that ground should be to fake the car into thinking that the parking brake is set to allow the video display. from what i can see of the button that was used in the how-to, it is not a lighted switch, just a basic dpdt switch. or in other terms, it's grounding one signal, and opening the other when the switch is activated.
Originally Posted by OldSpark
otherwise, champak, did you understand most of oldsparks post? it answers your question, though a little technical..
the whole point of using the relay+switch combo is because it is cheaper then the $50 switch, and gives you a location to connect a indicator light like you desired.
I thought it was the extra terminal for lamp power (grounding).
Now I see it is a DPDT switch.
An example of my stupidity (in this case resulting from too fast a read/look).
Thanks soundman - again.
And champak, that's 2 of us supporting relays.
If I was too technical, try me again.
But think of a relay as a "switch extension" where any small on-off switch controls the real switch that switches whatever connections and power that you need.
Too technical is an understatement lol. But like I said, I do understand the very general function of a relay, it's just a matter of understanding it's neccesity here. But if the two of you say I should use it here, I will go with the experts in this area and learn a little more.
Is the following how I should set it up?
kind of. by adding the relay, you can add the indicator light without affecting the wires coming off the headunit/car:
so whenever the relay is on, the indicator light will turn on.
That's wrong Soundman - you have the indicator in series with the coil...
Champak - paraphrasing: A switch or HU etc turns on the coil in a relay. That coil switches the relay contacts.
Soundman, I don't understand what you are indicating. It seems you changed my 6pt switch to an 8pt, and the red circle is suppose to be the relay? Changing the type of switch I have is not really an option, so if that's needed I'll be unable to do this.
OldSpark, it seems that you are saying my setup is correct?
Oh dear, already using 6pt & 8pt for a 2P relay - will that be confusing?
Not that soundman has changed the switch, only the relay. You only need an on-off (SPST) switch or 12V for a relay.
And yes Soundman - better. Thanks!
For some relay animations (click on the various animation triggers if needed, and go back or fwd for more info...), see f.ex:
HowStuffWorks - relay1
PCB Heaven- How Relays Work/
The Electronics Club - Relays
Absorb Electronics - An SPDT relay
PS - sorry Champak, I haven't followed your circuit & desires, I merely described the use of relays.
I might look later, but first I want to fix my PC... :pray:
Ohhhhhhhhh, I think I understand now.
1/ Scrap the switch I have now and get an 8pt relay(don't know the proper name).
2/ Get a simple on/off switch.
3/ When the switch is on, the elec passes through turning on the light, and at the same time activates the coils in the relay making my connection.
4/ When the switch is off, elec to the light is cut, and at the same time the coils are deactivated cutting the connections in the relay.
I just have to find one of these relays now.
I shouldn't have to get a new switch though should I? Can't I just rewire my current switch?
Exactly right. Simple isn't it...? (ONCE you know!!)
And yes, any switch. You only have to "make and break" the current/voltage that "energises" the relay's coil.
(Well done understanding that bit too. Relays usually simplify the controlling switch, but if you already have one that is suitable or fitted, why not use it? ...Unless there is a better smaller switch...)
Congrats on surviving your introduction to relays.
Next - relays if needed for better headlights, the addition of any accessory regardless of their current demand, etc etc. (Heavy current relays usually get their power from their own heavy & fused wire direct from battery+. The (small-)switch wiring determines if the relay can be on anytime or via IGN or ACC etc. And the same for loads that should have "clean" 12VDC - like audio, PCs, etc. But that's another lesson...)