Supply voltage: 4.5V-5.5V DC;
Laser harp principle:
The laser harp is a harp without strings. Instead, a bright beam of light is used. The user simply dials the beam and plays a melody like a string. The photoresistor and the single-chip STC89C52 are composed of two parts. When the beam emitted by the laser tube is blocked, the corresponding photoresistor senses and changes the resistance value. The system composed of the eight photoresistors generates high and low potential changes, and the high-low potential change of the photoresistor is read by the single-chip microcomputer to complete the input of the operation command. The MCU controls the data to transmit data through the serial port according to the instruction information, and assigns the value of the p0^2 port of the docking speaker and the p1 port of the connected water lamp to generate a corresponding reaction.
When there is laser irradiation, the microcontroller reads the voltage of the photoresistor, at which time it is low. When there is no laser irradiation, the microcontroller reads the voltage of the photoresistor, then it is high. Thus, when the light of the laser light is blocked, the effect of the switch can be generated in the circuit.
The frequency of the human ear can be heard from 20Hz to 20kHz, and the harp note frequency should also be in this range. Just, different notes have their own fixed frequency. The above o can be generated by the 16-bit timer that comes with the 52 MCU. For example, the standard sound la of the harp is 440 Hz. It can be seen from the calculation that its half period is 1136 μs. In this way, a square wave of 440 Hz can be generated by hopping the pin level in a half cycle. After the electroacoustic conversion element (horn), the standard tone la can be generated, and other notes are also generated.
1. There are 7 strings in total, and the buzzer emits the corresponding level when cutting the strings.
2. When the string is cut, the corresponding LED of the string lights up, a total of 7 LEDs
3. Play the two songs stored by pressing the button
4. Switch between high and low sounds
1 x Laser Harp Kit