Multimeter notes: Difference between revisions

Revision as of 15:36, 24 June 2024

⚠ This is for beginners and very much by a beginner / hobbyist

It's intended to get an intuitive overview for hobbyist needs. It may get you started, but to be able to do anything remotely clever, follow a proper course or read a good book.

Some basics and reference: Volts, amps, energy, power · batteries · resistors · transistors · fuses · diodes · capacitors · inductors and transformers · ground

Slightly less basic: amplifier notes · varistors · changing voltage · baluns · frequency generation · Transmission lines · skin effect

And some more applied stuff:

IO: Input and output pins · wired local IO · wired local-ish IO · · Various wireless · 802.11 (WiFi) · cell phone

Sensors: General sensor notes, voltage and current sensing · Knobs and dials · Pressure sensing · Temperature sensing · humidity sensing · Light sensing · Movement sensing · Capacitive sensing · Touch screen notes

Actuators: General actuator notes, circuit protection · Motors and servos · Solenoids

Noise stuff: Stray signals and noise · sound-related noise names · electronic non-coupled noise names · electronic coupled noise · ground loop · strategies to avoid coupled noise · Sampling, reproduction, and transmission distortions

Audio and video notes: See avnotes

Platform specific

Arduino and AVR notes · (Ethernet)

Microcontroller and computer platforms ··· ESP series notes · STM32 series notes

Less sorted: Ground · device voltage and impedance (+ audio-specific) · electricity and humans · Common terms, useful basics, soldering · landline phones · pulse modulation · signal reflection · Project boxes · resource metering · SDR · PLL · vacuum tubes · Multimeter notes Unsorted stuff

Some stuff I've messed with: Avrusb500v2 · GPS · Hilo GPRS · JY-MCU · DMX · Thermal printer ·

Accuracy

Multimeter resistance figure slowly increasing

Multimeters and capacitors

Multimeters and inductors

Safety

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-Assume that accuracy in general, for a not-particularly-fancy model are often better than 1% on DC,
+If you're working in industry and calibrating things, this is important.
-particularly on voltage and current.
+Most things hobbyists do, though?
-Some functions are inherently a little harder to do than others, e.g. capacitance, very high resistance.
+Say, when I care to check whether the Vcc line is at 5, 3.3V, or 0V,
+I don't care whether it's three digits or four-digit accurate.
-Really cheap no-name multimeters may be be 2 or 3% or 4% in some functions.
+If I want to check a battery, I'm guessing what 1.2, 1.5, 3.4V, 12.1V or 13.7V mean about what's happening,
+then I'm not bothered unless it's more than a few percent off.
-Expensive Brand multimeters tend to be better than 1% on most functions.
-AC is its own topic, because
+Assume that cheap multimeters are not any better than 1% on DC voltage and current.
+AC voltage and current is its own topic, because
 cheaper variants ''assume'' a sinusoidal waveform in their mains measurement, and
-only more expensive ones sample faster and do rms calculations.
+only more expensive ones actually sample that any better.
+Also, some functions are inherently a little harder to do than others, e.g.
+* very high resistance.
+* lower capacitance
+* very low resistance (in that the test cables may be too thin and at some point you're measuring ''them'')
+Really cheap no-name multimeters may be be 2 or 3 or 4% ''in some functions''.
+Expensive Brand multimeters tend to be better than 1% on most functions,
+but even people
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