Block Diagram Builder
⚠️ Beta testing
This tool is new and still being tested. The questions and answers have been checked against the marking instructions, but if something looks wrong, or a block will not drop where you expect, please tell Mr Stewart — do not assume your own answer is at fault. Use it alongside past papers rather than instead of them.
New and still being tested — if something looks wrong, tell Mr Stewart rather than assuming your own answer is at fault.
Read the problem, then drag blocks from the bank into the input, process and output sections. There are always more blocks than you need. You can also tap a block and then tap a slot, or use Tab and Enter.
Scroll the diagram sideways to see all three sections.
Why this is the answer
SQA marking guidance for this style of question
Six marks are available in the exam:
- 1 mark — selecting both input devices
- 1 mark — selecting the correct gates
- 1 mark — selecting both output devices
- 1 mark — correctly linking the inputs to the gates
- 1 mark — correctly linking the gates to the outputs
- 1 mark — correctly identifying the three sections of the system
Arrows are not required on the connections, but every selected element must be shown as part of a block diagram — a list or a table scores no more than 5. Do not draw logic gate symbols: write the gate name in a box.
This builder gives you the links and the three sections, so it marks the three selection marks. In the exam you draw the boxes, links and section labels yourself.
Logic gate truth tables
Sources & credits
Sources & credits: Questions 1–6 are past-paper and specimen questions © Qualifications Scotland (SQA), reproduced for educational use in support of SQA qualifications on a non-commercial basis; located using the National 5 Practical Electronics Past Papers compilation by J Keegan (November 2025), used with permission. Questions 7–12 are original practice problems written for this site (© R Stewart, 2026). Full site credits are on the credits page.