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I work on the book "Make - Electronics" doing some experiments. One of these is working with a relay. The simple schematic is this one:

enter image description here

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?

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  • \$\begingroup\$ What relay do you use? And why don't you have a diode on the coil? \$\endgroup\$ – Gregory Kornblum Jun 22 '16 at 17:43
  • \$\begingroup\$ I use a Printrelais 9 V/DC 10 A 2 Wechsler Zettler Electronics AZ733-2C-9DE Actually I just sticked to the schematic for the time being. \$\endgroup\$ – sesc360 Jun 22 '16 at 17:45
  • \$\begingroup\$ Maybe I should add, that when pressing the button, I hear the relay switch. \$\endgroup\$ – sesc360 Jun 22 '16 at 17:46
  • \$\begingroup\$ Can you take a picture of the circuit for us? \$\endgroup\$ – pgvoorhees Jun 22 '16 at 17:47
  • \$\begingroup\$ I definitely can, but need to do that later, as I am unfortunately not at my desk right now \$\endgroup\$ – sesc360 Jun 22 '16 at 17:47
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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: -

enter image description here

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  • \$\begingroup\$ I think I do not completely understand, isn't that what is already shown in the schematic? The left is supposed to glow when the button is not pressed and the right LED is connected to the middle pole which should only light up when I press the button and close the connection.. isnt the relay I have normally closed? \$\endgroup\$ – sesc360 Jun 22 '16 at 19:12
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    \$\begingroup\$ Your schematic is correct but your interpretation of the relay pins is suspect I believe. \$\endgroup\$ – Andy aka Jun 23 '16 at 7:12

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