How it works
See inside everyday devices on interactive diagrams: follow the energy, check what you'd measure at each point, and find a hidden fault by measuring.
230 V mains input: from the socket to the bridge
This is every device's first stop. What is the voltage at the socket like, how does the bridge rectifier turn it one way, and why does the capacitor make 310 V? Follow it step by step on the diagram, then change the capacitor and load in the simulation below.
Step 2🔒 repair packHow does a phone charger work?
A box the size of your palm turns 230 V into a safe 5 V for your phone. Tap the blocks and follow the energy; then try "Find the fault" to track down real faults by measuring.
Step 3🔒 repair packHow does a laptop adapter work?
Pick a state at the top right to see what changes inside the adapter while the laptop charges, with no load, and with the laptop off. Then use "Find the fault" to track down the 5 faults repairers see most by measuring.
Step 4🔒 repair packHow does an LED bulb work?
Inside the bulb, dozens of LEDs are wired in series and a small IC keeps their current steady. Tap the blocks, watch the LED current; then use "Find the fault" to work out why it went dark.
Step 5🔒 repair packHow does an LED TV power board work?
In standby only a small part of the board runs. Switch to "On" at the top right and watch which sections wake up when you press the remote. Then use "Find the fault" to track down the faults repairers see every day.
Step 6🔒 repair packHow does a PC power supply (ATX) work?
Even with the PC off, a small part of the supply runs: 5VSB. Switch to "On" at the top right and watch which sections wake up when you press the power button. Then use "Find the fault" to track down the commonest faults by measuring.
Step 7🔒 repair packHow does a UPS (uninterruptible power supply) work?
The simplest form of the hybrid inverter: one 12 V battery, a few MOSFETs and a big transformer. Switch the state at the top (grid on, power cut, low grid) and follow the energy. Then use 'Find the fault' to track down the commonest faults by measuring.
Step 8🔒 repair packHow does a voltage regulator work?
The box that feeds the home's appliances close to 220 V even when the grid is low or high. Inside there's one big autotransformer, relays that pick its taps and a processor that decides. Change the grid voltage at the top and watch which tap comes into play.
Step 9🔒 repair packHow does a hybrid (off-grid) inverter work?
Tommatech, Growatt, Must or Axpert: the brands differ but the insides are largely the same. Switch the operating state at the top (solar, night, grid) and watch how the energy path changes. Then use 'Find the fault' to track down the commonest faults by measuring.
Step 10🔒 repair packMotor drivers: from small to big
Driving a motor means giving it the right current at the right moment. At its simplest one transistor sets only the speed; each step adds an idea: direction, steps, electronic commutation, making a new 3-phase supply, and finally closing the position loop with an encoder. Go through the steps in order and play each simulation.
Step 11🔒 repair packHow does a soft starter work?
Put 400 V straight onto a stopped motor and it draws 6–8 times its rated current. A soft starter raises the voltage slowly with thyristors and closes the bypass contactor when the ramp ends. Switch the state at the top and follow the energy, then compare the three methods' peak currents in the simulation.
Step 12🔒 repair packHow does a frequency inverter (VFD) work?
An induction motor's speed depends on frequency. A VFD turns the mains into DC, stores it in capacitors, then uses IGBTs and SPWM to make a new supply for the motor. Switch states, tap blocks to measure, then try the fault-finding mode.
Step 13🔒 repair packHow does an inverter welding machine work?
Old welders carried a 20 kg iron transformer; an inverter welder does the same job with a palm-sized ferrite transformer at 50 kHz. Compare idle, welding and stuck-rod states on the diagram, strike the arc in the simulation to see how the control holds the current constant, then identify the parts on the board drawing.
Step 14🔒 repair packHow does a PLC (programmable logic controller) work?
A PLC is the relay-and-wire control circuit turned into software. Switch the state at the top (RUN, motor stopped, STOP) and follow the signal from the button to the contactor. In the simulator, turn on 'Slow scan' to watch the PLC run its program line by line, then use 'Find the fault' to track down typical field faults by measuring.