why i hate digital multimeters

how am i supposed to tell how to make this smart-drive washingmachine motor into a generator if the multi-meter thing jumps around like that? they only read the current/voltage/resistance every second or so & it is shear chance as to when you get a reading as to what the reading will be which is really annoying when you have a fluctuating or intermitant current. why can you not buy the old analouge multi-meters anymore? if the maximum output was supposed to be 400v~AC then why does this read 1800 at some point? am i doing something wrong? if it was that high then why do sparks not jump across the wires when the machines are on spin cycle?

Category:

Science & Technology

Tags:

• multi
• meter
• smart
• drive
• washing
• machine
• motor

[TehMG]

Since the output from your generator is a complex waveform, an oscilloscope would prove useful.

As for DMMs, a quality 'true RMS' multimeter such as a Fluke 187 should be way better than that meter you got. Cheap meters don't work worth a damn if what you are trying to measure is not pure DC or pure sinusoidal AC.

[slainwolf180]

Thankyou, if i ever set out to make something from that motor i shall have to remember to get better equipment

[highdeserthater]

screw digital up the ass. we live in an analog world. our world is corrupted with over engineered piles of shit. lol

[slainwolf180]

very true

[reuven1967]

For this you need a digital oscilloscope to properly record the waveform exactly as it is. Otherwise you need a continuous rotation of the machine to generate a stable waveform because the DMM you are using is reading instantaneous values at its own rate which is slow. That's why you see isolated samples only, which are meaningless. This DMM is cheap and probably measure a stable sinusoidal signal only. Your signal is actually more complex than that. A digital oscilloscope would be the best.

[ConnorXV]

Tried making an analogue one? All it is is a deflection needle in a box I'm sure it's a good simple project

[criscros7]

That seems to be a very cheap DMM. This makes overshoot (too high reading before it settles on the true value) more likely. Although half decent DMMs update 3 to 4 times a second and usually don't overshoot (much), a standard DMM isn't the right tool for following a quick changing signal. You can still buy analog MMs, but those are affected to varying degrees by the damping of the needle. A graphing/oscilloscope DMM would be the best choice. Expect to pay a lot more than for this cheapo, though.

[22Muddy]

have you put it on the right setting?

[TheNuclearWatermelon]

i REALLY hate when instead of giving the reading, they just say OL

[pixuma]

well these things do put out ALOT of electricity

[cyberteque]

Ok, my 2 cents worth!

That is the cheapest Chinese DMM money can buy!

Get a Fluke or at least spend another $100!

For what you are doing a CRO would be way better!

You can still buy analogue meters Jaycar still have 1 in there catalogue and I think Altronics still do as well.

Other than that, BUILD ONE!!

That way you can have all the features you want.

There have been a lot of designs in EA, Silicon Chip, ETI over the years.