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Author Topic: Help upgrading transistor (nevermind)  (Read 7585 times)

Offline d3x0r

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Help upgrading transistor (nevermind)
« on: February 26, 2012, 07:26:05 AM »
First, I have the same toroid coil for all of these, I'm using the same clip leads, and these are the scope shots of the base(yellow) and of a secondary pickup coil (blue).
First, is a bc347(I think might be mps06a or 2n2222); the first is without a resistor at all, and these all work;  The very first connection to the transistor is what I'm measuring.  Without a resistor, it spikes, and has a long lag, then continues to spike.  Then I have a variable resistor that I added, and at 2.9ohms it immediately starts, at a much higher frequency, the time scale shifts between most of these.  then a 42 ohm resistance, 209ohm 446, these all have a similar vertical spike of induction, all the way up to the max of this pot at 2370ohm.   
 
Which is where I started with this other mj15003 which is an npn, but good for more power.  at 2370ohm I get a large spike of inductance of the secondary, which trails off, and the voltage goes to 0 and stays there.
At 4.5k range I occasionally get a few spikes, but it stays open.
 
How can I apply other components to make this oscillate correctly?  Once it opens it stays open, and I never get a postiive potential on the collector again... so I guess the base isn't disengaging, even though it's going to open; maybe it's a broken part?  It is a broken part.  The transistor is open in all directions.   But the beginning notes on resistances is interesting :)