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It acts exclusively as an electrically controlled switch. The UJT is not used as a linear amplifier. It is used in free-running oscillators, synchronized or triggered oscillators, and pulse generation circuits at low to moderate frequencies (hundreds of kilohertz). It is widely used in the triggering circuits for silicon controlled rectifiers.
On one hand, intervening on the source is possible by using switching control techniques (increasing the efficiency), redesigning the circuit (costly and time demanding) and using soft switching transition. On the other hand, by adding external or internal filters (also costly) it is possible to address the propagation path. Fig. 1.
The most widely used electronic switch in digital circuits is the metal–oxide–semiconductor field-effect transistor (MOSFET). [2] The analogue switch uses two MOSFET transistors in a transmission gate arrangement as a switch that works much like a relay, with some advantages and several limitations compared to an electromechanical relay.
The control signal must be coupled to the controlled circuit in a way which provides galvanic isolation between the two circuits. Many SSRs use optical coupling. The control voltage energizes an internal LED which illuminates and switches on a photo-sensitive diode (photo-voltaic); the diode current turns on a back-to-back thyristor ( TRIAC ...
Open outputs configurations thus differ from push–pull outputs, which use a pair of transistors to output a specific voltage or current. These open outputs configurations are often used for digital applications when the transistor acts as a switch, to allow for logic-level conversion, wired-logic connections, and line sharing.
Essentially, a chopper is an electronic switch that is used to interrupt one signal under the control of another. In power electronics applications, since the switching element is either fully on or fully off, its losses are low and the circuit can provide high efficiency.
Substantial snubber circuits are added around the device to limit the rise of voltage at turn off. Resetting the snubber circuit usually places a minimum on-time requirement on GTO-based circuits. The minimum on- and off-time is handled in DC motor chopper circuits by using a variable switching frequency at the lowest and highest duty cycle.
A circuit diagram (or: wiring diagram, electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an electrical circuit. A pictorial circuit diagram uses simple images of components, while a schematic diagram shows the components and interconnections of the circuit using standardized symbolic representations.