Measurement and instruments lesson plan
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.
Objectives and materials
By the end, students can
- What the digits mean, and what the meter does to the circuit.
- Bandwidth, the x10 probe and a trigger you write yourself.
- Frequency, duty and the bytes on a bus.
- An error budget for a battery gauge, then calibrate it.
Materials for the whole unit
- 74HC595 shift register
- Arduino Uno R3
- Bench power supply
- Capacitor x 3
- Frequency counter
- Full-size breadboard
- Function generator x 2
- I/O expander, PCF8574
- Logic analyzer, four channels
- Multimeter x 2
- NE555 timer
- Oscilloscope
- Potentiometer
- Resistor x 2
Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too.
The meter, honestly
What the digits mean, and what the meter does to the circuit.
| Lesson | Time | What students do |
|---|---|---|
| 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. | 45 min |
|
| 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. | 45 min |
|
Materials
- Arduino Uno R3
- Full-size breadboard
- Multimeter x 2
- Potentiometer
- Resistor x 2
Check for understanding
Each student finishes "Meter loading" on their own, without opening the hints. The simulator checks 6 of its 6 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Quick check".
The scope
Bandwidth, the x10 probe and a trigger you write yourself.
| Lesson | Time | What students do |
|---|---|---|
| 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. | 55 min |
|
| 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. | 55 min |
|
Materials
- Arduino Uno R3
- Capacitor x 3
- Full-size breadboard
- Function generator x 2
- Multimeter x 2
- Oscilloscope
- Resistor x 2
Check for understanding
Each student finishes "Triggering" on their own, without opening the hints. The simulator checks 7 of its 7 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Quick check".
Counting and decoding
Frequency, duty and the bytes on a bus.
| Lesson | Time | What students do |
|---|---|---|
| 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. | 45 min |
|
| 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. | 55 min |
|
Materials
- 74HC595 shift register
- Arduino Uno R3
- Capacitor
- Frequency counter
- Full-size breadboard
- I/O expander, PCF8574
- Logic analyzer, four channels
- Multimeter
- NE555 timer
- Resistor x 2
Check for understanding
Each student finishes "Logic analyzers" on their own, without opening the hints. The simulator checks 7 of its 7 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Quick check".
Boss
An error budget for a battery gauge, then calibrate it.
| Lesson | Time | What students do |
|---|---|---|
| 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. | 60 min |
|
Materials
- Arduino Uno R3
- Bench power supply
- Full-size breadboard
- Multimeter
- Resistor x 2
Check for understanding
Each student finishes "Boss: an error budget" on their own, without opening the hints. The simulator checks 8 of its 8 steps as they go.
Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Write the budget".
Teach this unit as a class
Start a class from this course and its 7 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you.
The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way.