What to do with a ten-dollar multimeter - Page 1
Forum section: electronics / testgear

author: jonovid
author_rank: Super Contributor
timestamp: December 01, 2017, 09:46:13 pm
content: adding a display backlight to a junk-box multimeter. just for fun.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 01, 2017, 09:54:38 pm
content: Wow, that much? Save it for when you really need accuracy and use your your $2 meter (including batteries) instead.What sort of answer do you expect?

author: nanofrog
author_rank: Super Contributor
timestamp: December 01, 2017, 10:02:08 pm
content: Based on the title, those DT830 DMM's make great panel meters. Especially if they're free with purchase from a place similar toHarbor Freight(link = version with a backlight for $3.97).

author: beanflying
author_rank: Super Contributor
timestamp: December 02, 2017, 02:03:25 am
content: Safe uses and mod options for $10 multimeters.

author: Rick Law
author_rank: Super Contributor
timestamp: December 02, 2017, 04:51:20 am
content: Quote from: jonovid on December 01, 2017, 09:46:13 pmThe one you are showing is a $1 meter. So, carry on the trend, sell the $10 meter at $20. There should be some who would bite.

author: jonovid
author_rank: Super Contributor
timestamp: December 02, 2017, 11:27:54 am
content: I bought this DMM at a automotive accessory retailer in 2015 on special for just $9.95 .so I got ripped off by $7.95and yes i know about theits set at 500R or is it 400R.made the mod, and the video after seeing another display backlight moding video on youtube that had a somewhat poor end result.so the un-used DMM was sacrificed for the making of my mod video.I then added two angled & re-shaped lens, Ultra-Bright water clear LED's for better backlighting.at the expense of battery life. I welcome criticism of my work, as long as it, up's my video views.

author: bd139
author_rank: Super Contributor
timestamp: December 02, 2017, 12:14:24 pm
content: I've seen these sold for $20 or so on ebay. That I don't get. You can get them in the UK for $4!I've got an expensive bench and handheld DMM and I've still got a couple of these. They're quite useful for monitoring voltage/current in circuit. Keep it away from mains and high energy and they're quite useable. The annoying thing is the really low impedance of DC measurements of 1M but in low impedance circuits, who cares.As someone else mentioned, they make reasonable panel meters. Conversion instructions here:http://www.hanssummers.com/radiopsu.html

author: cdev
author_rank: Super Contributor
timestamp: December 02, 2017, 04:06:54 pm
content: Certainly, one can always use several meters. But sometimes, its good to give them to people.Cheap multi-meters that are still good enough to be safe make good gifts for people who are just starting out. People should give old no longer used meters away to people, young people especially, who will make good use of them.

author: IDEngineer
author_rank: Super Contributor
timestamp: December 02, 2017, 05:14:06 pm
content: Here in the States, Harbor Freight gives away these little DMM's "with any purchase". I have a stack of them still in the packaging, and every time someone asks me to help them come over and do something that requires a meter I take one with me to demonstrate, then have them use it to confirm they've learned something, and then LEAVE IT WITH THEM as a gift, free for nothing. This has two benefits:* My friends get smarter with time; and* I get fewer calls early on weekend mornings because now they have a tool to at least get started by themselves!I do give Harbor Freight credit for the free DMM, so they get some extra advertising out of the deal too. For the vast majority of non-electronic hobbyist homeowners, one of these little DMM's is all they will ever need.EDIT: Here is an online coupon for one of these DMM's, good through March of next year. Bring it up on your phone and they'll scan the barcode at the checkout.

author: bd139
author_rank: Super Contributor
timestamp: December 02, 2017, 05:38:18 pm
content: Until “dude, you know that meter you gave me? Yeah... well it blew up when I was sticking it across the mains in ohms mode and now I only have three fingers”.

