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Breadboard Tie Point Explorer

Run the Breadboard Tie Point Explorer MicroSim fullscreen

About This MicroSim

A breadboard is already wired before you touch it. Under the white plastic are metal clips that tie certain holes together, and almost every first-night hardware failure comes from guessing that wiring wrong.

There are only two rules, and this sim makes both visible:

A tie column is five holes, not ten. Rows a-e of column 12 are one connection. Rows f-j of column 12 are a different connection. The grey channel down the middle is a wall, not a decoration -- it exists so a chip can straddle it with its two rows of legs on separate nets.

A power rail is one connection running the whole length of the board. The holes come in groups of five with a gap between groups, which makes them look like separate sections. They are not. Click any rail hole and watch the entire strip light up.

One detail worth pointing out while the Show all rails toggle is on: there are four rails, not two. The top pair and the bottom pair are electrically separate. A circuit powered from the top rails gets nothing from the bottom rails until somebody adds a jumper wire between them -- which is exactly the wire the other circuits in this chapter run at column 19.

How to Use

  • Click any hole to highlight its whole connected group in amber.
  • Click a hole in rows a-e, then the hole directly below it in rows f-j. Same column number, two different groups. That is the center channel.
  • Turn on Show all rails to see all four power rails at once in blue.
  • Clear selection removes the amber highlight.

Lesson Plan

Bloom level: Remember (L1) -- identify

Learning objective: Given a labeled breadboard diagram, the learner identifies which holes are electrically connected to a clicked hole.

Before the sim (5 min). Hand out real breadboards if you have them and ask the group to guess which holes are connected. Collect two or three competing guesses on the whiteboard without saying which is right.

With the sim (10 min). Test each guess by clicking. The productive surprise is the center channel: nearly everyone assumes a column runs the full height of the board.

After the sim (10 min). Give each student a component with two legs and ask where the legs must go so the component is not shorted out. Both legs in the same column is the mistake to catch -- the sim makes it obvious why nothing happens when you do that.

Check for understanding. Point at hole d7 and ask: "Name every other hole connected to this one." The answer is a7, b7, c7, and e7 -- five holes, stopping at the channel. A student who includes f7 has not yet got it.

Embedding This MicroSim

Paste this into any page of the book, adjusting the relative path to docs/sims/ for the page's depth:

<iframe src="../../sims/breadboard-tie-point-explorer/main.html" width="100%" height="642" scrolling="no"></iframe>

Specification

The full specification below is extracted from Chapter 16: Physical Computing and Electrical Safety Basics.

Type: microsim
**sim-id:** breadboard-tie-point-explorer<br/>
**Library:** p5.js<br/>
**Status:** Specified<br/>
**Template:** https://github.com/dmccreary/stem-robots/tree/main/docs/sims/breadboard-layout-explorer

Purpose: Let a mentor click any hole on a drawn breadboard and instantly see every other hole it is electrically connected to.

Bloom Taxonomy: Remember (L1)
Bloom Taxonomy Verb: identify

Learning objective: Given a labeled breadboard diagram, the learner identifies which holes are electrically connected to a clicked hole.

Visual elements: A full-size breadboard drawing with two power rails (top and bottom) and the central five-hole columns, rendered at real proportions

Interactive controls: Click any hole to highlight, in one color, every hole tied to it; a "Show all rails" toggle that highlights both power rails at once in a second color

Default parameters: No hole selected on load; clicking any hole triggers the highlight

Behavior: On click, redraw the board with the clicked hole's full connected group highlighted and a text label reading either "Power rail" or "Column {n}"

Implementation notes: p5.js grid rendered from a 2D array encoding each hole's connection-group id; click detection maps mouse coordinates to the nearest hole

References