This photoelectric piano has a total of 7 strings, and the buzzer emits the corresponding sound level when cutting the strings. Equipped with LED lights, the corresponding LED lights up when cutting the strings, totaling 7 LEDs. Optoelectronic pianos do not have strings, but are replaced by bright of light. Users only need to pluck , as if plucking the strings, and can still play a melody. This production consists of two parts: a photosensitive circuit and a microcontroller. It can arouse interest in music and technology, and for friends who enjoy DIY, this is a good small production. I used to see a harp without strings, which is widely recognized by many visitors as the most interesting exhibit in the Pavilion! Visitors only need to reach out and pass through the black harp, and the tone be played. How can it play without strings? The staff revealed to us - he pressed the "light" button on the piano, and 14 red laser shot out from the top of the piano. He said, this is a laser harp. We use our fingers to flick the laser beam, and the harp make a sound, with each beam having a different pitch. It is said that this harp was originally placed in a in , mainly to arouse children's interest in music and technology. For friends who enjoy DIY, this is a good mini production. Power supply voltage: DC4.5V-5.5V. LED lights: 8. Power socket: DC-005 socket. Power cord: USB to DC-005 cable. Main board circuit board size: 8.9cm x 6.0cm. The principle of a string less qin (photoelectric qin): Photoelectric pianos do not have strings, but are replaced by bright of light. Users only need to pluck , just like plucking the strings, and can still play a melody. This production consists of two parts: a photosensitive circuit and a microcontroller. When the light beam of the light-emitting diode is blocked, the corresponding photosensitive resistor senses and produces a change in resistance value. The system composed of 7 photosensitive resistors produces a change in high and low potentials, and the microcontroller reads the changes in the high and low potentials of the photosensitive resistor to complete the input of operation instructions. The microcontroller controls the data to be mitted through the serial port based on the instruction information, which assigns values to the control port of the speaker and the control port of the water flow lamp to generate corresponding reactions. When there is light shining, the microcontroller reads the voltage of the photoresistor, and it is at a low level. When there is no light irradiation, the microcontroller reads the voltage of the photoresistor, and it is at a high level. In this way, when blocking the light of the laser, a switch effect can be generated in the circuit. It's DIY kits, needs to finish by yourself. (Delivered in parts; different factory batches may result in differences in the silk screen on the circuit board and the components, but this not affect the use) Color: Black Material: PCB+Components Package Contents: 1 * Electric Piano DIY Kits Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.