Lab 0.2 — Breadboard Continuity + Resistor Measurement
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Goal
Master the two things you will do on the bench more than anything else: wiring a solderless breadboard correctly and reading a resistor with the meter. You will use the Fluke 117’s continuity beeper to prove which breadboard holes are electrically joined (so you never again wonder “is that node actually connected?”), then use resistance mode to read color codes, verify tolerance, and confirm series/parallel combination formulas by measurement. Every analog and mixed-signal lab in this course is built on a breadboard, so an internalized mental map of its topology — and the reflex to beep out a node when a circuit misbehaves — is foundational debugging skill for firmware and hardware bring-up alike.
Recommended reading
- Lyons Ch. 1 — the “signals and systems” framing of what we’re building toward; a light read for context, not detail. → Lyons
- Kuo Ch. 1 — the real-time DSP system context (the analog front-end resistors and dividers we build here feed the converters later). → Kuo
- The Fluke 117 manual: the resistance, continuity, and diode-test section, and the auto-ranging behavior of the Ω function.
- PEI Ch. 3 — Basic Electronic Circuit Components: resistors, the color code, tolerance, and series/parallel combinations.
- Course 1 Weeks 1–3 (linear algebra) are not required here, but the parallel-resistor “reciprocal sum” is the same conductance-adds intuition you’ll reuse in every network analysis. → Course 1
Equipment & parts
- Fluke 117 DMM + test leads.
- One solderless breadboard from the kit (with an MB102 power-supply module fitted or not — it is unpowered for this whole lab).
- A handful of jumper wires.
- Resistors from the 480-piece kit: at least 100 Ω, 220 Ω, 330 Ω, 1 kΩ, and 10 kΩ, ¼ W. Grab two of one value (e.g. two 1 kΩ) for the series/parallel section.
Safety & don’t-break-it
- Never measure resistance or continuity on a powered board. The Ω/continuity function sources its own small test current and assumes the circuit is de-energized. A live node will give nonsense readings and can damage the meter’s Ω input. For this lab the breadboard is fully unpowered — the supply from Lab 0.1 stays off and disconnected. Make this a reflex: ohms and beeps only on dead circuits.
- Resistance readings drift if you touch both probe tips with your fingers — your body is a ~1 MΩ resistor in parallel. Hold resistor leads by one end, or lay the part on the bench and probe each lead.
- A resistor is non-polarized and rugged, so nothing here can be “blown” — this lab is about habits, not hazards. The one real mistake is leaving the meter in a current or voltage mode and expecting an ohms reading; confirm the dial is on Ω before you probe.
- Seat components fully. A lead that only touches the top lip of a breadboard hole reads as an intermittent open. Push each lead down until it seats in the spring clip.
Background
Breadboard topology. A standard breadboard is a grid of spring-clip holes with a fixed internal connection pattern you must know cold:
- Terminal strips (the main grid). The board is split by a center gap (the trough) running lengthwise. On each side of the gap, holes are joined in columns of five — a vertical run of 5 holes (labeled a–e on top, f–j on bottom) is one electrical node. The five holes in a column are shorted together; adjacent columns are not connected.
- The center gap. The trough down the middle breaks continuity between the top and bottom halves. Its width is sized for a DIP chip: you straddle the gap with the IC so pins on the left and right rows land in separate columns, and no two pins are accidentally shorted. This is why DIPs always mount across the trough.
- Power rails (the bus strips). The long lines marked + (red) and − (blue) down the outside edges are each one long horizontal node running the length of the board (some boards break the rail in the middle — beep it to check). Rails on opposite edges are independent; you jumper them to your supply.
Continuity. The Fluke’s continuity mode beeps when the resistance between the probes is below a threshold (typically ~\(25\text{–}30\ \Omega\)). It is a fast Boolean “are these two points the same node?” test — perfect for mapping the board and hunting shorts (unintended beeps) and opens (missing beeps).
Resistor color code. A 4-band resistor encodes value as (digit)(digit)(multiplier)(tolerance):
\[R = (10 \cdot d_1 + d_2)\times 10^{\,m}\ \Omega, \qquad \text{tolerance from the 4th band.}\]
Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. Tolerance band: gold ±5%, silver ±10%. So brown-black-red-gold = \(10\times10^2 = 1\text{ k}\Omega \pm 5\%\).
Series and parallel. Resistances in series add; in parallel their conductances add:
\[R_\text{series} = R_1 + R_2, \qquad R_\text{parallel} = \left(\frac{1}{R_1}+\frac{1}{R_2}\right)^{-1} = \frac{R_1 R_2}{R_1 + R_2}.\]
For two equal resistors \(R\): series \(=2R\), parallel \(=R/2\).
