Laser harp’s strings is replaced by laser beam. You can play the laser beam as a string. Each beam has a different pitch. It’s very creative for you to DIY.
2. Principle of laser harp:
The user only needs to move the beam as if the string is moved, and a melody can be played. The laser harp is composed of two parts: a photosensitive resistor and a single chip microcomputer STC89C52. When the beam emitted by a laser tube is blocked, the corresponding photosensitive resistance is induced and the resistance changes are generated. The system of eight photosensitive resistors produces the change of high and low potential, and reads the high and low potential changes of the photosensitive resistance by the single chip computer, and completes the input of the operation instruction. The MCU controls data based on command information to transmit data through serial port, which is assigned to p0^2 port of loudspeaker and P1 port of water lamp to generate corresponding response.
When the laser is irradiated, the MCU reads the voltage of the photosensitive resistance, and it is low level at this time. When there is no laser irradiation, the MCU reads the voltage of the photosensitive resistance, then it is high level. In this way, when the light of the laser is shielded, the effect of the switch can be produced in the circuit.
The sound frequency of the human ear can be heard from 20Hz to 20kHz, and the frequency of the harp notes should also be in this range. It’s just that different notes have their own fixed frequency. The above audio can be generated by a 16 bit timer with a 52 single chip microcomputer. For example, the standard sound of the harp is La 440Hz. It can be seen from the calculation that the half cycle of it is 1136 Mu s. In this way, the square wave of 440Hz can be generated as long as the pin level is jumped in the half cycle. After the electrical conversion element (horn), the standard sound La can be produced, and the other notes are also produced.
1>.There are a total of 7 strings. When the string is cut, the buzzer sends out the corresponding sound level.
2>. When the string is cut, the LED of the string is lit up. There are a total of 7 LED.
3>. Play two pieces of music stored by buttons.
4>. Switch middle and high bass.