One of the regulated power supply overload indication circuits

An overload indicator is installed on the regulated power supply to measure the working condition of the regulated power supply for easy monitoring.
The circuit is shown in the figure. When normal, the indicator light H is off. When overload occurs, the output voltage decreases, the voltage regulator VS is cut off
, the transistor VT2 is cut off, VTi is turned on, and H lights up.
    The current limiting resistor Ri can be calculated as follows:
    R. Once the solid cloud ÷ falls (n)
U in the formula. , - regulator input voltage, V;
UH, I}i - are the rated voltage and     current the indicator light H, V, A respectively.