Interactive Circuit Block Visualizer, Cascading Fault Simulator & Sandbox
Probe power, regulator, MCU, clock & driver chains with a dual-trace oscilloscope (ΔV/ΔT/f cursors), DMM/Logic Probe overlay, unpowered Ω-to-GND mode, multi-fault cascades & drag-and-drop Sandbox
How to Use This Tool
This interactive visualizer models a complete power, regulation, clock, processor, and output driver chain. Use it to trace animated color-coded signal flow, compare healthy vs. faulted waveforms with dual-trace cursors, inspect DMM/Logic Probe and unpowered resistance readings, simulate multi-fault cascades, or build custom architectures in Sandbox Mode.
1. Probe & Measure (Dual-Trace Scope, DMM/Logic Probe & Unpowered Ω): Click any Test Point (TP1–TP5) to connect the virtual oscilloscope. Toggle Dual-Trace Baseline vs. Fault and drag the on-screen V1/V2 (ΔV) and T1/T2 (ΔT & Frequency) cursors. Switch instrument modes to overlay live DMM DC voltages + Logic Probe states (HIGH / LOW / PULSE / HI-Z) or perform an Unpowered Resistance / Impedance Test (Ω-to-GND & diode drop) right on the schematic.
2. Multi-Fault Injection, Cascading Failures & Live Degradation: Enable Fault Simulation to inject individual faults, combine multiple simultaneous faults, or launch a Cascading Failure Chain (e.g., Shorted Filter Cap → Overcurrent → V-REG Thermal Shutdown → MCU Brownout Loop). Use the live parameter sliders to vary Input Voltage (VIN), Load Current (ILOAD), Capacitor ESR / Ripple, Thermal Drift (°C), and Cold Solder Parasitic Resistance (Ω) in real time.
3. Ecosystem Cross-Links, Sandbox Builder & Worksheet Export: Click any circuit block to open direct links to the IC Pinout Quick-Finder and Hardware Diagnostic Flowcharts, plus verified replacement parts from the Substitution Guide and capacitor kits from the Recap Reference. Switch to Sandbox Mode to drag-and-drop custom block chains, or click Export Diagnostic Worksheet for a complete PDF or Markdown bench checklist.
Signal & Current Flow Schematic
Verified Component Replacements & Recap BOM Reference
Showing verified drop-in replacements (from the Logic & RAM Substitution Guide) and low-ESR electrolytic capacitor specifications (from the Recap & Repair Reference) for the active circuit stage and fault state.
Verified IC & Semiconductor Substitutions Full Substitution Guide →
Replace hot linear 7805 with Recom R-78E5.0-1.0 or Traco TSR 1-2450 switching buck module (94% efficiency, no heatsink required). For AMS1117-3.3, use AP2112K-3.3 or MCP1700-3302E for lower dropout.
Use 74HCT04 / 74HCT245 (TTL-compatible VIH ≥ 2.0V). Avoid plain 74HC on NMOS/TTL buses (requires VIH ≥ 3.5V). Never swap 74LS244 into a 74LS245 socket.
3.3V/5V MCU GPIOs require an L-suffix logic-level MOSFET (IRLZ44N, AO3400A, or IRL540N, VGS(th) < 2.0V). Standard IRFZ44N requires 10V gate drive and will overheat in linear mode.
Verified Capacitor Recap BOM & Board Kits All 44 Board Recap BOMs →
| Ref | Spec | Low-ESR Replacement | Rail / Function |
|---|---|---|---|
C1 |
100 µF 25V | Nichicon UPW1E101MPD (105°C Low-ESR) | 12V Bulk Input Filter (TP1) |
C3 |
10 µF 25V | Panasonic EEU-FR1E100 (105°C Radial) | V-REG Input Decoupling |
C4 |
22 µF 16V | Nichicon UHE1C220MDD / Murata MLCC | 3.3V/5V Regulated Output (TP2) |
C11/C12 |
18 pF 50V | Murata C0G/NP0 ±5% Ceramic | 16 MHz XTAL Load Caps (TP3) |
Block Inspector & Ecosystem Links
Step-Down / Voltage Regulator
Output: 3.3V @ 500mA (or 5V @ 1A). Dropout: <0.5V. Ripple: <20mV pk-pk. Line regulation: ±2%. Load regulation: ±3%.
