PHOTO TRANSISTOR SWITCH CIRCUIT SERIES

Technical Specifications of BD140 Transistor are:ДЈ) Max Collector-Emitter Voltage (VCE): вЂ“80VД¤) Max Collector-Base Voltage (VCB): вЂ“80V Technical Specifications of BD139 Transistors are:ДЈ) Max Collector-Emitter Voltage (VCE): 80VД¦) Max Collector Dissipation (Pc): 12.5 WattД§) Max Transition Frequency (fT): 190 MHzДЁ) Minimum & Maximum DC Current Gain (hFE): 25 вЂ“ 250Д©) Max Storage & Operating temperature Should Be: -55 to +150 Centigrade It can be used to control the power delivered to the load, in inverters and choppers.ДЎ) The power transistor cannot be operating satisfactorily above the switching frequency of 15 kHz.Дў) It can be damaged due to thermal runaway or second breakdown.ДЈ)It has a reverse blocking capacity is very low. Similar to other transistors they also have 3 pins and their pin configuration is shown in the image above.ДЎ) It is very easy to turn ON and turn OFF the power transistor.Дў) The power transistor can carry large currents in ON state and block very high voltage in OFF state.ДЈ)The power transistor can be operated at switching frequencies in the range of 10 to 15 kHz.Д¤)ON-state voltage drops across the power transistor are low.

PHOTO TRANSISTOR SWITCH CIRCUIT SERIES

The Transistors of this series are generally designed to generate extra power and hence they are a bit bigger than other transistors.Д«D 139 transistors are NPN transistors and BD140 transistors are PNP transistors. Out of these, there is another kind of Transistor series the BD series which is a power transistor series. Transistors are available in various types of packages such as 2N series or the Surface mount MMBT series they all have their specific advantages and applications.

The FET transistors have high current gain than BJT transistors. The FET transistors have control over the size and shape of a channel between source and drain which is created by an applied voltage. For the connections in the circuit, we also consider the fourth terminal called base or substrate. FET transistors are classified into Junction Field Effect transistors (JFET) and Insulated Gate FET (IG-FET) or MOSFET transistors. The FET transistors have three terminals they are gate (G), Drain (D), and Source (S). On the other hand, PNP transistors use Holes as their majority charge carriers and It consists of two p-type layers separated by an n-type layer.Дў) Field Effect Transistors: Field-effect transistors, are unipolar transistors and use only one kind of charge carrier. It consists of two n-type layers separated by a p-type layer. In NPN transistors electrons are the majority charge carriers. BJTs are of two types known as NPN and PNP transistors. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between two other terminals, making the device capable of amplification or switching.

1) Bipolar Junction Transistors: A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and holes as charge carriers.

Photo transistor switch circuit