author: kalel
author_rank: Frequent Contributor
timestamp: December 02, 2017, 06:59:02 pm
content: Safety of this meter and those like it has been discussed in depth by others, the main point is not to use it on mains or any device with risky voltage/current potential inside.With that said, I can ask the other question I had, how much do you have to spend to get that coupon?I'm just curious, as sometimes "free" is not free. For example, if the price of items purchased is already sufficiently higher comparing to other stores that sell the same thing, that even considering the value of the "free" item, you ended up paying the same, or more. Of course I don't know if that holds up in this case, sometimes it happens.That said, there are many variants from China, and they can differ in functionality and even build quality. They don't normally have the "on off" switch (off is on the range switch), at least I haven't seen it in any product image.When searching for some info a while ago, I found this page:http://all-sun.com/manual/Dt830_en.pdfFrom the document above, here are the differences in some versions:I have one of these, it comes with the continuity test beeper, and no (obvious) fuse inside or a fuse holder (but maybe the newer revision has a fuse, who knows):It is less than $3 on eBay.The main point of failure seems to be the probes. The wires are not properly supported, and can break and come out. The best moment to know about this is before the meter is used.If the probes on the meter you get with the free coupon look exactly the same, then adding some hot glue before the first use can be a quick (although perhaps not permanent) fix:What others here have showed me is that you can (with pliers) disassemble the probe/take out the needle part, and then properly attach the wire to the pin so it's held in place firmly, and maybe add heat-shrink for support. But adding some elastic glue to the end as support is definitely the easiest solution, just not the highest quality one.One positive thing about these meters is the display contrast. It is really great and easy to read from most angles.

author: kalel
author_rank: Frequent Contributor
timestamp: December 02, 2017, 07:31:43 pm
content: Quote from: bd139 on December 02, 2017, 05:38:18 pmWas this hypothetical person holding the meter in one hand? I still can't imagine measuring that way, but it might not be any more safe to have it blow up on a nearby object or floor, or hanging on something. Still, it could be safer.

author: Fungus
author_rank: Super Contributor
timestamp: December 02, 2017, 07:59:32 pm
content: Quote from: kalel on December 02, 2017, 06:59:02 pmYep, fill the end of the tubes with hot glue. Makes 'em last 100x longer, FWIW.

author: bd139
author_rank: Super Contributor
timestamp: December 02, 2017, 08:19:34 pm
content: Or you use them with Pomona 3782 grabbers which cost more per lead than the meter did

author: kalel
author_rank: Frequent Contributor
timestamp: December 02, 2017, 08:24:28 pm
content: I'm still curious in what the eventual replacement model of this meter will be. By replacement, I mean exactly the same price class, not $10-20, but $2-4 shipped.Will it have a different IC? More functionality? Better build quality? I think I can answer the last one.

author: bd139
author_rank: Super Contributor
timestamp: December 02, 2017, 08:26:23 pm
content: It won't change. It's based on a cloned ICL7106 IC. The design isn't that far off an early Fluke 802x series meter with every economy possible applied to it. It's a tribute to the ingenuity of the human race, even if it's a bit poo.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 02, 2017, 08:41:46 pm
content: Quote from: bd139 on December 02, 2017, 05:38:18 pmdude, you know that meter you gave me?Yeah... well the batteries leaked and the spew stained the wife's favorite piece of passed down furniture from the 1700s,the cat licked up the green jizz and died screeching for hours in pain,the kid wrapped the leads around the dog, it ran off in a panic under the house and died of slow strangulation.Now wife is pushing for divorce and the neighbor is threatening to sue my ass because the trapped dog is under his house decomposing and stinking,and because the meter is no go I can't even distract him with an offer for a free car battery voltage check or test his intermittent audiophool home theatre cables.Now I got the local animal welfare group investigating the matter, and the kid is on my case for a new dog and cat that look the same as the deceased.Next time dude, handball me a free meter that's wireless and solar powered... PLEASE !!!

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2017, 03:20:03 am
content: Quote from: Electro Detective on December 02, 2017, 08:41:46 pmok try Patent this.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 04, 2017, 12:07:40 am
content: Quote from: jonovid on December 03, 2017, 03:20:03 amAwesome!Upgrade the radio contoller with a small onboard solar power strip and supercap, and we have a winner !

author: beanflying
author_rank: Super Contributor
timestamp: December 04, 2017, 01:24:52 am
content: To finish off the build I can supply the correct switch

author: IDEngineer
author_rank: Super Contributor
timestamp: December 04, 2017, 03:16:41 am
content: Another use for some cheap DMM's like this is as an inexpensive ultra-low range DC current meter. This has been discussed here several times. With the meter set to DC volts (NOT current), the current flowing through the input resistance of the meter causes a voltage drop, which is then displayed. If the input resistance is (say) 1M, then each microamp will yield 1VDC across the input resistance. It won't be ultra accurate and may not even be super repeatable, but in a pinch you can determine its sensitivity against a known current and then do the conversion manually. If all you're doing iscomparingcurrents, you can even get by without knowing the absolute value and just compare readings. (Can you tell I've had to get by once in a while without lab grade equipment?)

