5v relay problem

[firemedic]

I'm finishing up my TOS build. It still needs a little tweaking but I have a problem: I'm using the 5v channel switching relay and it doesn't work. The NC terminals stay closed when 6vDC is applied. The relay is not marked. So I checked to see if I picked the wrong coil connections. I connected the two on the other side of the relay (to 6vdc) which read 125r across them, but it still doesn't change. NC is still closed. The LED works.
BTW I am using the 5v rectifier connection from the PT since that wasn't being used ( I have a 5V filament trans. suppying the rect.). It is going into a bridge rect. and a 10,000 uF 50V filter cap. this gives me 6.5 volts no load, 6.1V with the LED on. The CL resistor to the LED is 100R.

Does anyone know exactly how this relay is wired?

[JayB]

10,000uf cap to filter just for a relay?   That's pretty big. I'd go for something along 470uf.

If you can draw it out exactly how you wired it up, we be able to see better what you have done. Do you have a diode across the coil? If the polarity of the diode is wrong, your relay will not work.

The other thing is, if you got the relay and led in series with each other, make sure the led comes before the relay. LED->Relay->ground.

[firemedic]

I wanted a nice smooth DC current, due to the wires going right by a few signal wires. Plus I do have room for a big cap.
The LED is in parallel.
I've attached a crude sketch. I just don't know for sure which terminals are the relay coil.
BTW I have the clean channel at least pretty much dialed in. Pretty awesome.

[sluckey]

Are you using Doug's relay? If so, here's the pin assignments...


If you are using a different relay just use your ohm meter to find the coil. The coil will be the only two terminals that have a non-zero (or non infinity) ohms resistance reading.

[firemedic]

Thx sluckey, I think I may have the coil wired backwards.

[sluckey]

What do you mean 'backwards'? The coil don't care which terminal is positive or negative. However, if you have a despiking diode across the coil then you MUST connect the positive voltage to the coil side that has the diode CATHODE connected.

[firemedic]

Well I switched the positive & negative leads on the coil & it works now. Thanks a million for the wiring diagram!
Just a little more tweaking......

[JayB]

What do you mean 'backwards'? The coil don't care which terminal is positive or negative. However, if you have a despiking diode across the coil then you MUST connect the positive voltage to the coil side that has the diode CATHODE connected.

Some relays you have to follow their polarity. Why? You got me.  I got some NEC's that will only work one way. The relays that Doug carries, it doesn't matter what polarity you use.

[phsyconoodler]

The coil is not the problem here,it's the DIODE orientation.If you swapped the leads and it works,then the diode was installed backwards.

[firemedic]

Ah, but I kept the diode orientation the same on the leads.....everything was the same except the "polarity" of the coil. I'm glad in a way there is some disagreement on this since I thought polarity wouldn't matter too. That's why I didn't bother switching the leads before I posted.
At any rate, it works now. I'm happy.

Oh, now I get what you're saying about diode orientation. OK. Still works.

[PRR]

I think some sensitive relays have a permanent magnet in addition to the electromagnet. If you wire coil right, they add; if wired wrong, they fight and it don't clack.