2n3055 transistor switching circuit
While it is difficult for us to get such a value of the resistor in the market so we can use the nearby value of the resistor i.e. Hence we have to attach resistor of 543 ohm with 470 ohm so to obtain the wanted output i.e. While if there is a need of 12V then between com and output 5V is available and for the rest 7V we need to select the appropriate value of the resistor. With the regulator output we directly got 5V minimum. Now assume that from the circuit we need 5V to 12V. Hence about 13.1 mA of overall current is available. Among the rotary switch and ground there is some amount of standby current of 2.5 mA approx. This implies that the value of current is 10.6 mA (as V =5V furthermore V=IR) existing among com and output. Imagine that the resistor which is attached between the com terminal and the output terminal of regulator has a value of 470ohm (R1). How to Calculate the Resistance Value for the Different Voltage?
#2N3055 TRANSISTOR SWITCHING CIRCUIT SERIES#
LM317 is the 3 pin series adjustable voltage regulator. If you use a 100 ohm/1 watt potentiometer then the output current is limited 3 Amps at 47 ohms and 1 Amp at 100 ohm. Pot RV2 is used to set the maximum current available at the output. Here 2N3055 transistors are used to get more current. In order to get 0V at the output we are using 3 diodes D7, D8 and D9. The minimum output voltage of LM317 voltage regulator 1.2V. Pot RV1 allows us to vary the output voltage in between 0 to 28V. So we need to use all the capacitors which are rated at 50v in the circuit. The rectified voltage at capacitor C1 is around 42.30V (30 volt *SQR2 = 30v *1.41 =42.30).
#2N3055 TRANSISTOR SWITCHING CIRCUIT FULL#
Huge heat sink is required in this circuit, as 2N3055 transistors produce large amount of heat at full load.Īlthough the voltage regulator LM317 protects the circuit from overheating and overload the Fuses F1 and F2 are used to protect the power supply circuit. This design can produce a current of 20 amps with little modification (use proper rating transformer and a huge heat sink with fan). 0-28V, 6-8A Power Supply Circuit Diagram using LM317 and 2N3055 In order to increase the upto 30v input of 30v should be applied. The above circuit uses only 15 v transformer at the input,so it can be varied maximum upto 15V. It is important to attach the voltage regulator IC LM317 to a heat sink as it tends to get hotter during operation. This circuit can be used as reliable DC source and acts as a replacement to batteries. With the help of this variable DC power supply, the output voltage can be varied from 1.2V to 30V at a current of 1A. 10KΩ POT is used for large change in voltage while 1KΩ POT is used for fine adjustments.ĭepending on the settings of the POT, the ADJ pin of LM317 receives a small portion of the output voltage as feedback and the output voltage is varied.Ī capacitor is used at the output of the voltage regulator so that the output voltage doesn’t have any spikes. In order to vary the output voltage, two variable resistors of values 1KΩ and 10KΩ are used. This pulsating DC is filtered using the capacitor to get a clean DC and is given to LM317 which is a variable voltage regulator IC. A bridge rectifier is used to convert this voltage to DC. The working of the circuit is as follows.Ī transformer is used to step down the AC supply to 24V at 2A. It is a robust, reliable and easy to use variable DC power supply. Instead of using batteries, which have a limited lifetime, a variable DC power supply can be used which is implemented in this project. For smaller voltages, we normally use batteries as a reliable source. A Variable DC Power Supply is very important for electronics projects, prototyping and hobbyists.