Q: Relay circuit not switching as expected I work on the book "Make - Electronics" doing some experiments. One of these is working with a relay. The simple schematic is this one:

The circuit that I build works to 95%..... The left LED is lighting up when connecting to power, which means the relay is passing through the current. When I press the button, the left LED is turning off correctly, but the right one doesn't light up. I tested both LEDs by switching their places and got the same result. So I know that both LEDs are working. But i do not find the error... So I would think the relay is working, right?

A: Try swapping the two red connections on the relay. It's highly possible that you are feeding the positive supply to the normally closed contact instead of the "pole". If you look at the DS it shows the pole connection in the middle of the row of three contact connections: -

