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How can I fix this LED dimmer circuit?

schematic

simulate this circuit – Schematic created using CircuitLab

The circuit reverse-engineered above is a LED dimmer which is driven by 555 timer in astable mode which then drives an op-amp to provide current for the gate of the MOSFET. The circuit dims quite well but it has an issue, when you power it up for a brief moment the LED strip receives non-PWM voltage what results in full brightness and dimming according to the 10K pot position after a while. I was thinking in order to fix this I could remove the 7805 regulator and just replace it with buck converter which powers the PWM circuitry constantly, but I’m asking if there’s maybe more elegant solution here.

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