Need help understanding outputs
Steven.S.
Posts: 4
Hello again,
···· I've spent hours trying to figure out how to get the SX28 chip to send an output current to the base of my BJT. In my code I set RB.7 to an output then I ran it. I expected to get Vdd coming out of that pin, but nope nothing.
Im using PortB since portC is taken up by a keypad and Im using RA.0 to control my LCD.
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···· I've spent hours trying to figure out how to get the SX28 chip to send an output current to the base of my BJT. In my code I set RB.7 to an output then I ran it. I expected to get Vdd coming out of that pin, but nope nothing.
Im using PortB since portC is taken up by a keypad and Im using RA.0 to control my LCD.·
Comments
Use a 150 ohm resistor.
Bean.
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Did you know that 111,111,111 multiplied by 111,111,111 equals 12345678987654321 ?
www.iElectronicDesigns.com
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Ohms law says that Voltage = Current times Resistance, or V=IR where V=Voltage, I=Current (in amps) and R=Resistance (in ohms)
To solve for resistance (because you know voltage and current), you would use R=V/I.
Thus:
30ma = 0.030 Amps
R = 5 / 0.030 = 166.7
The closest resistance value (and allowing for resistors that are not all that close to their published values) would probably be 150 ohms.
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John J. Couture
San Diego Miramar College
Yes, I should have explained how I got 150 ohms.
I was actually accounting for the 0.6 volt drop in the BJT.
So I used (5.0 - 0.6) / 0.030 = 146.66 Ohms.
Bean.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Did you know that 111,111,111 multiplied by 111,111,111 equals 12345678987654321 ?
www.iElectronicDesigns.com
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