AMS1117-3.3 or LM7805 (U1), 10µF/16V input cap (C3), 22µF/10V output cap (C4), 100nF ceramic decoupling caps (C5, C6).
Multimeter (DC Voltage): Measure regulator output (pin 3). Expected: 3.300V ±100mV. Oscilloscope: Check output ripple <20mV.
Powered Logic State: HIGH (3.30V DC, <20mVpp). Unpowered Resistance to GND: ~2.2 kΩ (Diode drop: 0.58V). Reading <10Ω indicates shorted C4 or MCU rail.
Diagnostic Worksheet (PDF / Markdown)
Live summary of healthy baseline vs. current faulted measurements, cursor deltas, unpowered Ω-to-GND specs, and bench steps.
Fault Finding by Signal Chain, Dual-Trace Scope & Unpowered Impedance
Nearly every embedded or retro mainboard, however complex it looks, reduces to the same functional chain: power comes in through fuse and polarity protection, a linear or switching regulator turns it into clean logic rails, those rails feed a CPU or microcontroller, a crystal oscillator provides the system clock, and an output buffer or MOSFET stage drives the load. Diagnosing in that exact order matters because a fault at any upstream stage produces convincing symptoms in every block downstream of it.
1. Unpowered Ohms-to-Ground Before Applying Power
Before switching on a suspect board or replacing a blown fuse, switch the visualizer to Unpowered Ω-to-GND Test Mode. Measuring resistance to ground and diode voltage drops across TP1 (bulk input) and TP2 (regulated rail) catches shorted tantalum capacitors (<2 Ω) and crowbarred protection diodes before they can overheat a linear regulator or damage vintage custom silicon.
2. DMM / Logic Probe Overlay vs. Dual-Trace Oscilloscope Cursors
A digital multimeter averages out high-frequency events, which is why a leaky filter capacitor with 650 mVpp of 100 Hz ripple often reads as an acceptable 3.08 V DC on a DMM while causing random MCU brownout resets and clock jitter. Toggle the DMM + Logic Probe Overlay to verify steady DC levels and digital pin states (HIGH, LOW, PULSE, or floating HI-Z), then use the Dual-Trace Oscilloscope with AC Coupling and draggable ΔV, ΔT, and Frequency (1/ΔT) cursors to compare the healthy baseline waveform (CH1) directly against the degraded or faulted signal (CH2).
3. Multi-Fault Injection, Cascading Failures & Component Degradation
Real-world bench repairs rarely involve a single textbook open circuit. Use the Multi-Fault Matrix and Cascading Failure Chains to observe how a primary defect triggers secondary failures — such as a shorted output tantalum capacitor overloading an LDO into thermal foldback shutdown, or an open flyback diode allowing inductive kickback spikes to punch through a MOSFET and blow the input fuse. Vary the live sliders for Input Voltage (VIN), Load Current Demand (ILOAD), Capacitor ESR (Ω), Thermal Drift (°C), and Cold Solder Parasitic Resistance (Ω) to see how marginal components fail under load.
4. Custom Sandbox Chains, Ecosystem Cross-Links & Diagnostic Worksheets
Switch to Sandbox Mode to drag-and-drop custom hardware block topologies — including Commodore 64 PLA/DRAM chains, ZX Spectrum triple-rail (-5V / +12V / +5V) DC-DC converters, and Amiga audio/video stages. Every block links directly to the IC Pinout Quick-Finder, Hardware Diagnostic Flowcharts, Logic & RAM Substitution Guide, and Verified Recap BOMs. Click Export Diagnostic Worksheet at any time to print a formatted PDF bench sheet or download a Markdown report.
For related signal analysis and sizing calculations, open the Universal Signal & Trace Visualizer (8-Ch Logic Analyzer), the Ohm’s Law & Power Calculator, and the 555 Timer & LED Calculator.
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