I have made the below circuit:


simulate this circuit – Schematic created using CircuitLab

I made the Arduino output turn on for 1 second, and off for 1 second(repeating square wave). I hear a faint clicking noise but suspect that full switch contact isn't being made as when I connect an LED to the NC pin of the relay, it is always on. And in the NO pin it is always off(this is why it seems to suggest that switch movement isn't being made fully). The relay I am using is the Aromat DS2YE-S-DC5V. It is the one with 8 pins in total.(Yes, the schematic is simplified for the relay, but the question is about if the coil is fully energizing). Is there something wrong with my circuit which is preventing the switch to move to the other contact completely? If you need any more info please ask.

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    \$\begingroup\$ Coil spec for S: 200 mW Thus @ 5V =40mA and base current must be 10% or 4mA. Do you have this? If Vout is reduced to 4.4 and Vbe=0.7 then Rb=3.7V/4mA = 920 Ohm \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 29 '17 at 4:36
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    \$\begingroup\$ I suspect you have the transistor connected incorrectly or the diode reversed. \$\endgroup\$ – Spehro Pefhany Jan 29 '17 at 5:07
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    \$\begingroup\$ diode test your NPN, check pins and wiring \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 29 '17 at 6:15
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    \$\begingroup\$ I made a rlly noob mistake...I mirrored the actual wiring. I didn't realize the schematic in the datasheet was from the bottom view(pin side)and so I accidentally mismatched the 5V and GND of the coil. Now it is working perfectly fine. Thanks for the help anyway! \$\endgroup\$ – zack1544 Jan 29 '17 at 6:25
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    \$\begingroup\$ So the diode was backwards... since the coil does not care about polarity. You might want to replace the transistor since it probably has been overheated. \$\endgroup\$ – Spehro Pefhany Jan 29 '17 at 6:35

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