Looking for cheapo multimeter like DT830, but with serial link - Page 1
Forum section: electronics / testgear

author: mrflibble
author_rank: Super Contributor
timestamp: December 08, 2013, 03:51:21 pm
content: Subject says it all really. I'm looking for some cheapies like the DT830/838. Those go for ~ $4 on ebay. For some uses these are good enough for the job, if only I had several more for simultaneous measurement + logging.One solution would be to get a bunch of DT830's, and then add an msp430 + optocoupler. Have the msp430 decode the lcd driver to get the digits, etc. But why bother if there is already a cheapo meter out there that does have a serial link, but for some reason you just can't find it.Sooooo, I am hoping that in fact there is already a cheapo meter out there that does that (crap-but-good-enough-for-the-job DT830 specs + serial link). Oh yeah, doesn't have to go to 1000V. I mean, it's not as if I would even consider measuring that with a meter like this.

author: danb35
author_rank: Contributor
timestamp: December 08, 2013, 05:15:52 pm
content: This is the cheapest one I know of with data logging:http://www.ebay.com/itm/Digitek-DT-4000ZC-TekPower-TP4000ZC-Data-Logging-Multimeter-with-Temperature-/200912705694?pt=LH_DefaultDomain_0&var=&hash=item2ec754989e.See alsohttp://www.amazon.com/TekPower-TP4000ZC-RS232-Interaced-Ranging-Multimeter/dp/B000OPDFLM/ref=sr_1_2?s=lamps-light&ie=UTF8&qid=1386522933&sr=1-2&keywords=digitek

author: mrflibble
author_rank: Super Contributor
timestamp: December 08, 2013, 07:02:56 pm
content: Quote from: danb35 on December 08, 2013, 05:15:52 pmThanks, the digitek is indeed a nice meter for the money. I should have mentioned that the budget per cheapo meter is < $10 shipped.

author: Lightages
author_rank: Unknown
timestamp: December 08, 2013, 07:34:12 pm
content: If you find a multimeter with a serial link included for <$10, I will buy one for you.

author: mrflibble
author_rank: Super Contributor
timestamp: December 08, 2013, 08:00:43 pm
content: Quote from: Lightages on December 08, 2013, 07:34:12 pmHeh, and one or two for yourself no doubt. But it's a deal.Please note that the meter itself is allowed to be medium crappy, as per the DT830 example.DT830 + PCB + MSP430G2203IPW28 + PC817C + handfull of passives < $10 at 10 pieces, not counting time spent (hobby and all that). But that's not nearly as convenient as just buying a couple of meters and getting on with other projects.

author: dr_p
author_rank: Frequent Contributor
timestamp: December 08, 2013, 09:06:36 pm
content: aren't you better off building a serial voltmeter from scratch?

author: mrflibble
author_rank: Super Contributor
timestamp: December 08, 2013, 09:14:51 pm
content: Possibly, but I am looking for a reasonably quick fix, not a new project.

author: linux-works
author_rank: Super Contributor
timestamp: December 23, 2013, 04:50:40 pm
content: vichy vc99 is one. here's a write-up I did a year or two ago:http://www.amb.org/forum/diy-hacking-multimeters-for-rs232-data-logging-output-t1210.html

author: mianchen
author_rank: Regular Contributor
timestamp: December 23, 2013, 07:54:15 pm
content: VC99 is more than $10sent from Mars

author: sachleen
author_rank: Contributor
timestamp: December 23, 2013, 08:35:15 pm
content: There was this instructableDMM Piggyback (add RS-232)a while ago which taps into a pin on the controller. Looks like the same/very similar meter, too.

author: linux-works
author_rank: Super Contributor
timestamp: December 23, 2013, 10:19:08 pm
content: yes, its more than $10. so what?I can't believe someone would want a data logger that is the price of a lunch. what good would it be, at such a low price point?the vc99 is junk but at least its usable junk.

author: tautech
author_rank: Super Contributor
timestamp: December 23, 2013, 11:28:05 pm
content: Had any thoughts of using an SMD opto internally and a small socket for the link out of the meter?A bit of sleeving and careful installation should make a safe permanent connection.Just plug in the Serial to USB, cable and go.

author: linux-works
author_rank: Super Contributor
timestamp: December 24, 2013, 12:38:44 am
content: what I had planned (but never did) was to make these send data over xbees to remote pc's that are also usb-connected to xbees. sort of a wireless data logger, on the cheap.

author: mrflibble
author_rank: Super Contributor
timestamp: December 24, 2013, 01:17:00 am
content: Quote from: sachleen on December 23, 2013, 08:35:15 pmHey, thanks for the link! That turned out to be very useful.

