Judging the quality of infrared light strips  & infrared light emitting diodes as same with judgment of ordinary diode.  the infrared light emitting diodes emitting power is about 100mW. Luminous efficiency of infrared light emitting diode with a special instrument for determination, and amateur conditions, can rely on the experience with the roughly distance determination method. The infrared receiving tube receiving circuit is a photosensitive diode,  infrared receiving diode reverse bias need bias voltage be good for work and obtain high sensitivity.
How it works about infrared control system？
Actually it’s infrared photosensitive resistance. The supply voltage is small in ultra low resistance state when infrared irradiation is waked. the other way round：supply voltage is big when infrared after light off in a high impedance state is close to the 6K, a big portion of the whole, general points to more than 4V is no problem. In generally The infrared receiving diode are rotundityr and quadrate two types. Because the transmitting power of the infrared light emitting diodes are small, weak signal received by the infrared receiving diode, so the receiver will increase the high gain amplifier circuit. But now it is amateur or formal products, mostly by product integrated receiver,  Integration of infrared receiving head is a set of infrared receiving, amplifying, filtering and comparator output module, it’s stable performance, reliable. So, with integrated receiver module, user no longer make a receiving amplifying circuit, so the infrared receiving circuit is not only simple but also greatly improved the reliability .