ToshibaEStudioFileErSoftwareUsing Transistor as a Switch. December 2. 3, 2. Electronics. Most of microcontrollers work within 5 volt environment and the IO port can only handle current up to 2. A therefore if we want to attach the microcontrollers IO port to different voltage level circuit or to drive devices with more than 2. A we need to use the interface circuit. One of the popular method is to use the Bipolar Junction Transistor BJT or we just called it transistor in this tutorial. I have to make clear on this BJT type to differentiate among the other types of transistors family such as FET Field Effect Transistor, MOSFET Metal Oxide Semiconductor FET, VMOS Vertical MOSFET and UJT Uni Junction Transistor. A. The Switch. The transistor actually works as a current gainer any current applied to the base terminal will be multiplied by the current gain factor of the transistor which known as h. FE. Therefore transistor can be used as amplifier any small signal very small current applied to the base terminal will be amplified by the factor of h. FE and reflected as a collector current on the collector terminal side. Learn how to do just about everything at eHow. Find expert advice along with How To videos and articles, including instructions on how to make, cook, grow, or do. All the transistors have three state of operation Off state in this state there is no base current applied or IB 0. Descargar Cabellos Para Sims 2 more. On active state in this state any changes in IB will cause changes in IC as well or IC IB x h. Toshiba-E-Studio-5520C-6520C-6530C-FC-2330C-2820C-2830C-3520C-Remote-Scan-Driver-Manual-8.jpg' alt='Toshiba E Studio File Er Software' title='Toshiba E Studio File Er Software' />FE. This type of state is suitable when we use transistor as a signal amplifier because transistor is said is in the linear state. For example if we have a transistor with gain of 1. IB from 1. 0u. A to 1. Escada Limited Edition Fragrances. A this will cause the IC to swing from 1. A to 1. 00. 00u. A 1 m. A to 1. 0 m. A. On saturate state in this state any changes in IB will not cause changes in IC anymore not linear or we could say IC is nearly constant. We never use this state to run the transistor as a signal amplifier class A amplifier because the output signal will be clamped when the transistor is saturate. Join the NASDAQ Community today and get free, instant access to portfolios, stock ratings, realtime alerts, and more Join Today. Toshiba E Studio File Er Software' title='Toshiba E Studio File Er Software' />This is the type of state that we are looking for on this tutorial. From the picture above we could see the voltage and current condition of transistor on each state if you notice when transistor is in off state the voltage across collector and emitter terminal is equal to the supplied voltage, this is equivalent to the open circuit and when transistor is in saturate state the collector to emitter voltage is equal or less then 0. Volt which is equivalent to the close circuit. Toshiba/how-to-install-printer-driver-program-for-Toshiba-printer-5.jpg' alt='Toshiba E Studio File Er Software' title='Toshiba E Studio File Er Software' />Therefore to use transistor as a switch we have to make transistor OFF which equivalent to the logical 0 and SATURATE which is equivalent to the logical 1. One of the famous diagrams that show the transistor operating state is called the transistor static characteristic curve as shown on this following picture When we operate transistor as the class A common emitter amplifier usually we choose to bias the transistor apply voltage on VBE and VCE in such a way Q Point that IC and VCE output will swing to its maximum or minimum value without any distortion swing into the saturation or cut off region when the IB input swing to its maximum or minimum value but when we operate the transistor as switch we intentionally push the transistor into its saturation region to get the lowest possible VCE i. ON switch ON and into its cut off region when we need to make the transistor OFF switch OFF. The above diagram show a typical microcontroller interface circuit using NPN transistor the RB resistor is used to control the current on base terminal that make transistor OFF and ON saturate while the RC resistor is the current limiter for the load. Vcc you can by pass the RC not use. Notice the diode also known as the clamp diode in the inductive load circuit is needed to protect the transistor again the EMF Electromotive Force voltage generated by the inductor component when the transistor is switched on and off rapidly, this voltage is oppose the source voltage. The diode will act as a short circuit to the high voltage generated by the inductor component, you can use any general purpose diode with capable on handling minimum 1 A of current such as 1. N4. 00. 1, 1. N4. On the picture shown above you could see how we connect the transistor as the high active switch logical high also known as low side switch using NPN transistor and the low active switch logical low also known as high side switch using PNP transistor. Ok lets calculate each of the RB and RC value on this following NPN transistor circuit On the circuit above we are going to use 2. N3. 90. 4 the cheap general purpose transistor where you could easily found on your local market to drive 5 LED from microcontroller port, from the 2. N3. 90. 4 datasheet we get this following information IC max 2. A this is maximum value that will make your transistor smoked, in practical application always use just half of the maximum value mentioned on the datasheet, h. FE 1. 00 to 3. 00, VBE saturate 0. Volt, VCE saturate 0. F-J4qpBunVg/hqdefault.jpg' alt='Toshiba E Studio File Er Software' title='Toshiba E Studio File Er Software' />Volt. For most transistor in general we can use VBE 0. Volt should be saturate and VCE 0 Volt. Using the 5 volt power supply VCC and assuming VLED 2 Volt, with each of them consuming 1. A, we could calculate the RC value using the Ohms law as follow IC 5 x 1. Rpv Reports Crack. A 7. 5m. A 0. 0. A, this current is still far bellow the maximum IC allowed by 2. N3. 90. 4 transistor. RC VCC VLED IC 5 2 0. Ohm. Power Dissipation on the RC resistor will be. P VCC VLED x IC 5 2 x 0. Watt. Base on the above calculation we could use the nearest higher value available on the market which is 4. Ohm, 0. 5 watt resistor for heat dissipation usually we use twice of the watt value calculated. Assuming the h. FE minimum is 1. LED is IC h. FE x IBIB IC h. FE 0. 0. 75 1. A 0. A This current can easily be supplied by most microcontroller IO port which is capable to drive up to 2. A output current. Again by applying the Ohms law we could calculate the RB value as follow RB VPORT VBE IBAssuming the minimum average voltage of microcontroller IO port VPORT with logical 1 is about 4. RB 4. 2 0. 7 0. Ohm. Power dissipation on the RC resistor will be. P VPORT VBE x IB 4. Watt. Base on the result you could use 4. K7 Ohm, 0. 2. 5 Watt resistor this is the common resistor which you could easily found on the local market i. Use this RB calculation as your maximum reference value in the real world most of the transistors h. FE is vary and being measured tested with different VCE and IC value not to mention different specification even though you use the same transistor type. Therefore the real RB value could be lower than 4. K7 if you really want to drive the transistor into its fully saturate mode where the VCE near 0. Now the question is how we determine the exact valueTo answer to this question I build this following testing circuit base on the RC and RB calculated value above using the Atmel AVR ATTiny. LED Note the reason I used RC 31. Ohm because at that time I run out the required 4. Ohm resistor, therefore you could use just single 4. Ohm resistor or if you only have 1. Ohm as I did, you could use them as I did. Bellow is the C Program that I used to test this circuit. File Name trswitch. Version 1. 0. Description Transistor as Switch Simple LED Blinker. Author RWB. Target Atmel AVR ATTiny. Microcontroller. Compiler AVR GCC 4. Win. AVR 2. 00. 90. IDE Atmel AVR Studio 4. 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