This article shows an ultrasonic lighting system:
You can see my circuit working in this video:
I created this circuit after reading those articles:
Step 1: Design the Circuit
I drawn the circuit in the old PSpice simulation software to reduce drawing and simulation time.
The Rv potentiometer controls the brightness of the bright LED. The LEDs that I used in my circuit might need no more than 5 mA current. A typical LEDs consumes a current of 10 mA and have potential voltage of 2 V across its terminals. High currents might burn the LEDs or reduce the LED lifetime.
Although microphone circuits are always biased, most ultrasonic circuits do not bias the ultrasonic sensor. In my circuit the DC current across the sensor is very small.
The Ri1 resistor is needed because the potential voltage across the ultrasonic sensor could be very small due to low resistance/impedance. The Ri2 resistor is not needed. I connected this resistor to change the circuit characteristic. The LEDs turn OFF when the ultrasonic signal is applied. You can connect the circuit shown in this link: (https://www.instructables.com/Transistor-Sensor-Amplifier) that is almost similar to my circuit.
All other information on circuit design is included in the Instructables links above.
The Instructables links above included RC (resistor capacitor ) power suplpy filters. you might need those filters if your circuit is oscillating.
Step 2: Simulations
Simulations show that my design is correct:
Step 3: Make the Circuit
You do not need to use the high power resistors that I used. I used 1 Watt resistors. You can use 1/4 Watt resistors. However, you got to admit that the circuit appears more professional with bigger resistors.