This project is a custom-built electronics training kit designed to teach beginners how series and parallel circuits work using light bulbs, resistors, capacitors, a switch, and a variable power supply.

It includes:

1. 12V plug-in power adapter
2. Step-up converter (boosts 12V → up to ~20V)
3. Variable output with LED voltage display
4. Replaceable light bulb sockets
5. Built-in resistor bank
6. Built-in capacitor bank
7. Potentiometer section
8. ON/OFF toggle switch
9. Banana-plug terminals for easy wiring
10. Complete trainer layout for performing dozens of circuit activities

This kit is ideal for students, tech-voc classes, STEM labs, and hands-on demonstration of Ohm’s Law.

Main Components

1. 1 × 12V DC wall adapter
2. 1 × DC–DC step-up converter (12V → adjustable 20V max)
3. 1 × Digital voltmeter LED display
4. 1 × Variable power supply knob (potentiometer)
5. 3–4 × Mini light bulbs with sockets (2.5 v)
6. Banana plug terminals (red/black)
7. 10 × resistors mounted to binding posts
8. 10 × capacitors mounted to binding posts
9. 1 × ON/OFF toggle switch
10. Jumper wires with banana plugs
11. Wooden or acrylic base board

Tools

1. Drill
2. Soldering iron
3. Hot glue
4. Screwdriver
5. Wire stripper

Your trainer is built on a compact wooden enclosure with a printed front-panel template that guides all drilling and mounting.

The enclosure size is:

1. Width: 230 mm
2. Height: 195 mm
3. Depth: 50 mm

This gives plenty of internal space for wiring and the step-up power section.

1. Print the Front Panel Template and Front Panel Graphic

1. Print your layout at 100% scale so it matches the actual 195 × 230 mm dimension.
2. The template already shows:
3. Bulb socket positions
4. Resistor and capacitor banks
5. Switch and potentiometer locations
6. Power supply terminals
7. LED voltage display cutout

2. Glue the Template to the Wooden Lid (Wood Glue Only)

Since your build uses wood glue, here’s the correct process:

1. Brush or spread a thin, even layer of wood glue on the top surface of the wooden lid.
2. Place the printed template on top, aligning the edges with the board.
3. Smooth the paper using your hands or a cloth to remove any trapped air.
4. Let it dry completely before drilling to prevent tearing.

✔ Wood glue dries rigid and strong

✔ No need for spray adhesive

✔ Paper stays permanently attached once cured

3. Mark the Drill Points

1. Use a small nail or center punch to mark every hole printed on the template.
2. This keeps drill bits centered and prevents slipping.

4. Drill All Component Holes Through the 50 mm Deep Enclosure

Use the correct drill bit sizes:

1. 3–5 mm: screw holes, small terminals
2. 6–8 mm: banana jacks
3. 10–12 mm: switch and potentiometer
4. Slot / rectangular cut: LED display (drill multiple small holes then file open)

The 50 mm height gives you safe clearance for:

1. banana plug lugs
2. step-up converter module
3. potentiometer body
4. internal wiring
5. switch mechanism
6. DC input connector

Nothing inside will touch the bottom of the box.

5. Optional: Seal the Paper (If You Want Extra Durability)

This is optional, but helpful if students will use it often:

1. Apply a very thin coat of clear varnish, or
2. Cover with a clear plastic sheet / contact paper

But this is NOT required since wood glue already clamps the paper solidly.

Use the template as your drilling guide:

1. 3–5 mm holes
2. Resistor posts
3. Capacitor posts
4. 6–8 mm holes
5. Banana binding posts
6. 10–12 mm holes
7. Switch
8. Potentiometer
9. Rectangular opening
10. LED voltmeter (use drill + file technique)

Dry-fit components before mounting.

STEP 3: MOUNT THE COMPONENTS

A. Light Bulb Section

Mount all lamp holders and secure them to the panel.

B. Resistor Bank (Updated and Standardized)

This trainer uses ONLY 5.1 Ω, 2 W resistors for all resistor positions.

1. Install banana binding posts according to the template.
2. Solder one 5.1 Ω, 2 W resistor between each pair of posts.
3. Label the area “5.1 Ω, 2 W Resistor Bank.”

C. Capacitor Bank

Install all capacitor binding posts.

D. Power Supply Section

Install the:

1. DC barrel jack
2. LED voltmeter
3. Potentiometer
4. Toggle switch
5. Output terminals

follow the circuit diagram above

1. Power Input → Step-Up Converter

1. Connect the 12 V adapter jack to the input side of the converter.
2. Mount the module inside the enclosure.

2. Step-Up Converter → Potentiometer → Output

1. Wire the adjustable output as designed.
2. Connect LED voltmeter in parallel with output terminals.
3. Place the toggle switch as a master ON/OFF before the converter.

3. Component Banks

1. Wire each bulb holder to its respective posts.
2. Solder each 5 Ω resistor to its post pair.
3. Wire capacitor posts to the capacitor components.

Use hot glue or cable ties to organize internal wiring.

4. Build the Resistor Bank

Each resistor seen by the student is a finished two-terminal block.

Internally, you create the target value using combinations.

Internal configurations:

R1 — 2.5 Ω

1. Built using two equal-value resistors in parallel
2. Connect the parallel network between its pair of binding posts

R2 — 5 Ω

1. Single resistor
2. Connect directly between the posts

R3 — 7.5 Ω

1. Two resistors in series
2. Run the full series string between the two terminals

R4 — 10 Ω

1. Three resistors in series
2. Wire end-to-end, then to the posts

R5 — 1.6 Ω

1. Three resistors in parallel
2. Tie all left leads together → left binding post
3. Tie all right leads together → right binding post

After building each network:

1. Apply heat-shrink
2. Screw down the post nuts
3. Label each pair:

Before handing the trainer to students:

1. Use a multimeter to confirm resistance values at the banana terminals:
2. 2.5 Ω
3. 5 Ω
4. 7.5 Ω
5. 10 Ω
6. 1.6 Ω
7. Power on the 12V supply:
8. Check voltmeter reading
9. Test lamp lighting
10. Test fuse continuity

Everything should be stable before classroom use.

Activity 1: Series Circuit

1. Connect 5 Ω → 7.5 Ω → 12V
2. Measure total resistance and current

Activity 2: Parallel Circuits

1. Connect 2.5 Ω ∥ 5 Ω
2. Measure current sharing

Activity 3: Lamp Brightness

1. Lamp in series with 10 Ω
2. Observe dimming
3. Measure voltage drop

Activity 4: Mixed Circuits

1. Build RLC-style (lamp + resistor parallel/series) structures

This DC Resistance Trainer provides a safe, durable, and highly flexible tool for teaching the fundamentals of electricity. By using banana-plug wiring and modular resistor terminals, students can freely build and test their own circuits without risk of damaging equipment. The fixed internal resistor combinations ensure precise values, while the lamp load, voltmeter, and fuse add realistic behavior—allowing students to observe voltage drop, current changes, brightness variation, and the effects of series and parallel connections.

Whether used for classroom demonstrations, hands-on lab sessions, or practical exams, this trainer helps learners build confidence through real experimentation. With clear labeling, simple operation, and strong visual feedback, it becomes an essential part of any introductory electronics or electrical technology course.

Thank you for following this build!

If you’d like enhancements such as current meters, more resistor options, digital voltmeters, or a full printable front-panel layout, feel free to explore additional upgrades or ask for more guides. Happy building, and enjoy your new training module!