Component values and references in PCB Design - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Component Reference Designators

In a PCB design, what does the reference designator R5 typically represent?

A The fifth resistor component on the board

B The fifth relay component on the board

C The fifth resistor-capacitor network

D The fifth rotary switch

💡 Hint

Reference designators usually start with a letter indicating the component type.

In PCB design, 'R' stands for resistor. 'R5' means the resistor labeled number 5.

❓ dax_lod_result

intermediate

Calculating Total Resistance from Component Values

You have a table of components with their reference designators and resistance values in ohms. Which DAX measure correctly calculates the total resistance of all resistors?

PCB Design

Components = DATATABLE("Ref", STRING, "Value", INTEGER, { {"R1", 100}, {"C1", 10}, {"R2", 200}, {"L1", 5} })

A TotalResistance = CALCULATE(SUM(Components[Value]), Components[Ref] = "R")

B TotalResistance = SUMX(FILTER(Components, Components[Ref] = "R"), Components[Value])

C TotalResistance = SUM(Components[Value])

D TotalResistance = CALCULATE(SUM(Components[Value]), FILTER(Components, LEFT(Components[Ref],1) = "R"))

💡 Hint

Use FILTER to select only resistors by checking the first letter of the reference.

Option D filters components where the reference starts with 'R' and sums their values correctly.

❓ visualization

advanced

Best Visualization for Component Value Distribution

You want to show the distribution of component values by type (Resistors, Capacitors, Inductors) on a dashboard. Which visualization is best?

A A stacked bar chart showing total values per component type

B A pie chart showing percentage of each component type by count

C A scatter plot with component value on X-axis and reference number on Y-axis

D A line chart showing component values over time

💡 Hint

Think about comparing totals across categories clearly.

A stacked bar chart clearly shows total values per component type, making it easy to compare.

❓ data_modeling

advanced

Modeling Component References and Values

You have two tables: Components with reference designators and Values with component values. How should you model the relationship to analyze component values by reference?

A Create a many-to-many relationship between Components and Values on Ref

B Create a one-to-many relationship from Components[Ref] to Values[Ref]

C Create a one-to-one relationship from Values[Ref] to Components[Ref]

D Do not create any relationship; use LOOKUPVALUE in measures

💡 Hint

One component can have one value, but values table may have multiple entries.

A one-to-many relationship from Components to Values on Ref allows aggregation of values per component.

🔧 Formula Fix

expert

Debugging Incorrect Component Value Aggregation

A DAX measure to sum resistor values is returning zero. The measure is:
TotalResistors = CALCULATE(SUM(Components[Value]), Components[Ref] = "R")
What is the cause of the problem?

A Components[Value] column contains text, not numbers

B SUM cannot be used inside CALCULATE

C The filter condition Components[Ref] = "R" is incorrect because Ref contains full designators like 'R1', not just 'R'

D CALCULATE requires an explicit FILTER function to work

💡 Hint

Check how the filter condition matches the data format.

The filter checks for exact match 'R' but references are like 'R1', so no rows match and sum is zero.

Practice

1.

What does a component reference on a PCB typically represent?

For example, R1 or C2.

easy

A. The electrical value of the component

B. The size of the component

C. The manufacturer of the component

D. A unique label identifying the component's position

Solution

1. Step 1: Understand component reference purpose

   Component references like R1 or C2 uniquely identify each part on the PCB for assembly and troubleshooting.

2. Step 2: Differentiate from component value

   Component values describe electrical properties (like resistance), not the label.

3. Final Answer:

   A unique label identifying the component's position -> Option D

4. Quick Check:

   Reference = Unique label [OK]

Hint: References label parts uniquely, not their values [OK]

Common Mistakes:

• Confusing reference with component value
• Thinking reference shows size or manufacturer
• Assuming reference is a measurement

2.

Which of the following is the correct way to write a resistor reference on a PCB schematic?

