T541a datasheet 2n3904


2N3904 NPN General Purpose Amplifier . This device is designed as a general purpose amplifier and switch. The useful dynamic range extends as a switch and to 100 MHz as an amplifier.. The 2N3904 is used very frequently in hobby electronics projects, including home-made ham radios, code-practice oscillators and as an interfacing device for microcontrollers . 2N3904 General Purpose Transistors NPN TO-92 Page 1 12/05/08 V1.1 High Speed Switching Features: • NPN silicon planar switching transistors. • Fast switching devices exhibiting short turn-off and low saturation voltage characteristics. At 20mA, that's about 120 Ohms. The current gain depends on the collector current, but figure on 50. With a base current of 20mA, that's a collector current of way more than the 2N3904 can handle, so 20mA will saturate it thoroughly. You can probably get by with a lower base current. Look at a 2N3904 datasheet for gain at different collector ...