Meter loading
Two 1 megohm resistors should halve 5 V. The meter says otherwise, because the meter is a 10 megohm resistor in the circuit. Predict the error, prove it, and learn when to stop worrying about it.
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Measurement and instruments
How far to trust a reading: resolution and accuracy, meter loading, bandwidth and the x10 probe, triggering, counters, bus decoding, and an error budget for a real gauge.
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What you will build
3 projects, built step by step
7 lessons in 4 chapters, about 6 hours on a simulated Arduino Uno R3. Free, in your browser, every step checked by the simulator.
Triggering
Why a scope trace stands still: a level and a slope. Set them on the scope, then write a trigger in code (slope, level and auto mode) and watch it behave exactly like the front panel.
Open it in the simulatorLogic analyzers
One analyzer, two buses: decode SPI into a shift register, then move the probes and decode I2C into an expander, including the NACK of a chip that is not there.
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Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
The meter, honestly
What the digits mean, and what the meter does to the circuit.
- Open200 XP
Accuracy and resolution
A bench meter and an Uno read the same knob. Counts, digits and the 4.88 mV step a 10-bit converter cannot see inside, and why "how fine" and "how right" are different questions.
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Meter loading
Two 1 megohm resistors should halve 5 V. The meter says otherwise, because the meter is a 10 megohm resistor in the circuit. Predict the error, prove it, and learn when to stop worrying about it.
0 of 6 steps
Chapter 2
The scope
Bandwidth, the x10 probe and a trigger you write yourself.
- Locked249 XP
Probes and bandwidth
Every instrument input is a low-pass filter. Find the corner of one with two AC meters, then build a x10 probe by hand and compensate it the way you tune a real one on the bench.
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- ProjectLocked462 XP
Triggering
Why a scope trace stands still: a level and a slope. Set them on the scope, then write a trigger in code (slope, level and auto mode) and watch it behave exactly like the front panel.
0 of 7 steps
Chapter 3
Counting and decoding
Frequency, duty and the bytes on a bus.
- Locked236 XP
Frequency counters
Count a 555 two ways, with a frequency counter and with a meter. Gate time and the last digit, duty cycle, and predicting a new frequency from the parts before you measure it.
0 of 6 steps
- ProjectLocked498 XP
Logic analyzers
One analyzer, two buses: decode SPI into a shift register, then move the probes and decode I2C into an expander, including the NACK of a chip that is not there.
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Chapter 4
Boss
An error budget for a battery gauge, then calibrate it.
- Locked262 XP
Boss: an error budget
A battery gauge reads 11.961 V on a 12.000 V supply. Find every millivolt: meter loading, resolution, resistor tolerance and the reference, then calibrate it and write the budget.
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Syllabus
Every lesson in the course
All 7 lessons, in order, each with what it covers. Any of them opens in the editor right away.
The meter, honestly
- Accuracy and resolutionA bench meter and an Uno read the same knob. Counts, digits and the 4.88 mV step a 10-bit converter cannot see inside, and why "how fine" and "how right" are different questions.
- Meter loadingTwo 1 megohm resistors should halve 5 V. The meter says otherwise, because the meter is a 10 megohm resistor in the circuit. Predict the error, prove it, and learn when to stop worrying about it.
The scope
- Probes and bandwidthEvery instrument input is a low-pass filter. Find the corner of one with two AC meters, then build a x10 probe by hand and compensate it the way you tune a real one on the bench.
- TriggeringWhy a scope trace stands still: a level and a slope. Set them on the scope, then write a trigger in code (slope, level and auto mode) and watch it behave exactly like the front panel.
Counting and decoding
- Frequency countersCount a 555 two ways, with a frequency counter and with a meter. Gate time and the last digit, duty cycle, and predicting a new frequency from the parts before you measure it.
- Logic analyzersOne analyzer, two buses: decode SPI into a shift register, then move the probes and decode I2C into an expander, including the NACK of a chip that is not there.
Boss
- Boss: an error budgetA battery gauge reads 11.961 V on a 12.000 V supply. Find every millivolt: meter loading, resolution, resistor tolerance and the reference, then calibrate it and write the budget.
Kits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Find your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
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About Measurement and instruments
Is Measurement and instruments free?
Yes. All 7 lessons of Measurement and instruments are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need a real Arduino Uno R3?
No. Every lesson runs on a simulated Arduino Uno R3 with its parts on the canvas, and the simulator checks each step as you go. When you want to build it for real, the same wiring and code work on a real board.
How long does Measurement and instruments take?
About 6 hours: 7 lessons in 4 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: Meter loading, Triggering and Logic analyzers.
Where do I start?
With "Accuracy and resolution", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.