Switch ICs with Adjustable Current Limiting Schematic Circuit Diagram

Transistors are often used for switching power supply voltages. MOSFETs are most often used, since they have low ‘on’ resistance, and they are also available for large currents. What a discrete transistor or MOSFET lacks are protective functions, such as current limiting and overtemperature protection. The MIC2545A from Micrel can provide a solution to this[…]

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Lock code unit with auto reset

The code unit, which operates with was designed to control an electromagnetic door lock with a four-digit code. It resets automatically after a short period. The keys that set code are designated S1-84 in the diagram. Each of them is linked to a bistable (flip-flop) in IC1. The connections are arranged so that when key[…]

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Low-drop a.c. switch for 12 V halogen lights

Because of their inertia, power consumption, contact wear, and often size, relays are not really suitable for switching alternating voltages. Moreover, they cannot be used in phase control circuits. Replacing them by triacs may give problems owing to the forward voltage drop across these devices. A much better solution is the use of anti-series-connected SIPMOS transistors.[…]

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Thyristor starter for fluorescent tubes

The Type Y1112 fluoractorTM form Taxes instruments a specially designed thyristor for starting fluorescent tubes. Its main advantages over a standard thyristor are its much greater hold current. its ability to cope with rapidly rising anode-cathode voltages (high du/dt value), and its overvoltage protection. These properties make it very suitable to replace a traditional electro-mechanical[…]

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