“Hey… The resistor isn’t connected to the battery!”
This was me, after many frustrating hours of trying to figure out what was wrong with a circuit I’d built.
It was such a stupid mistake.
And I was of course blaming everything from the manufacturer of the resistors to disturbance from the WiFi signal.
But it turned out that the resistor was just not connected properly.
And here’s the method I used to find it (this method is best to do with a friend):
-Print (or draw) your schematic diagram on a piece of paper
-Your friend looks at the schematic diagram, while you look at your circuit
-Your friend starts at the positive supply and tells you what it should be connected to
-You check your circuit and say yes for everything that you have confirmed is there
-Your friend marks each connection in the circuit diagram as checked
-Do this until all the connections are checked
Example:
FRIEND: The positive terminal of the battery is connected only to one side of R1
YOU: Correct.
FRIEND: The other side of the resistor R1 is connected to the base of transistor Q1, and to one side of the resistor R2.
YOU: Correct.
FRIEND: The other side of R2 is connected to ground.
YOU: Heeeeey. Wait a minute….. It’s not!
…and so on.
I’m writing about debugging in the upgraded version of «Getting Started With Electronics», so I felt like sharing 
But you’ll also learn about what all the basic component does. And how to build things like a siren circuit, blinking lights or a stereo amplifier.
You can find more info here:
http://www.build-electronic-circuits.com/products/getting-started-with-electronics-ebook/
Keep on Soldering!
Oyvind
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