Over Voltage Protector. Simple Design 9


This is one simplest form of Over voltage Protector for the Bread board power supply. Usually we use 12 volt DC power supply to power the bread board. If the CMOS devices are used in circuit assembly, over voltage can damge them permanatly. This circuit limits the voltage to the bread board to 12 volts. If the voltage increases above 12 volts due to a high voltage surge in the AC lines ,the circuit cut off the power to the bread board. It can also be used in any device like Chargers that works on 12 volt DC .
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SCR Latching Circuit. Design Note 21

SCR Silicon Controlled Rectifier ( SCR) is a semiconductor device used in switching applications. Unlike Transistors, SCR latches once triggered and remain on even if the triggering voltage at the gate is removed. The device can be switched off by removing the Anode current through a Push- to- off switch or by disconnecting the power supply.
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SCR and its Applications.Design Note 1


Silicon Controlled Rectifier (SCR) is a kind of semi conductor device used in switching applications. When a positive voltage is applied to its gate, SCR conducts and latches. It remains conductive even if its gate current is removed. The latched SCR can be switched off by removing its Anode current.
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How to remove Rate effect and Backlash effect from Triac? Solution File 1

Triacs are the most common semiconductor devices used in power control and switching applications. The electronic power control circuits are designed to control the distribution or levels of AC or DC power sources. Such power control circuits can be used to manually switch power to electrical devices or to switch power automatically when parameters such as temperature or light intensities go beyond preset level. Triacs are borne with some inherent drawbacks, which will reflect in their working.

Rate effect is the unwanted effect on triac controlled circuits caused by the transients in the AC line which causes erratic functioning of the circuit. Backlash Effect is seen in Lamp dimmer circuits using triac and sometimes the lamp never turns on when the control pot is turned fully. Here are the tricks to solve both the problems.

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Clock Controlled Relay Driver. Design Trick 14

Don’t miss your favorite TV programme or don’t forget to irrigate garden. This clock controlled circuit will actuate a relay to switch on the AC load to perform the function at the right time. Operation of the circuit is simple. It receives the triggering pulse from the buzzer terminals of the clock and an SCR triggers to activate the relay. The only drawback of the circuit is that, it is necessary to switch off the load manually by turning off the power. You can do experimentation to make an automatic operation also.

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