author: kalel
author_rank: Frequent Contributor
timestamp: December 04, 2017, 03:59:35 am
content: I can't remember where exactly I heard or read that, but I think someone mentioned that the DT meters are fairly accurate. I could be wrong, and have no standards or calibrated meter to measure/compare with.

author: daybyter
author_rank: Frequent Contributor
timestamp: December 04, 2017, 04:44:15 am
content: I got me a 830d (with cont buzzer) for less than 3 bucks and at 5.00 V it is 0.01V off. At 2.5 and 10V it was spot on. Great little meter for breadboard work and such.I like the backlight mod! Great to see folks still tinkering with stuff and not just buy better devices. It might not be reasonable from a economical pov, but you can only learn from such projects and such knowledge has also some value.

author: beanflying
author_rank: Super Contributor
timestamp: December 04, 2017, 05:10:36 am
content: Nothing wrong with spending less $$. Just got to play safeOne of my favourite bits of test gear is my $7 evilbay component tester but I also love my 34401A

author: Fungus
author_rank: Super Contributor
timestamp: December 04, 2017, 05:21:13 am
content: Quote from: daybyter on December 04, 2017, 04:44:15 amYep. They measure quite well.Quote from: daybyter on December 04, 2017, 04:44:15 amThey don't last very long though. I'm not sure how much time/effort I'd invest in one.New topic: What's the oldest DT830B that gets daily use and is still 100% functional? Anyone...?

author: MosherIV
author_rank: Super Contributor
timestamp: December 04, 2017, 07:52:19 pm
content: Mine had light occaisional use for 10 years. Still works but the rotary switch is loose so it sometime does not measure correct values. Too much trouble, just moved on to my other dmms now.

author: 6PTsocket
author_rank: Regular Contributor
timestamp: August 26, 2018, 02:32:09 am
content: I accidently did that. It is easy to do if you use the wrong end of the knob. Apparantly quite a few others have done it. I am spoiled by my self ranging meter with on screen indicators. It did not blow up unless you count one microscopic SMD resistor. I replaced R13, 1500 ohms on the pc board and it is fixed. I just used a 1/4 watt leaded resistor. The ohms function is not fused but what do you want for free? It is not going to blow up, even on line voltage. However the test leads really do suck. I picked up some pretty decent ones on flea bay for $.99 delivered; far better than the leads on the freebee.Quote from: bd139 on December 02, 2017, 05:38:18 pmSent from my SM-G900V using Tapatalk

author: 6PTsocket
author_rank: Regular Contributor
timestamp: August 26, 2018, 02:39:38 am
content: Or spend $.99 delivered and get a far better set of of leads on fleabay The cables are heavier, the plug and probe have flexible strain relief. I figure a free meter is worth a 1 buck investment to fix the biggest problem.Quote from: Fungus on December 02, 2017, 07:59:32 pmSent from my SM-G900V using Tapatalk

author: 6PTsocket
author_rank: Regular Contributor
timestamp: August 26, 2018, 02:52:07 am
content: The object if an ammeter is to have the lowest possible resistance, so as not to reduce the current in the circuit you are measuring. The HF freebee has an input impedence of 1megohm on DC volts. You stick that inline and you will reduce the current to almost nothing and your circuit will not function. On the orher hand a high input impedence is desirable in a voltmeter so as to not load the circuit bring measured, to be almost invisible to the circuit. Better meters are almost always 10 megohmsQuote from: IDEngineer on December 04, 2017, 03:16:41 amSent from my SM-G900V using Tapatalk

author: Wolfgang
author_rank: Super Contributor
timestamp: August 27, 2018, 09:14:52 pm
content: ... give it to somebody you hate. Dont use it form measurements.Or maybe only for high risk stuff where it wont survive anyway.Play safe and buy something with proper protection !

author: cdev
author_rank: Super Contributor
timestamp: October 25, 2018, 12:07:15 pm
content: That meter is better than the first two meters I had (still have one) so I would not turn up my nose at one.Can't beat the price!