555 Timer To Control Motors

  
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I am a mechanical engineering student, and for a part of my design project I wish to use a timer as so the motor switches off about 40-50 seconds after activation. The 555 timer chip is a rectangle with a indented o on the top, i assumed this was equivalent to the cutout semi circle (please tell me i don`t have the chip the wrong way around). With
555 Timer To Control Motors - schematic

the chip package in the orientation you describe, pin 1 is at the upper left, pin 2, 3, and 4 are below it, in order, on the left side. Proceeding around the package in an anticlockwise direction, pin 5 is at the lower right, then 6, 7, and 8. Pin 8 is opposite pin 1, at the upper right corner of the package. I have just had a look at the circuit and to run a motor you need a transistor to handle the current, it is most likely you have burned out the internal device. It can only handle 100ma or so. You need a power device and it should have the base connected to pin 3 then the collector to +V and emitter to the motor put a diode across the the motor terminals cathode to +V terminal with a 0. 1uF cap ceramic 32v for up to 12V supply. Use an NPN Tr. BFY50 or 2N3055 TIP3055 with a heat sink. You may need to use a Darlington configuration if the current is above 1. 5 amp for the motors, remember the starting current for a small DC motor can be 10 to 20 times is running current, and any load will demand a proportion more than no load. It depends on the torque required. I hope this helps you out some. There`s them that knows and them that just thinks they know, whitch are you Stir the pot and see what rises up. I have catalytic properties I get a reaction going. Here it is suggested a NPN power transistor. Be sure the output from 555 has also reverse diode protection as output from power transistor (another diode reverse...



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