I have a output of .03v from my logic gate but i need it to be 5v to enable my dc motor. How can i amplify it into 5v using a transistor?
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1\$\begingroup\$ What is the voltage output of your logic gate if the motor is disconnected? \$\endgroup\$– Dwayne ReidCommented Sep 21, 2018 at 1:41
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\$\begingroup\$ The output is exactly 5v if the motor is disconnected \$\endgroup\$– icekingCommented Sep 21, 2018 at 1:54
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1\$\begingroup\$ Okay - just look through the many questions on this site that explain how to control a motor from a logic signal. \$\endgroup\$– Dwayne ReidCommented Sep 21, 2018 at 2:02
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\$\begingroup\$ I'm not in front of my computer right now, so it is difficult for me to find you a link. \$\endgroup\$– Dwayne ReidCommented Sep 21, 2018 at 2:02
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2\$\begingroup\$ @Yajeep: We like folks to do some basic research before asking questions. Please read the datasheet for the 4070B and see what its maximum output current is and compare this with the current that will be required by your motor. (Measure its resistance and use Ohm's law.) \$\endgroup\$– TransistorCommented Sep 21, 2018 at 2:29
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2 Answers
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The logic gate is not able to provide enough current and hence the voltage is dropping as motor tries to pull more current. You can use a power NPN Bipolar Transistor (like TIP122) as a switch to drive the motor. Connect the gate output to base of transistor in series with 100 ohms and the motor to collector of transistor. Supply collector with 5 V from external power supply. Ground the emitter. Also add a diode in reverse bias in parallel with the motor for protection.
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You could imagine the current the motor requires is somewhat higher than the one your logic gate is able to provide. So this seems to be a current protection inside the ic not to damage it, thus reducing output voltage. In order to drive your motor you could use a transistor, one which is able to work under the current specs of your motor.