Procedure
Part A — Map the breadboard with the continuity beeper.
- Put the Fluke leads in COM (black) and VΩ (red). Turn the dial to continuity (the sound-wave / diode symbol; press the function button until the beeper icon shows). Touch the two probes together once to confirm it beeps.
- Prove a column is one node: insert a jumper into hole a1, and probe a1 and e1 (top of the same column). It should beep — the five holes are joined. Now probe a1 and a2 (adjacent column): no beep — separate nodes.
- Prove the center gap breaks the halves: probe a top-half column hole (e.g. e5) and the bottom-half hole directly across the trough (f5). No beep — the gap isolates top from bottom.
- Map the power rails: probe two holes far apart on the same + rail. It should beep (one long node). Probe a + rail hole and a − rail hole: no beep. If your board’s rail is split in the middle, you’ll find a spot where two same-color holes don’t beep — note where the break is and bridge it with a jumper if you need a continuous rail later.
- Sketch the board’s connectivity in your bench notebook from what you measured — not from memory.
Part B — Read resistors by color code, then verify with the meter.
- Turn the dial to Ω (resistance). The Fluke auto-ranges.
- Take each resistor (100 Ω, 220 Ω, 330 Ω, 1 kΩ, 10 kΩ). First read its color bands and write down the nominal value and tolerance. Then probe the two leads (part off the board, held by one lead only) and read the meter.
- For each, compute whether the measured value is inside the tolerance band, e.g. a \(1\text{ k}\Omega \pm5\%\) part is in-spec anywhere from 950 Ω to 1050 Ω.
Part C — Series and parallel, measured vs computed.
- Series: plug two 1 kΩ resistors into the breadboard end-to-end — resistor 1 spanning columns so one lead is in column 10 and the other in column 12; resistor 2 continuing from column 12 to column 14. Column 12 is now the shared node. Probe the two outer leads (col 10 and col 14): expect ≈ 2 kΩ.
- Parallel: move the two 1 kΩ resistors so both span the same pair of columns (both left leads in column 20, both right leads in column 22). Probe column 20 to column 22: expect ≈ 500 Ω.
- Repeat Part C with an unequal pair (e.g. 1 kΩ + 10 kΩ) and predict first: series \(=11\text{ k}\Omega\), parallel \(=\frac{1\cdot10}{1+10}\text{ k}\Omega \approx 909\ \Omega\).
Deliverable & expected results
A bench note (docs/lab-0-2.md) with: your hand-sketched breadboard connectivity map (columns / gap / rails, annotated with the beep results), the color-code-vs-measured table for the five single resistors, and the series/parallel table below.
| Quantity | Predicted | Measured |
|---|---|---|
| 100 Ω single | 100 Ω (±5%) | … |
| 1 kΩ single | 1 kΩ (±5%) | … |
| 10 kΩ single | 10 kΩ (±5%) | … |
| Two 1 kΩ in series | 2.00 kΩ | … |
| Two 1 kΩ in parallel | 500 Ω | … |
| 1 kΩ + 10 kΩ series | 11.0 kΩ | … |
| 1 kΩ ∥ 10 kΩ parallel | 909 Ω | … |
Analysis & reconciliation
Compute each combination by hand and compare to the meter. Expect discrepancies of a few percent, and account for their sources: each resistor’s own ±5% tolerance dominates (two nominally-equal 1 kΩ parts might be 990 Ω and 1015 Ω, so their series sum won’t be exactly 2.000 kΩ); the meter’s own lead resistance (a few tenths of an ohm) matters only for the smallest values — beep your leads shorted together and note the residual reading to subtract it from the 100 Ω measurement; and contact resistance at the breadboard spring clips adds a little series ohmage, which is exactly why continuity’s threshold is ~25 Ω rather than 0. If a series measurement is far off, beep out the shared node to confirm the two resistors are actually joined where you think they are.
Going further
- Find a deliberate short: jumper two adjacent columns together, then use continuity to locate the bridge as if debugging a real board — this is the exact workflow you’ll use when a powered circuit misbehaves later.
- Measure a potentiometer from the kit across its outer legs (fixed total) and from wiper to one end (varies as you turn it) to see a variable resistance.
- Preview the next lab: put the meter in capacitance mode and read a capacitor’s value, then in Lab 0.3 compare it against the LCR meter’s frequency-dependent reading.