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Cathodes on when doors open

I am trying to wire some cathodes on a on/off/on switch. i want them to come on when it is in one on position so i am just wiring that straight from the batter, but i also want them to come on when my doors open. How would i do this? would i just get access to one of the wires after the pressure switch in the door, and tap the wire leaving it? or do i need a relay? and if so how big of a relay? the cathodes pull about 1 amp

Is this some kind of rust prevention system?

I know about anodes in the boat. Interesting effect.
Now you have me thinking was that also cathodes in the bottom of a boat?

I’m not sure how you do this, but it seems like a relay will save you from potentially frying the door light circuit. Lots of those lights go through a simple microprocessor circuit now to allow the delay and slow dimming off when you close the door.

Use a relay.

Battery to one side of the relay’s coil, other side to both your switch and to your door switch. Put a diode in the line between the coil and the door switch or your new switch will also operate your interior lights.

Battery to one of the relay contacts, other contact to your load (cathode).

thanks jay, i kinda understand but kinda dont, could u draw me a schematic?

The relay has 4 connections. Two are for the coil and control the other 2, which are the contacts. Put a voltage on the coil and it switches the relay on, like turning on a switch.

Battery positive to connection one of the relay’s coil.
Other side (connection 2)of the coil to your switch.
Other contact of your switch to ground.

Another wire from connection 2 of the coil to the positive side of a diode.
Negative side of the diode to your door switch.

Battery to relay contact 1.
Relay contact 2 to your cathode positive.
Cathode negative to ground.

Fuses in both wires from the battery unless you like electrical fires.

Now draw this as I’ve described, drawing one sentence at a time. You’ve drawn your own scematic.

wow, ya i totally dont get that, is there an easier way?

Why Exactly Are You Doing This? Maybe Somebody Can Help You.

JayWB’s description should have done it. He was specific and clear. You may be over your head. Tell us what you’re trying to accomplish with the cathode installation and maybe JayWB or somebody has a way for you to get it done. What are the cathodes going to do for you and where do you want them to go?

If it is an anti rust system, it is likely not needed in any modern car as they are far more rust resistant than older cars were.

I will add that the usual systems don't do much to protect the car. They often get credited with doing well, when in reality it is the car's design not the add on system.  

If your system does not have a ground (like a chain dragging on the ground) it likely is dong nothing of value for you.  Those rubber tyres insulate the car so those systems can't work.

so i reread jays post and ur right it did do it. yesterday i just couldnt wrap my head around it for some reason. joseph cathodes r lights. i want them to go under the dash and come on when the doors open but also be able to turn them on whenever iw ant.

ok… now that i have researched these i understand.

these are the ‘ground effects’ lights you may see on cars. typically a blue or green light showing on the ground under, around and beneath cars.

what i am finding is they are 110 v. you need to get a 12 volt inverter to make 110 volts in the car. IMHO this is a huge waste of money and time, but hey… to each his own.

you could use a relay piggy backing off the door switch to energize this system, but again, i am sure the auto specialty stores would be able to help you figure this out. (especially if you were buying the stuff from them.)

I apparently need to get out more. I know what a cathode is, I can even give you the entire technical dissertation on the term, but I’m completely bewildered about this “wiring a cathode to the on/off switch” thing.

Can anybody out there clarify this?

I am thinkin one line switched and fused from the battery, and a second line from the line after the door switch (assuming it is positive)ie hot when the door is open with a relay, to the other side of the switch from the battery lead. that gives 4 conditions.
switch off door closed no lights
switch on door closed lights
switch on door open lights
switch off door open lights.

i believe these are neon. they need 110 v ballast to operate.

bman11 do you have a job to pay for this stuff?

and do you pay for ALL the costs for your car? payments? insurance? registration?

if you have any extra cash left why would you want to spend it on something that does not improve fuel economy, or cut the expense of operating your car?

have you read the paper lately? the economy. jobs being cut. no work. companies laying off thousands of workers.

or did you find a way to get some bailout cash? (if so, please share the info so we can be so enriched)

p.s. tjscott where r u?

I made the assumption they were 12 volt ± dc due to his thought of wiring it to the battery, Hey the floating light makers need to make a living too! Might be a kid livin with the folks with nothin but disposable income, or perhaps he’s a banker, there was a story yesterday about a bank that got bailout money and now taking 100 emplyees to Puerto Rico for a $400 a night hotel reward, saying we are not using bailout money to do this, nothin but crooks and con men, let the guy have his lights and go after the big fish!

I am sure glad that you gentlemen got involved ith this. I read it last night and decided it was best left alone.

Thank you again.

If the OP called them “neon lights” instead of “cathodes” I could have given a detailed answer in Spanish which would have much easier for him to understand…

wow thanks for ur input cappy lawl, yes i make all paymence for my car and im 20. and its not a beater either its an 05 civic thank u very much. and here in canada the economy isnt as bad as u yanks (just assuming htats where u r, sorry if not) and yes i have a job. and last of all, u can buy cathodes from a computer store for like 10 bucks, they come with a transformer. thanks so much for ur reply