://www.eevblog.com/forum/testgear/trashy-meters-redux/

https://www.eevblog.com/forum/chat/which-multimeter-or-company-started-830-design-case-that-is-so-widely-copied/

https://hackaday.com/2020/09/24/in-praise-of-the-dt830-the-phenomenal-instrument-you-probably-dont-recognise-for-what-it-is/

[tom66]

There's nothing all that wrong with one of these cheap multimeters provided they don't go anywhere near mains voltage or high energy things.  For messing around with Arduino circuits they're fine... maybe buy a second to double check any dubious readings...

[EPAIII]

At $9.99 it is a great, profitable sale. HF loves it.

$1.99 is probably what they pay for them, including shipping from China. So, not a loss-leader but probably a break-even-leader to get you into the store.

I have or have had at least two of them. One is dead. The other still works. I am not hard on equipment. That should tell you something.

Or whomever is making it in China is either efficient like we can never believe, the product is being dumped, its a loss leader to get you into the store, or its overstock like you would get in a dollar day buy.

China subsidizes many of their industries, its more accepted given their socialist roots.  For example, mail to the USA is nearly free, its the same cost as their local mail.  So this encourages a lot of direct shipping from Chinese merchants to 1st world consumers that you see on eBay.

I have bought many an electronic gadget for $1 at eBay with free shipping.

For example, this USB cable:

http://cgi.ebay.com/USB-DATA-SYNC-CABLE-WIRE-CORD-APPLE-IPHONE-3G-NEW-/250665636432?cmd=ViewItem&pt=PDA_Accessories&hash=item3a5cd61250

Here in the US, Harbor Freight has put a multimeter from Cen-Tech on sale for $1.99.
Down from the usual price of $9.99.

http://www.harborfreight.com/7-function-digital-multimeter-90899.html

It features a "fuse and diode" protected circuit :-)

I'm tempted to get one just to take it apart and see what $1.99 buys you...

Scott

As crummy as it probably is-- it serves to illustrate why there are no jobs in America. There's not one company in the US that could produce something like that for less than $30. By the time we satisfy OSHA, pay minimum wage, pay corporate taxes, buy product-liability insurance, provide health-care, and so forth, it just can't be done. Meanwhile, the goods we order are manufactured on a dirt floor. Our ideal country provides for everything but a job.

[Gyro]

A lot of those little meters give the impression that the designers actually tried to do a good job for the price. I have a tiny Skytronic one (a little different because it takes a smaller 12V battery) which is a perfect pocket meter for quick checks on potential bargain finds. It even has the correct CAT rating on the front!

https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg4160605/#msg4160605

[rhb]

I have a slew of them all over the place, some bought for $1.99 and some free.  They are my standard go to.  The. 3457A,  34401As and 3478As sit on the bench for fussy stuff.  The 3458A is awaiting repairs.

They occasionally die, but the fixes are pretty trivial.  Broken 9 V connector being the leading cause.  Calibrated they are 0.1% or better.  I use them for car and household repairs and testing battery cells.  I have a great many task specific toolboxes.  All the tasks that might need a DMM have one in the toolbox.

Love them!

Have Fun!
Reg

[fzabkar]

I see that some people have mentioned using these DMMs as panel meters. Are they using a battery as the power source, or have they found some way to utilise the power source that they are measuring?

[ledtester]

Does anyone have a guide to making these meters more accurate - perhaps by replacing the on board discrete parts?

[BILLPOD]

Good Morning  Slburris,  At the Harbor Freight link  you posted, the cheapest multimeter I could find was $6.99, and it looks like the same 'cheapy' they have always had. Were you looking at a special sale price?

[floobydust]

I see that some people have mentioned using these DMMs as panel meters. Are they using a battery as the power source, or have they found some way to utilise the power source that they are measuring?

Multimeter input COM(-) is not BATT(-) and you can damage the IC getting that wrong. So for panel meter use, you need isolated power, or have to make sure the common-mode voltage is reasonable. But there's no protection parts there, no coverage for CM voltage going awry, the IC will get blown up then.

A problem with these cheap DT830 multimeters is the protection components are usually left out, not populated. It depends on how cheap the build is. You have to use your eye and look for them.
A common happening is having it on Ohms but connecting to voltage like 24V. No PTC and maybe that lightbulb will cover it, but generally it will damage the DMM IC in these.

[tooki]

Good Morning  Slburris,  At the Harbor Freight link  you posted, the cheapest multimeter I could find was $6.99, and it looks like the same 'cheapy' they have always had. Were you looking at a special sale price?

Dude, it was a price (whether promotional or regular) 14 years ago. You can’t expect it to be the same today!

[tooki]

Does anyone have a guide to making these meters more accurate - perhaps by replacing the on board discrete parts?

They are already about as accurate as that fundamental multimeter design is capable of. You might be able to eke out a smidgen better long-term stability, but you could just twiddle the calibration pots every 5 years and do just as well.

[tom66]

Does anyone have a guide to making these meters more accurate - perhaps by replacing the on board discrete parts?

You can buy a significantly more accurate meter for about $20.  How much do you really value your time?

I suspect the inexpensive internal voltage reference in the main IC and the tempco of the cheap divider resistors will limit any accuracy improvement.  Short of replacing most parts, you're not going to improve the performance noticeably.

[xrunner]

Getting back to the original question for a second: I tried to see if there were deals on Amazon or AliExpress for a DMM less than what I paid for the HF DMM ($7).

Searching Amazon for the cheapest DMM, I couldn't get below around $9. But in the range $9 to say $15 there were some decent looking meters for casual use.

Regarding AliExpress, I am not a member yet. But when searching for DMMs there it gave me offers characterized as a "Welcome Deal". Taking that into account I could apparently get a very capable looking DMM from ANENG for a mere $0.99. Tempting ... 

[rhb]

Does anyone have a guide to making these meters more accurate - perhaps by replacing the on board discrete parts?

You can buy a significantly more accurate meter for about $20.  How much do you really value your time?

I suspect the inexpensive internal voltage reference in the main IC and the tempco of the cheap divider resistors will limit any accuracy improvement.  Short of replacing most parts, you're not going to improve the performance noticeably.

They are as accurate as they have the ability to display.  For $2 or Free they were a steal.  The more recent ones I got before they stopped giving them away don’t have a trimmer for setting it to a voltage reference.  A more serious limitation is the 1 MEG input impedance.  For better, spend more.

But they are decent DMMs for general household work or as dedicated V & A meters on a low budget lab bench.

Have Fun!
Reg

[Brumby]

The infamous DT830... there are actually many variants, some better than others.

Indeed.  I had some fun with my <$10 DT830 a few years ago.

The new front panel artwork:



The story of how it began and the iterative process of development is documented here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1689437/#msg1689437