Vol. IV — Electronics · Trainer
A closed loop, Ohm's law, series and parallel, then capacitors, RC time, Kirchhoff, Thévenin, Norton, Superposition, diode I-V, mesh/nodal equations, BJT common-emitter bias, and an N-channel MOSFET as a voltage valve. Change the knobs. The numbers and the drawing update together. Maker is the same page with parts you place yourself.
Current only moves when the path is complete. Open the switch, then close it. Watch the loop light up.
I = 0 while the switch is open.
Lessons is the original trainer: eighteen fixed drawings and knobs. Maker is a grid where you place parts, snap wires, and solve. Nothing is uploaded. A saved circuit stays in this browser until you clear it.
| Knobs | Voltage, resistance, and the extra knob for the lesson. The readout and the drawing move together. |
|---|---|
| Switch | Open stops the current. Close completes the loop. The switch on the drawing does the same thing. |
| Topology chips | Series, parallel, LED, diode, capacitor, RC, divider, Thévenin, Norton, superposition, mesh, BJT, FET. Next lesson unlocks when that lesson’s goal is met. |
| Place | A palette button drops that part on the grid. Drag it. It snaps to the grid. |
|---|---|
| Wire | Wire, then tap two leads. The route is a right-angle polyline between those leads. Tap a wire and Delete to lift it. |
| Select | Drag a part to move it. Drag empty canvas to pan. Shift-drag, or Multi, boxes several parts. Ctrl or Cmd A selects all. |
| Rotate, flip | Rotate turns the selection 90 degrees. Flip mirrors it. R and F do the same. Leads stay on the wires. |
| Copy, paste | Copy and Paste, or Ctrl or Cmd C and V. The copy lands two grid steps down and right, wires included. |
| Undo | Undo and Redo. Ctrl or Cmd Z, and Shift with that for redo. |
| Zoom | Zoom in, Zoom out, the wheel, or a two-finger pinch. Drag empty canvas to pan. |
| Probe, meter | Probe shows one node. Meter shows the difference of two taps. Volts labels every other node. The side panel shows the selected part. |
| DC point | Modified nodal analysis. Capacitors open, inductors short, AC sources at 0 V. Diodes, LEDs, and the NPN use Shockley junctions. |
| Run | Transient from rest, backward Euler. The scope follows the probe, else the selected part, else the capacitor or resistor. Space starts and stops when the canvas is focused. Stop returns to the DC point. |
| Examples | Voltage divider, RC charge, LED and resistor, half-wave rectifier, RL current, op-amp ×3, 555 astable, NAND. |
| Hints | No ground. A floating island. A source past 5 A (a short). An LED past 20 mA. |
| Save | Save JSON writes a text file. Load reads that file back. The same text is kept in this browser. Share link puts it on the address bar as ?maker=1&c=. |
| Sources | DC, AC sine, and a current source. Each voltage source has 0.05 Ω inside so a dead short is a large current instead of a broken matrix. AC is 0 V at the DC point. |
|---|---|
| LED and diode | Shockley. The silicon diode is near 0.7 V at a milliamp. The LED is near 2 V at 20 mA. The lesson LED is still a fixed 2 V drop. |
| NPN | Forward transport plus a reverse junction, so it can saturate. Beta is the knob. A sketch, not a datasheet. |
| Op-amp | Finite gain, default 100000, with rails. Non-inverting gain is about 1 + Rf/Rg. |
| Gates and 555 | Ideal logic with a 100 Ω output. The 555 is a latch: set below 1/3 of Vcc, reset above 2/3, discharge to ground while the output is low. Run it. The DC point is not the oscillation. |