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a transistor circuit for driving the coil of a magnetic relay.

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13y ago

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How do you interface a relay to a microprocessor type 89C51?

you cannot directly interface a relay to a microcontroller, you need a buffer circuit in between the two, you can use a NPN transistor BC 547, connect the controller pin directly to the base of the transistor (since there is an internal 10k pull up resistor inside the controller no need of any base resistor). Connect the transistors emitter to the gnd & the collector to the relay coil, the another end of the relay coil goes to the supply, check this link for complete information http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Relay-Interfacing.html


What economical device - varistor - transistor etc can you use to supply power to a relay until the voltage drops to 10.5 volts?

A zener diode, a transistor, a rectifier diode, and a few resistors. A 10.5V zener diode will conduct until the voltage across it drops to below 10.5. If the relay is small enough, a zener diode is all you need. However, more than likely the current draw of the coil would burn the zener out. Use the zener to drive a transistor, and use the transistor to trigger the relay. V+ | |_______________________ | | _|_| _____|___ |/ \ 10.5V | | /___\ | 3 Relay | __|__ 3 Coil | / \ 3 0---------- /___\ 3 | | | 3 \ \ 4.7K | | / 2.2K / |____ ___| \ \ | / / | | | B | / C | |________|/ | |\ 2N2222 | | \ | | E |______________________| | _|_ \\\ When the voltage is above 10.5V the zener will conduct ant turn on the transistor. The transistor will power the relay. When the voltage drops below 10.5V the zener will stop conducting, shutting off the relay. The rectifier diode absorbs transients caused by the field breakdown in the coil, protecting the transistor. Just a plain resistor will do it or you may follows suggestion and use a computer to do that. The last time i used those ancient devices i find out they operate as a current device like minimum pull in current source. So a passive resistor in series will insure the minimum pull in source however it could be higher then the 10.5 v you need.The above designi just plain silly.


What is Si transistor?

A silicon transistor is a transistor made of silicon.


What are the Similar transistor for 221334 PNP transistor?

Similar to a 2N3906 PNP transistor


What is rt in electronics?

I believe that is resistor transistor technology TTL transistor transistor logic

Related Questions

What is a driver transistor?

dirver transistor is added in a circuit so as to provide required voltage at an operating current which can not be provided by the microcontroller


When using an arduino controlling a relay- why are resistors used with the transistor to activate the relay coil?

Because without the resistor, there would be a short from the base to ground, and sometihng would smoke.


Where is the fuel pump relay located for a 1992 corvette?

Primary Relay is located: Seating area, center, behind dash, driver side of stereo receiver, mounted in relay block. Secondary Relay is located: Seating area, driver side, behind dash, driver side of steering column, above lower dash panel, mounted in relay block


Where is the horn relay located on a 1993 Silverado?

Front seating area, driver side, behind dash, driver side of steering column, mounted in relay block . To the right of the flasher, If you pull that relay and check the diagram on the relay you can shoot power directly to the horn from the hot side of relay terminal


Name the device that receives a signal and retransmit it at a higher level of higher power?

A relay or repeater. EDIT: The bipolar junction transistor


Where is fuel pump relay on mustang?

UNDER THE DRIVER SEAT


1990 300zx fuel relay location?

the Fuel pump relay is inside the driver's front wheelwell to the right


Where do you find the relay switch on a 1988 ford escort?

The starter relay is on the driver's side fender behind the battery.


WHere is the relay fuse located on a 96 neon?

the relay fuses are in the engine compartment on driver side with the mini fuses


Where is the flasher on the 1985 Toyota pickup?

Flasher Relay is located Front seating area, driver side, under dash, driver side of steering column, mounted in relay bracket.


Where is the fuel pump relay on a 1989 Ford Probe lx?

Front seating area, driver side, behind dash, driver side of steering column, mounted in relay block


How many flasher relay's do you need for full function in a 1979 camaro?

It has 2. The turn signal flasher relay and the Hazard flasher relay. Hazard signal flasher relay is located: Front seating area, driver side, driver side of steering column, under dash, mounted in upper left corner of fuse panel. Turn signal relay is located: Front seating area, driver side, driver side of steering column, behind dash, mounted on lower right corner of fuse block.