From PhET's Circuit Construction Kit to logic gates
Circuit Construction Kit: DC is one of the free simulations from PhET Interactive Simulations at the University of Colorado. In its own words: "Experiment with an electronics kit! Build circuits with batteries, resistors, ideal and non-Ohmic light bulbs, fuses, and switches. Determine if everyday objects are conductors or insulators, and take measurements with an ammeter and voltmeter. View the circuit as a schematic diagram, or switch to a lifelike view." Its learning goals include explaining basic electricity relationships in series and parallel circuits and building circuits from schematic drawings, and a companion, Circuit Construction Kit: AC, adds AC sources, capacitors and inductors. The kit stops where digital logic starts: at the switch. digiwleea picks up there, and it is a different kind of simulator.
What the kit does well
It makes electricity visible: you see current flow, measure voltage and current with lifelike meters, find out which everyday objects conduct, and switch between a schematic and a realistic view. For a first look at series and parallel circuits it is hard to beat, and PhET describes its sims as free, interactive and research-based. (digiwleea is an independent project, not affiliated with PhET or the University of Colorado.)
From switches to logic gates
Put two switches in series with a bulb and it lights only when both are closed: that is AND. Put them in parallel and either one will do: OR. Now swap the hand-worked switches for transistors, switches worked by a voltage, and one circuit's output can flip the next circuit's switches. That is how logic gates are built, and from them adders, memory and whole CPUs. digiwleea simulates exactly that layer: each wire is 0, 1 or floating rather than a voltage and a current, so it does not measure amps or ohms and complements the kit rather than replacing it.
| PhET Circuit Construction Kit | digiwleea | |
|---|---|---|
| Simulates | Current, voltage and resistance | Logic levels: 0, 1 and floating |
| Parts | Batteries, resistors, bulbs, fuses, switches, meters | Transistors, gates, flip-flops, memory |
| Goal | Electricity: series and parallel circuits | Digital logic, up to a working CPU |
| Runs in | The browser | The browser |
| Price | Free | Free lab and Act I; Premium for the full course |
Where to go after the kit
- Switches as logic. The lesson on logic as switches: series is AND, parallel is OR.
- A switch worked by a voltage. The NMOS switch and the MOSFET simulator.
- The first gates. The CMOS inverter (NOT from two transistors) and the CMOS NAND, then the logic gate simulator and the AND and OR truth tables.
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
Can you build logic gates in PhET's Circuit Construction Kit?
You can show the idea with its switches: two switches in series act as AND and two in parallel as OR, with a bulb as the output. The kit has no transistors or logic gates, though; for those you need a logic simulator such as digiwleea.
Is PhET Circuit Construction Kit free?
Yes. PhET describes its simulations as free, interactive, research-based science and mathematics simulations, and they run in the browser.
What is the difference between Circuit Construction Kit: DC and AC?
The DC kit has batteries, resistors, light bulbs, fuses and switches. The AC kit adds AC voltage sources, capacitors and inductors.
What should I learn after series and parallel circuits?
If you are heading toward computers, the transistor as a switch and then logic gates: they are series and parallel switch circuits where the switches are worked by voltages instead of fingers.