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One technique relay drivers from the microcontroller or computer can be made with the driver PNP transistors like the article "Interface Relays With PNP Transistor" ini.This circuit interface is simple and easily applied to a microcontroller or computer parallel port. Interface Relays With PNP Transistor uses 2 transistors 2N3904 and 2n2905/2N2907 UAH as a power relay drivers. The advantages of this circuit can menggeran relay with considerable power with TTL logic input from the computer and microcontroller. Source voltage required to follow the relay circuit is used, for example using a 12V relay, the source voltage to 12V or 24V relays the 24V voltage source. Detailed relay interface circuit and microcontroller or computer can be seen in the following figure.

Function diodes mounted parallel with the relay to prevent backflow into the transistor due to magnetic induction of the relay coil, therefore these diodes must be installed. For installation with a microcontroller or computer which need to be noticed is the Grund computer or microcontroller circuit must be connected to ground in series Interface Relays With this PNP transistors.

The switching output from one dc circuit can exist connected to pin 1 of opto-isolator (IC1) through a right current limiting resistor. Pin 2 of IC1 is stuck.

Pin 6 of IC1 is connected to lone foremost terinal of Triac (T1) through resistor R1 and pin 4 drives the gate terminal of T1.

To limit the rate of adjust of voltage, a snubber circuit (R2-C1) is added across T1.

at what time current passes through the inner LED of IC1, internal diac is triggered and the diac provides the gate pulse to T1. at this moment T1 is fired to drive the ac mains operated load by the side of its output.

past construction of the solid state relay on a joint pcb, enclose the undivided circuit appearing in a very unimportant ABS job. Now drill correct holes to mount four labelled input and output terminals. Since switching is accomplished by triac T1, don’t converge the domestic parts while AC supply is plugged in.