 How do my brand new ICs not work?
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Arcstarter
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Fri Dec 31 2010, 12:49AM
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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
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Well i am trying to make a variable voltage flyback driver with a uc3842. I have 5 brand new samples i got about a year back, still in the antistatic tubing. I put it on a breadboard and hooked up a timing cap and resistor, and i cannot get it to oscillate. The Vref is at 0v when it should be at 5, and there is no output. There is zero volts on all pics except for pin 7 which has 12v on.
Here is the schematic i am trying to test it with. Is there something wrong with it? I have been studying the datasheets and this is basically how it is used, minus the Vfb and current sense, just an open loop oscillator. Shouldn't i at least get 5v on the Vref output with the two supply pins connected?
EDIT: Nevermind, i forgot about the minimum startup voltage  Thanks to Erlend for pointing it out without making me feel like an idiot, even though i do anyway
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