5-90
NAXJA Forum User
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Muad'Dib said:I have a relay question and i figured i would post it in this thread...
I have both SPST and SPDT relays that im wiring up. Im using the SPDT Relays as SPST's (basically just not using 87a).
From what i understand, 85 and 86 on the relay can be wired anyway you want too. So the switched +12v can go to either 85 or 86 as long as the other is used for ground.
Is the same principle true for 30 and 87? When the coil is energized and the internal switch closes completing the connection between 30 and 87 i wouldnt think it would matter which way the voltage and current is flowing... Am i wrong here?
I started wiring everything up and realized i was wiring them to have 87 the fused constant +12v... so i dont want to re-wire..lol
Advice is appreciated. Thanks!
85 and 86 are not polarised, and can be wired either way. Convention is for 85 to go to the signal, and 86 to earth.
30 and 87 are likewise not polarised, and can also be wired either way (for use as an SPST relay.) It is convention for pin 30 to be the power source (with any variant,) and 87/87a to be the outputs.
Yes, you can make pin 87 your power source from a practical view - but I don't suggest it. Anyone working on it later will think that pin 30 is "always hot" and pin 87 will be "switched hot" - and when it's been reversed, accidents have a greater probability of happening.