Schematic Recreation Review
What was created
A best-effort Flux schematic was created from the uploaded GZ-TU-REV2_sch.png image. It includes:
- USB Micro-B input connector SH1.
- MCP73831 charger U1.
- Two NE555D timer blocks U2 and U3.
- Two assumed MMBT3904 NPN transistor switches Q1 and Q2.
- Diodes D1 and D2, LED1, switches S1 and S2.
- R1-R12 as 2 kΩ generic resistors.
- C1-C6 as 10 µF generic capacitors.
Named nets created
- RAW: USB VBUS input to U1 VDD and input capacitor.
- VCC: charger VBAT/system rail feeding both 555 timers and bias parts.
- BATTERYCUTOFF: inferred switch/transistor control net around Q1.
- TRIP: inferred signal from U2 output toward U3 trigger and Q2 base network.
- OUTPUT: inferred U3/Q2/indicator output net.
- GND: common return.
Best-effort assumptions
- U2 and U3 were implemented as NE555D SOIC-8 timers because the image only clearly indicates 555-style pin functions.
- Q1 and Q2 were implemented as MMBT3904 NPN transistors because the markings were unreadable.
- D1 and D2 were implemented as 1N4148W switching diodes because exact diode types and orientations were unreadable.
- S1 and S2 were implemented as momentary tactile switches because switch style/action was unreadable.
- USB data pins D+ and D- plus ID were retained as labeled single-pin nets because the image did not show a clear downstream data connection.
Items requiring user verification
- Confirm all resistor values read as 2 kΩ.
- Confirm all capacitor values read as 10 µF and whether any are polarized.
- Confirm Q1/Q2 transistor type, polarity, and pinout.
- Confirm D1/D2 diode type and orientation.
- Confirm U2/U3 exact timer variant and package.
- Confirm S1/S2 switch type and normally-open/normally-closed behavior.
- Confirm whether USB D+, D-, and ID should be no-connects or wired elsewhere.
- Confirm the exact point-to-point topology around BATTERYCUTOFF, TRIP, and OUTPUT from the original CAD if available.