Problem with Relay experiment (Make: Electronics #7)

[OgreSwamp]

Hi there,

I'm reading Make: Electronics to recover my college electronics knowledge.
I've assembled a circuit (using a breadboard, during it with alligators is a nightmare) and it doesn't really work.

So here is a circuit I'm trying to do:

Here is what I've done:

Resistor is 680Omh, LEDs positioned properly (cathodes facing right - to the negative, green wires).
When I press red button (bottom left corner) I can hear the relay is switching, top led goes off, but bottom one doesn't start.

I've tried few things:
1) replace a relay component
2) replace LED
3) tried to measure voltage at 2nd led pins when I press red button

1 & 2 doesn't help.
Voltage goes up to 0.4-0.6 for half a second and then drops to zero when I press/release the button.
Can't figure out what's wrong. My only guess was that DPDT relay I've bought isn't the correct one, but I found the data sheet and it says that coil voltage is 12v - came as my circuit voltage.

Here are few more pictures to get a better understanding what's happen there.

Thanks!

 

[davenn]

Welcome to EP

so what is or isn't happening ?

can you hear the relay click when you push the switch ( will probably be a reasonably faint sound) ?

Dave

 

[OgreSwamp]

Hi, thanks!
yes, I can hear the click. I've described problem under the second photo:

Resistor is 680Omh, LEDs positioned properly (cathodes facing right - to the negative, green wires).
When I press red button (bottom left corner) I can hear the relay is switching, top led goes off, but bottom one doesn't start.

I've tried few things:
1) replace a relay component
2) replace LED
3) tried to measure voltage at 2nd led pins when I press red button

1 & 2 doesn't help.
Voltage goes up to 0.4-0.6 for half a second and then drops to zero when I press/release the button.
Can't figure out what's wrong. My only guess was that DPDT relay I've bought isn't the correct one, but I found the data sheet and it says that coil voltage is 12v - came as my circuit voltage.​

 

[KrisBlueNZ]

Hi there and welcome to Electronics Point

That's a very good problem description!

It looks to me like you've done everything right.

Is it possible your breadboard is damaged?

Try moving the LEDs and the resistor, and the +12V feed to the common contact, over to the other side of the relay, so you're using a different part of the breadboard.

 

[OgreSwamp]

Kris,
thanks for your help. A guy from another forum pointed that relay drawing in data sheet isn't same as relay from the book.
The relay's "pole" I'm using (shared contact) has pins right after the coil. Relay from the book has pole between 2 other contacts. So I switched left LEDs anode and probe from push button. And everything works fine now

E.g. on the firs picture if we're going from top to bottom contacts pairs are - Throw, Pole, Throw, Coil.
The relay I'm using is T, T, P, C

Thanks again. Hope that may help someone in the future.