Looking for cheapo multimeter like DT830, but with serial link

[mrflibble]

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. 

[danb35]

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 also http://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

[mrflibble]

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 also http://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

Thanks, the digitek is indeed a nice meter for the money. I should have mentioned that the budget per cheapo meter is < $10 shipped.

[Lightages]

If you find a multimeter with a serial link included for <$10, I will buy one for you.

[mrflibble]

If you find a multimeter with a serial link included for <$10, I will buy one for you.

Heh, 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.

[dr_p]

aren't you better off building a serial voltmeter from scratch? 

[mrflibble]

Possibly, but I am looking for a reasonably quick fix, not a new project.

[linux-works]

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

[mianchen]

VC99 is more than $10

sent from Mars

[sachleen]

There was this instructable DMM Piggyback (add RS-232) a while ago which taps into a pin on the controller. Looks like the same/very similar meter, too.

[linux-works]

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.

[tautech]

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. 

[linux-works]

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.

[mrflibble]

There was this instructable DMM Piggyback (add RS-232) a while ago which taps into a pin on the controller. Looks like the same/very similar meter, too.

Hey, thanks for the link! That turned out to be very useful.

[sachleen]

Hey, thanks for the link! That turned out to be very useful.

No 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.

[mrflibble]

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?

Well, 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).

[mrflibble]

No 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.

Based 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 I assumed (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.

[sachleen]

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.

[sync]

Well, 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.

What'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.

[mrflibble]

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.

[mianchen]

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.

$10 was the OP's requirement. Please read before patronizing.

sent from Mars

[tld]

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

[mrflibble]

I'm curious now. Would you mind explaining what you'd like to log?

I would mind it a little bit yes. Because on a board like this that tends to result in Alternate Solutions [tm]. 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.

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.

This 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

[alm]

And if you know of any working Keithley 199's with scanner for 80 euro, I'll buy that.

That'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.