Power input block: 15V connector
15V comes in directly onto the main rail and ground, with no series protection diode. Correct-polarity connection matters here, since there's nothing to catch a reversed connection.
Regulated supply block: IC2 (78XX-series) + C4, C5, C6, C7
IC2 steps the 15V rail down to a regulated output that feeds the 555's VCC and reset pins, keeping the timer's supply separate from the higher-current switching rail. C7 (0.1µF) and C4 (100µF) bypass/bulk the regulator's input; C6 (0.1µF) and C5 (100µF) do the same on the output side. Note: the schematic uses a generic 78XX symbol with no specific voltage value set, so the exact regulated voltage isn't confirmable from the file alone — worth checking against your actual populated part.
Oscillator block: IC1 (NE555) + R4 + C3 + C2
This is a self-triggering relaxation oscillator: threshold and trigger are tied together, and that node charges/discharges through the trimmer R4 (10k) directly from the 555's own output, with C3 (10nF) as the timing cap. Discharge is unused. C2 (0.1µF) is the standard control-voltage bypass. R4 is your frequency-trim knob, meant to bring the 555's free-running rate into alignment with the LC tank's resonant frequency below.
Gate-drive block: R1 + R3
R1 (10R) is the gate series resistor from the 555's output, limiting instantaneous gate-charge current and damping ringing in the gate-drive loop. R3 (10k) pulls the gate to ground, keeping Q1 reliably off if the gate is ever left floating.
Resonant output block: Q1 + L1 (330µH) + C1 (0.1µF)
Q1's source is grounded, and its drain sits on a node shared by L1 and C1. L1's other end is wired directly to the 15V rail. When Q1 turns on, current builds through L1 from the rail; when Q1 turns off, that current can't stop instantly, so the drain voltage swings upward and the LC network (L1 together with C1 and the piezo's capacitance, which sit effectively in series from the drain's perspective) goes into its resonant transition — an approximately sinusoidal ring, with the exact shape depending on switching timing, inductor Q, piezo impedance, and how closely the 555's frequency tracks the loaded resonance. C1 couples that ringing drain node out to the PIZO connector.
Indicator block: R2 + LED1
R2 (10k) feeds LED1 from the regulated rail to ground — a simple "board is powered" indicator, unrelated to the oscillator or output stage.
How it comes together
The 555 free-runs at a rate set by R4 and C3, tuned close to the LC tank's resonance. Each cycle, Q1 switches, energy transfers into the tank, the tank rings near its natural frequency, and the direct connection to the 15V rail replenishes the energy the piezo dissipates as it vibrates. It's open-loop throughout — nothing about the piezo's or drain's actual waveform feeds back into the 555; the design's job is simply getting the oscillator frequency and the loaded resonance close enough together that the switching drives the tank efficiently. Since L1 is now 330µH (a real change from whatever value was there when this was last tuned), the resonant frequency has shifted, and the 555's rate via R4/C3 should be re-checked against the tank's new resonance rather than assumed to still be correct.
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you tube video link with all files :
https://www.youtube.com/watch?v=kNJp2BRtzR4
113Khz Water Atomizer Circuit + PCB
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