Transistor

Build the real thing

Giant 3D print + real ones on a breadboard

Put a real transistor on a breadboard with a battery, an LED, two resistors and a button, so a tiny current into the base switches a bigger one through the LED. A giant printed model shows the three legs up close; that print file comes once we've test-printed it.

Cost

$ · Under $25

Time

One session

Screens

No screen needed

Build it in bricks

115 pieces · 16 steps · Medium · parts checked September 24, 2026

Booklet: Activities Pass members now · free for email subscribers from October 15, 2026

• Already a member? Sign in →
• Preview (free: cover, parts, step 1) →
• Other ways to get it (for grown-ups) →

Where to buy the parts

The parts lists are free. Booklet: Activities Pass members now · free for email subscribers from October 15, 2026.

Do this on a computer: you save a file here, then upload it to the store.

1. BrickLink: Wanted List (XML)

   Open the file in a text editor and copy all of it. On BrickLink, choose Want → Upload → BrickLink XML format, paste, verify the items, then add them to a Wanted List.

2. LEGO Pick a Brick: Parts upload (CSV)

   A US & Canada beta, and some parts may not be stocked. On Pick a Brick, choose Upload list, add this file, then Upload.

3. BrickOwl: BrickLink XML

   On BrickOwl, choose Wishlist → Import → Import BrickLink XML and upload this file.

4. Rebrickable: BrickLink XML

   Make a Part List on Rebrickable, choose Import/Delete Parts, then upload this file on the BrickLink XML tab.

Full parts list with part numbers (CSV)

Parts data: Rebrickable, checked September 24, 2026.