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Need a solid 3-4 channel DMM

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--- Quote from: AlfBaz on July 12, 2013, 04:15:35 am ---With the budget you've got you should end up with a nice solution.

I scored a HP3457A with a 44491 relay card for $275.
Whilst I haven't measured the time between channels at NPLC of 1 I can sample 4 channels (DCV) in under half a second. Makes a hell of a racket with the relays chattering but it does the job.

I'm a complete noob at labview but just now I'm using the relay card to check resistance drift of a trim pot compared to a fixed resistor and ambient temperature over time. I'm using a thermistor to measure temperature in 2 wire mode, converting it to temperature, then switching to 4 wire mode to measure the pot and resistor and plotting them on 3 separate XY graphs... Seems to be working a treat.

--- End quote ---
I was going to suggest the same thing.  The HP cards can be setup to read quite a few channels quite quickly.  Certainly worth a look. 

Unless you need very fast sampling, I would use either a DMM with built-in scanner (the Keithley 2000/2001 is the only current model that comes to mind, the already mentioned HP 3457A or Keithley 199 would be good options on the used market. Another alternative would be dedicated switching units like the HP 3488a. Used these tend to go for cheap since they're fairly useless outside ATE and similar applications. In all cases make sure you get the correct relay cards. These are usually optional and might come in several types. For example one for voltage/resistance, another for thermocouples, another for four-wire resistance, another for RF.

A DMM with > 1 actual channel (as in ADC) is going to be very rare outside data acquisition boards, and not really necessary unless you need sampling rate in the kS/s.


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