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<p>Great Instructable. I have one question. Since you're showing a positive <br> voltage to the base of the transistor it appears your schematic is <br>calling for a NPN transistor. In that case the negative lead of the LED <br>needs to go to the collector on the transistor rather than the emitter <br>as shown. Using a PNP transistor the emitter is the negative side but so <br> is the base. From the book Make: More Electronics by Charles Platt - <br>Transistors will work to some extent when reversed, although some <br>degradation may occur. You can use it the wrong way around and get some <br>results from a circuit, although not quite what you expect. If you then <br>discover your error and reverse it quite probably you still won&rsquo;t get <br>the results you expect, because the transistor has been damaged by <br>reversed polarity. I made mine running the negative lead of the LED to the <br>collector on a NPN3904 and it worked perfectly. Thanks.</p>
I made my version of this ible <br> <br>https://www.instructables.com/id/Dark-Activated-Night-Light/ <br> <br>hope you like it
Made one!
Why do you need a resistor for the led if you're using 3v?
does it matter if its a pnp or a snp transistor?, i did the hook up w/ supply voltage 2 aa batt. 1.5 each and does the size of the eldr matter? <br>
I haven't heard of an snp transistor....<br><br>As far as I know the size doesn't matter, but the one I used was about 4x5mm
thanks for the response , i meant npn . <br>
I don't honestly know the difference between the two. <br><br>Sorry for being useless &gt;.&lt;<br>I'm just a beginner in electronics really...<br><br>Thanks for checking out my 'ible though :-)
an npn transistor means it needs a positive volt to turn on and a pnp transistor needs a negative volt
and in this aplication i beleive you need a npn transistor
i have a quick question, can i change the LED into a motor?
I don't see why not... You would need to use a battery strong enough

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