Tube PSU with emergency current knee protection at 260mA. If a short circuit or overcurrent conditions are detected at the output, the regulator output is quickly pulled to 0V and the delayed rise up is also reset.
Most right switch simulates a condition just on the threshold of the circuit.
The one on the left is overcurrent condition above around 260mA.
The one on the bottom resets the current limit.
Response time of current limiter - less than 50us for the output to disable and around 120ms to discharge all capacitors at current limit threshold. Output capacitor will discharge quicker with heavier loads.