author: sachleen
author_rank: Contributor
timestamp: December 24, 2013, 02:16:23 am
content: Quote from: mrflibble on December 24, 2013, 01:17:00 amNo problem! Let us know what you end up doing and how it works out. I actually have a couple of these Cen-Tech meters laying around (get them for free from Harbor Freight every once in a while) and am considering doing this just for fun.

author: mrflibble
author_rank: Super Contributor
timestamp: December 24, 2013, 02:20:09 am
content: Quote from: linux-works on December 23, 2013, 10:19:08 pmWell, for some cases 3 1/2 digits is sufficient. And while a more accurate meter is always nice, it's usually also more expensive. Granted $30 isn't super much, but when multiplied by lets say 4 or 8 it becomes a nice chunk of cash. Sooo 4-8 times $10, yes. 4-8 times $30, no.For the money the VC99 looks okay. In that price bracket I think I would pay ~ $50 for a UT61E though. Better resolution and already has serial interface. If only, because I had the UT61E on the list already.The idea is to have one good meter (3478A), one decent meter (UT61E) and several cheapos (the < $10 one).

author: mrflibble
author_rank: Super Contributor
timestamp: December 24, 2013, 02:30:54 am
content: Quote from: sachleen on December 24, 2013, 02:16:23 amBased on your link I actually started looking for places to buy a few of those Cen-Tech meters. But it seems they are only afforable on the US market. I have checked a few webshops, but mostly ebay. The base price is already a bit high for a 2000 count DM and shipping from the US to Europa totally kills it.I had discarded the DT830 as option because Iassumed(silly me!) that there was a TC7106 in there. But after viewing a bunch of youtube vids of recent DT830 teardowns I noticed that the ADC blob and surrounding pads look very much like the Cen-Tech. So it's no guarantee, but definitely worth shot.

author: sachleen
author_rank: Contributor
timestamp: December 24, 2013, 02:41:32 am
content: Here's another discussion on the Cen Tech and there seem to be a couple of meters that look nearly the same but with different brands. The DT830 is mentioned.https://www.eevblog.com/forum/reviews/harbor-freight-cen-tech-90899-small-teardown/Best way to find out is to get one and take it apart! Worst-case, you can always decode the LCD.

author: sync
author_rank: Frequent Contributor
timestamp: December 24, 2013, 02:31:44 pm
content: Quote from: mrflibble on December 24, 2013, 02:20:09 amWhat's about a used bench multimeter with scanner card? If you are really patient you could get them low priced. I got a Keithley 199 with 8 channel scanner for 80€. Of course you probably have to deal with GPIB then. Or build your own scanner and use a RS232 capable DMM.

author: mrflibble
author_rank: Super Contributor
timestamp: December 24, 2013, 03:22:42 pm
content: Yes. Cheap. Patience.For some cases a scanner would do the trick, but for other cases (2 seperate setups with 4 DMMs each) the scanner solution would be spatially challenged.And if you know of any working Keithley 199's with scanner for 80 euro, I'll buy that.

author: mianchen
author_rank: Regular Contributor
timestamp: December 24, 2013, 06:11:19 pm
content: Quote from: linux-works on December 23, 2013, 10:19:08 pm$10 was the OP's requirement. Please read before patronizing.sent from Mars

author: tld
author_rank: Regular Contributor
timestamp: December 25, 2013, 01:28:30 am
content: I'm curious now. Would you mind explaining what you'd like to log?I get that you're not looking for a major project, but you could do a lot of logging with an msp430, for not much more work than it would be to decode the LCD.tld

author: mrflibble
author_rank: Super Contributor
timestamp: December 25, 2013, 02:10:58 am
content: Quote from: tld on December 25, 2013, 01:28:30 amI would mind it a little bit yes.Because on a board like this that tends to result in Alternate Solutions . Which sometimes is a good thing, but other times it just distracts from the fairly simple mission: Get bunch of cheapo DMM's with RS-232. Suffice to say that it is not one thing, it is a bunch of small projects for which the total compromise solution is to get said bunch of cheapo DMMs.QuoteThis is true. However with the off the shelf cheapo DMM you get a "free" project box with high contrast display, battery compartment, crappy-but-adequate test leads, and a dual slope integrating ADC which is better at rejecting noise than the ADC in an MSP430. Not bad for $4 in single units and $2 in bulk. Or $2 in singles if you live near a Harbor Freight.edit:fix typo

author: Unknown
author_rank: Unknown
timestamp: December 25, 2013, 02:41:22 pm
content: Quote from: mrflibble on December 24, 2013, 03:22:42 pmThat's a pretty standard price if you're patient. I've bought two for under $100 shipped and recently saw one sell for €100, all with scanner.