Understanding Circuit Schematic
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Great question. The DC-to-AC conversion happens at the MOSFET switching stage. Here’s the exact path and “where” the waveform turns into AC, tied to parts and nets in your schematic.
What creates the AC
- The PWM controller U1 oscillates at a frequency set by R1 and C7, producing two alternating drive signals on its outputs (Nets 7 and 11).
- Those two signals go into the gate driver U2, which strengthens them and sends them through gate resistors R5 and R6 to the MOSFET gates Q1 and Q2. Zeners D7 and D5 clamp VGS to keep the gates within safe limits.
- As Q1 and Q2 turn on alternately, their drain nodes (Net 8 and Net 9) swing between near-12 V and near-0 V in opposite phases.
- That pair of opposite-phase switch nodes creates an alternating voltage across the primary winding. This is the exact “DC to high-frequency AC” conversion point: the AC exists across the primary because the ends are being yanked up/down alternately by the two drains (Net 8 and Net 9).
Then AC goes back to DC
- The secondary’s alternating voltage is rectified by the fast diodes D1, D2, D3, and D4.
- The pulsating DC is smoothed by the output inductor L1 and capacitor C10, yielding a steady high-voltage DC at the output.
Probe/mental model (if you visualize or measure)
- U1 outputs (Nets 7, 11): clean logic-like PWM.
- MOSFET gates (after R5/R6): strong PWM drive, clamped by D7/D5 so VGS stays safe.
- MOSFET drains (Net 8, Net 9): large, opposite-phase square-like waveforms. The alternating voltage across these two nodes is the high-frequency “AC”.
- Rectifier inputs (D1–D4): high-frequency pulses.
- Output after L1/C10: smoothed DC.
If you want, I can mark these exact nodes in your schematic (gates, drains, rectifier inputs) and label “here is where it becomes AC,” then “here it becomes DC again.”
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Label AC nodes
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D7
D5
12V
R12
Resistance
10k Ω
R9
Resistance
1M Ω
12V
R6
Resistance
500 Ω
12V
Vref
R10
Resistance
33k Ω
12V
R5
Resistance
500 Ω
U1P16
R11
Resistance
4.7k Ω
U1P1
Vref
R1
Resistance
33k Ω
12V
D2
J1
C4
Capacitance
100u F
12VGND
C6
Capacitance
120u F
U2
F1
C7
Capacitance
1n F
C8
Capacitance
10u F
Q2
D1
D3
Q1
D4
C5
Capacitance
10n F
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- Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portaljharwinbarrozo43.0M
- Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #powerjharwinbarrozo11.4M
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- A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibraryjharwinbarrozo1.5M
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GROUP 1 FINAL PCB
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| Distributor | Qty 1 | |
|---|---|---|
| Arrow | $10.71–$12.46 | |
| Digi-Key | $10.82–$11.64 | |
| LCSC | $16.94–$18.28 | |
| Mouser | $20.95 | |
| TME | $11.72 | |
| Verical | $7.09–$11.43 | |
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