Electronics > Projects, Designs, and Technical Stuff
Community Bench Meter
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Bloch:
An onboard ADC will also lock the project to a single cpu.

The more modular the better.


Front end
adc
cpu
IO (to PC)
Display
Neb:
I don't see a need for a 31-bit adc since they are so expensive.  I think a 24-bit adc would be more than enough and the saved money can be spent on better input circuitry.  The real culprit will be getting the noise floor down and keeping it calibrated.  Ideally it would not need calibration, the references should be accurate and not drift.  If i try to calibrate it with a store bought DMM with 1% accuracy, i can't expect the device to produce better than 1% accuracy and the extra counts/adc bits are wasted.
firewalker:
Is this project dead?
Bored@Work:

--- Quote from: firewalker on December 27, 2010, 06:53:07 pm ---Is this project dead?

--- End quote ---
It was dead right from the beginning. Because

a) It is difficult. Despite the wet dreams of some, a good meter can't be done with just cobbing together a cheap ADC with a cheap MCU.

b) Because of a) it requires a good amount of work.

c) Most people discussing here were after getting it without any own effort, in the hope all they had to do was to add to the wishlist. This behavior is not compatible with b).

d) Most people discussing were just after getting something cheap. This won't happen. One can't beat the price of cheap multimeters, and one can't bet the price of expensive multimeters. The cheap ones are, well, just too cheap. The expensive ones require expensive parts and expensive equipment, e.g. to adjust them.

e) There was and is no forceful project leader. Someone skilled enough and with enough time on his or her hands  to push the project, to make decisions, to attract contributors, to guide contributors towards the common goal (heck, a common goal wasn't even defined), and keep contributors working for the project, even if their opinions are overruled.

f) No one is or was willing to fund the effort. See d) and e).

Realistically, it never had a chance of taking off.

If you want a community project, fix a) ... f), and probably some more issues I forgot to mention. If you want an good chance of having a DIY meter, forget about the community project, do it completely on your own, and once done brag about it. The leechers at HackADay will welcome you with open arms and make you their hero (for a day).
NiHaoMike:
It might not be worth the effort to build a high accuracy meter or an extra cheap meter, but there are some niche applications where it makes sense. Such as a meter that automatically calculates average and peak power. Or a datalogger that records voltages to a SD card at a sample rate of a few Hz or kHz. In any case, we'll make the assumption that the accuracy needed is comparable to or less than that of the under $20 meters and that the builder already owns a meter (and calibration reference) much more accurate than the one being built.

One extremely high accuracy measurement that is relatively easy to make is time/frequency. Put a GPS in your homemade frequency counter and you'll very likely have more accuracy than you'll ever need.
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