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Topic: problems switching transistor variable voltage power supply. (Read 671 times) previous topic - next topic


i'm new to the forum arduino and electronics.   im workin with a basic tank circuit.  two inductors in series and a capacitor in parallel with a 9v battery.  i am controlling the circuit on and off with a npn transistor.  i have a diode in place as if the cuircut were a dc motor. not sure if it is needed? the base of the transistor  is connected to pin 9 on the arduino. no resistors in place.  i have a potentiometer connected to analog pin 0 and use it to vary how long pin 9 is off( as in the blinking LED example).
this works as i would expect and my coils (inductors)pulse.

i usually use this tank circuit with a variable voltage power supply. 2-24 volts. im not sure the amperage. hoping to test soon. but I'm guessing 4-5 amps max.  so un hooked my battery and tried the variable power supply.  now pin 9 is dead. i.e. it does not shut off. verified by running a blinking LED code.  all other pins seem to work correctly. =( . 

so i started looking for other circuit diagrams while i wait for a new atmega chip, some have resistors in place between the pin out and transistor. but im not to sure where to find a solution.



heres a link to a pic . i'm trying to use the arduino to replace the mechanical switch. 
the transistor i'm using is TIP3055. 

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