Transistor 2N3904 de pequeña señal. El 2N3904 es un transistor de conmutación rápida, corta apague y baja tensión de saturación , adecuado para la conmutación y amplificación. El transistor es un dispositivo electrónico semiconductor utilizado para entregar una señal de salida en respuesta a una señal de entrada.
2N3903, 2N3904 2N3903 is a Preferred Device General Purpose Transistors NPN Silicon MAXIMUM RATINGS Rating Symbol Value Unit Collector–Emitter Voltage VCEO 40 Vdc Collector–Base Voltage VCBO 60 Vdc Emitter–Base Voltage VEBO 6.0 Vdc Collector Current – Continuous IC 200 mAdc Total Device Dissipation @ TA = 25°C Derate above 25°C PD 625 ... Since the 2N3904 is an NPN transistor, that means the base needs positive biasing (appropriate voltage levels and resistance) to turn on the collector emitter junction for proper current flow. Use of a load resistor (R1 above) is also important so there is not too much current being driven through the LED and transistor.
2N3904 Absolute maximum ratings Ta=25 °C Characteristic Symbol Ratings Unit Collector-Base voltage VCBO 60 V Collector-Emitter voltage VCEO 40 V Emitter-base voltage VEBO 6V Collector current IC 200 mA Collector dissipation PC 625 mW Junction temperature Tj 150 °C Storage temperature range Tstg-55~150 °C 2N3904, 2N3904 Datasheet, 2N3904 NPN General Purpose Transistor Datasheet, buy 2N3904 Transistor NPN General Purpose Amplifier This device is designed as a general purpose amplifier and switch. The useful dynamic range extends to 100 mA as a switch and to 100 MHz as an amplifier. Absolute Maximum Ratings* T A = 25°C unless otherwise noted * Microprocessor-Compatible 12-Bit D/A Converter, AD667KN datasheet, AD667KN circuit, AD667KN data sheet : AD, alldatasheet, datasheet, Datasheet search site for Electronic Components and Semiconductors, integrated circuits, diodes, triacs, and other semiconductors.
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 ... NPN switching transistor 2N3904 DATA SHEET STATUS Notes 1. Please consult the most recently issued data sheet before initiating or completing a design. 2. The product status of the device(s) described in this data sheet may have changed since this data sheet was published. Rev. C/CZ MMBT3904 SMD General Purpose Transistor (NPN) www.taitroncomponents.com Page 3 of 9 Fig.1- Delay and Rise Time Fig.2- Storage and Fall Time 2N3904 ELECTRICAL CHARACTERISTICS Ratings at 25¡C ambient temperature unless otherwise specified SYMBOL MIN. MAX. UNIT Small Signal Current Gain at VCE = 10 V, IC = 1 mA, f = 1 kHz hfe 100 400 — Output Admittance at VCE = 1 V, IC = 1 mA, f = 1 kHz hoe 140mS Noise Figure at VCE = 5 V, IC = 100 mA, RG = 1 kW, f = 10 É 15000 Hz NF — 5 dB Delay Time (see Fig. 1)