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Showing results for tags 'transistor'.
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I've just started playing around with my msp430 ez-2013 that my uncle gave me a while back (I've been too busy with school and whatnot until now ) and am trying to use the ez-2013 to control a transistor that will flash an externally powered LED. So far I've had no luck with it. I'm using a 2n222 transistor with a 10k ohm resistor from P1.0 on the ez-2013 to the base and a 10k ohm resistor on the emitter, with the anode of the LED attatched to the collector and the cathode attached to +6V. The resistor on the emitter is attached to ground. The led is powered seperately from the microcontroller (the MC is powered by USB) and the led/transistor is powered by 4 AA batteries. The transistor does work (the LED lights up when i connect the base to +6V) but does not turn on when attatched to the MC. I am just using the "Flashing the LED" program to eliminate the possibility of coding error. Is there something that I've done wrong, something I'm missing/have overlooked? Does the MC have to be powered by the same source as the LED or something in order for it to work? Would appreciate some help with my noob problem! Thanks in advance! Londonlad PS I attatched a photo of the setup, might provide some help in figuring out what I've done (wrong)
I'm trying to drive an NTE108 (BJT NPN) with an output pin on my MSP430G2553 and having trouble. The output (P2.4) of the MSP is connected to the base of the BJT through a 330 resistor and controlled via software on the MSP. I've attached a picture of the schematic (R1 is a recent addition). Pin P2.4 works as expected when connected to the LaunchPad. It can drive an LED and works when floating. I cannot test it with the BJT (NTE108) because I only have one and it is soldered down. I have moved the MSP over to a protoboard where it is supplied with a 3V regulator that can do 250mA. Now the problems start... P2.4 floats somewhere between 0.5V and 1.5V all the time. It has not been configured in software for pullup/pulldown resistors. It seems like there is some activity when the pin should change from the software, but the voltage variation is minimal. If the base resistor R10 is disconnected from P2.4 and connected directly to Vcc (3V), it turns on the transistor as expected and the motor runs. >> Maybe the MSP cannot supply the current to turn on the BJT... If the base resistor R10 is disconnected from the MSP430, the pin floats near 1.0V regardless of software control (should be 3 or zero). If R1 is disconnected, the same happens.>> Not a current supply problem. I have checked that the chip is properly grounded and receiving adequate power. I have moved the chip back to the LaunchPad and everything still works fine. Any thoughts on why the pin is floating and cannot be controlled? This is driving me crazy. I only have problems on the protoboard so it's probably something to do with connections, but I've tried to check what I can. Is there something I'm missing about moving the MSP430 from a LaunchPad to a protoboard? Thanks, Danny