?

easy

A. R10

B. Res10

C. RX10

D. R-10

Solution

1. Step 1: Recall standard reference format

   Resistor references start with 'R' followed by a number, e.g., R10.

2. Step 2: Identify incorrect formats

   Options like 'Res10', 'RX10', or 'R-10' are not standard and may cause confusion.

3. Final Answer:

   R10 -> Option A

4. Quick Check:

   Resistor reference = R + number [OK]

Hint: Resistor references start with 'R' plus number [OK]

Common Mistakes:

• Adding extra letters after 'R'
• Using dashes or special characters
• Using non-standard prefixes

3.

Given the following component list on a PCB:

R1 = 10kΩ
C1 = 100nF
R2 = 1kΩ
C2 = 10nF

What is the total resistance if R1 and R2 are connected in series?

medium

A. 11kΩ

B. 9kΩ

C. 10kΩ

D. 1kΩ

Solution

1. Step 1: Identify resistors and their values

   R1 is 10kΩ and R2 is 1kΩ.

2. Step 2: Calculate series resistance

   In series, resistances add: 10kΩ + 1kΩ = 11kΩ.

3. Final Answer:

   11kΩ -> Option A

4. Quick Check:

   Series resistance = sum = 11kΩ [OK]

Hint: Add resistances directly in series [OK]

Common Mistakes:

• Multiplying resistances instead of adding
• Confusing series with parallel formulas
• Ignoring units (kΩ vs Ω)

4.

In a PCB design file, the component reference R1 is accidentally duplicated for two different resistors. What is the likely problem?

medium

A. The PCB will ignore one resistor

B. The PCB assembly may place wrong parts or cause confusion

C. The resistor values will automatically merge

D. The reference duplication has no effect

Solution

1. Step 1: Understand reference uniqueness

   Each component reference must be unique to avoid confusion during assembly.

2. Step 2: Identify consequences of duplication

   Duplicated references can cause wrong parts to be placed or errors in documentation.

3. Final Answer:

   The PCB assembly may place wrong parts or cause confusion -> Option B

4. Quick Check:

   Unique references prevent assembly errors [OK]

Hint: Each reference must be unique to avoid errors [OK]

Common Mistakes:

• Assuming values merge automatically
• Thinking duplication is harmless
• Believing PCB ignores duplicates silently

5.

You have a PCB with components labeled R1, R2, and C1. You want to create a dictionary in Python mapping references to their values:

{'R1': '10kΩ', 'R2': '1kΩ', 'C1': '100nF'}

Which code snippet correctly creates this dictionary using dictionary comprehension from two lists refs = ['R1', 'R2', 'C1'] and vals = ['10kΩ', '1kΩ', '100nF']?

hard

A. dict_comp = {refs[i], vals[i] for i in range(len(refs))}

B. dict_comp = {refs: vals for i in range(len(refs))}

C. dict_comp = {refs[i]: vals[i] for i in range(len(refs))}

D. dict_comp = dict(zip(vals, refs))

Solution

1. Step 1: Understand dictionary comprehension syntax

   Dictionary comprehension uses {key: value for ...} format, matching keys and values by index.

2. Step 2: Analyze options

   dict_comp = {refs[i]: vals[i] for i in range(len(refs))} correctly pairs refs[i] with vals[i]. dict_comp = {refs: vals for i in range(len(refs))} uses wrong syntax. dict_comp = {refs[i], vals[i] for i in range(len(refs))} uses comma instead of colon. dict_comp = dict(zip(vals, refs)) reverses keys and values.

3. Final Answer:

   dict_comp = {refs[i]: vals[i] for i in range(len(refs))} -> Option C

4. Quick Check:

   Correct dict comprehension syntax [OK]

Hint: Use {refs[i]: vals[i] for i in range(len(refs))} [OK]

Common Mistakes:

• Using comma instead of colon in comprehension
• Swapping keys and values in zip
• Incorrect comprehension syntax