Switch + Relay Possible

**dcpyatt** · 10-27-2009, 01:23 PM

I think that I have exactly what you are wanting to do... I made it back in 2000 when I was running my MP3 box in my car.

It is a self keeping relay, triggered by a push switch with a toggle switch for the primary power switch. It basically was a relay and an SCR. I will have to see if I can pull it out of the car and get a schematic and pics from it.

DaveP in Ohio
dcpyatt@jclay.com

**Bugbyte** · 10-27-2009, 04:56 PM

Originally Posted by atrixstars

I cannot do that. My ground pin is for the 'led' ground.

Here is a diagram for switch:

Pin 1 to a +12 wire
Pin 2 to your electrical device
pin 3 (brass) to earth/ground for led.

Ah! In that case, you are okay.

**soundman98** · 10-27-2009, 05:19 PM

lol, i almost didn't catch that ground on the switch...

everything looks good except that you are missing a powered line to 30 on the relay.

the way that you have it in the diagram, the devices hooked up will only stay off if the switch is off, or power on/off with the car if the switch is on. there is nothing in the diagram to keep the console on when the car is off-- you will either need a double throw, single pole switch, or will need to use 2 switches.

**GizmoQ** · 10-28-2009, 12:19 AM

I changed to two relays so the switch only needs a low current always on 12V battery line into the center pin. The two outer pins go to each relay's pin 30.(diodes did go inline each relay's pin 87a to prevent power going across fronone relay to the other) One relay has power all the time coming from my distribution block fed directly off the battery and the other is a high current ACC line fed from the main fusebox. This way when the switch is OFF neither relay is energized ever(even with the car running). With the switch in the ON position, the relay connected to the battery is energized an the PC is on all the time. With the switch in the AUTO position the PC is power via the high current ACC line and it comes on when the car is on and when the ignition is turned off it goes off, too.

Like I said above, this was done to reduce the current flowing thru the switch. As a side benefit, it also significantly reduced the RFI noise seeping in through the power line, keeps the switch from failing, and allows me to use the switch for more than one powered system. I found this method to be the most effective, safe, and reliable master power switch configuration for the automotive environment.

**atrixstars** · 10-29-2009, 04:21 AM

Originally Posted by soundman98

lol, i almost didn't catch that ground on the switch...

everything looks good except that you are missing a powered line to 30 on the relay.

the way that you have it in the diagram, the devices hooked up will only stay off if the switch is off, or power on/off with the car if the switch is on. there is nothing in the diagram to keep the console on when the car is off-- you will either need a double throw, single pole switch, or will need to use 2 switches.

thanks everyone for the replies. I understand I am missing the +12 from car batt to 30.

(Short: Version) - Last Question - Read this
So if I add car battery to terminal 30, when powering it will either the pin 87 or 87a be giving me alot of power to flicker the relay? Another word safe?

(Long Version): I dont think I need to get a dtdp switch since I already purchased like many of the led stsp switches already. My main concern is, if getting power from acc or +12 car batt will there be alot of power transferring to the terminal 87 or 87a (when car off)? These switches are not for 'powering-up' the equipments but just to turn it on. I dont want it to fried or blow anything in between by giving it power. I just finish all my wiring yesterday and just figuring out how should I wired the relays+switches. However I get used two relays but really see no benefit.

**soundman98** · 10-29-2009, 10:33 AM

as long as you have 2 spst switches, and one relay, you can make it work fine:

the goal is that the switchs make the relay work-- the relay is a low draw, so it won't hurt the switches

a maybe a horribly drawn pic will help?:

this way, the switches control the relay-- one switch is to allow the csystem to turn on with the car, the other switch is to keep the system on when the car is off.

the diodes are placed after the switch(they can also be placed before the switches) to keep voltage from going backwards on one of the lines and powering anything more than the relay

**atrixstars** · 10-29-2009, 10:49 PM

thanks, for the information. That is what I was thinking of but the lines from relay to switches. I think your way sounds better. I plan on using four switches. two with inverter and two for console or pc.

**audiophyle_247** · 11-02-2009, 12:27 AM

Wow, you guys are making this much more complicated than it needs to be. lol

Here is how I would do it, and keep it very simple.

Fused power to either 30 or 87 on the relay, then the opposite to the gaming console

Run the +12v Ignition wire to terminal 85
Run a wire from chassis ground to a simple toggle switch, then from the switch to terminal 86 on the relay.

Thats it.
Key on, switch on, game on.
Key on, switch off, game off.
Key off, switch on, game off.
Key off, switch off, everything off. lol

**soundman98** · 11-02-2009, 11:22 AM

Originally Posted by audiophyle_247

Wow, you guys are making this much more complicated than it needs to be. lol

Here is how I would do it, and keep it very simple.

Fused power to either 30 or 87 on the relay, then the opposite to the gaming console

Run the +12v Ignition wire to terminal 85
Run a wire from chassis ground to a simple toggle switch, then from the switch to terminal 86 on the relay.

Thats it.
Key on, switch on, game on.
Key on, switch off, game off.
Key off, switch on, game off.
Key off, switch off, everything off. lol

it would have been alot easier this way, but he also wanted the option to turn the game system on when the car is off, and also have the option to have the game system turn on and off with the car-- hence the complexity...
(i don't blame him though-- i setup my car with a similar circuit so i don't always need my keys to mess with my carpc, or to keep it off on very short trips)