2A302J is what electronic component ?
A quick Google search yielded that it is some kind of IC.
What does it look like? If you go to www.findchips.com and do a search on it, you get matches for both capacitors and resistors. The 302J part implies a value of 30*10^2 = 3000 somethings (Ohms for resistors, microFarads or picoFarads for capacitors).
What are the dimensions and shape of the component you are lookikng at? How many leads? Surface mount or through hole? If through hole, is it axial (leads straight out the ends) or radial (leads perpendicular to the component body)?
Could also be a 2SA302 transistor.
Sometimes they don't print the "2SA" part on the transistors.
Does it look like a transistor? Does it have 3 wires coming out of it?
This is the circuit
It's a transistor:
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