Electronics Co. Ltd. is a PT91-21C/TR10. This part is a NPN Silicon type phototransistor which features high speed response time and high sensitivity with a low noise amplifier. The device has a light current of 30mA and a power voltage of 30V. It is able to detect and amplify weak CD signals. The phototransistor is encased in a 3 pin package, which allows for simple installation. The device is ideal for smoke and flame detection, general purpose light sensing, and small object detection.