Diodes in Hot Rod Lighting Circuits

Anybody ever use a diode to keep the turn signal flasher from back feeding into the other bulb through the parking light circuit??

Do you remember what diode you used?

Slide...............

 

I do. We just moved and I'll try to find the box with the part number.

 

I've used them. The best thing to do is use a "tail light converter" , go to your autoparts store and ask for a tail light converter, commonly found in the trailer/tow section.
Before you go spend your money, take a look at your ground on the turn/stop/tail light and make sure you have a good clean ground, often times if you have a poor ground you will have feed back into the tail light circuit from the turn signal circuit.

 

More often than not, when guys ask about diodes, they are adding turn signals to their car with a simple switch,,, not trying to fix a current problem.

 

IN4001 at radio shack will probably work

http://www.radioshack.com/product/index.jsp?productId=2036268

 

Although the 1n4001 would probably work, it may be a little under in the current rating department. The diode is rated at 1 amp, where as the turn signal filament on 1034/1157 bulbs is 2.1 amps. So you do the math, the diode will get hot if left on long enough. In the brake light circuit I would certainly NOT use that diode.

A better choice is the 1N5401, which is rated at 3 amps.

 

Interesting thread. I have diodes on my front parking lights.

Originally from GM they would come on with as parking lights but go off with addition of the headlamps. A one way diode from the headlights allows the parking lights to operate at all times without back feeding to the headlights when only the running lights are on (55 Chev).


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Thanks to all. I'm assuming you can parallel a couple of diodes to half the current?

This is on the front turn/parking lights.

 

You could just move the parking light wire (at headlamp switch) to the tailight terminal.

 

True, it could be done at the switch. I just put a jumper diode out at the bulb wiring when I was running all new wires forward of the firewall. It was just easy to get to while the sheetmetal was all going together.


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IN1004 is the interplanetary standard for this kind of low current application.

edit: what Squirrel said.

 

very interesting, so you say you need a diode that is rated at 400V, but only handles 1 amp of current. Think about it, the normal turn signal bulb draws 2.1 amps, the normal parking lamp draws right at 1 amp. Now if you add the two parking lamps together, you have ~2amps! The 1N4004 is not going to like that! 1N5401 is rated at 3 amps, so no problems.

 

The low current side of a turn signal relay operates on around 0.2A. If the relay is capable enough, you can stack 1157's until the end of time and that low side current won't be affected. In the case of my hooptey, I have _8_ 1157's powering my taillights (4 per side), and I'm using a standard "cube" type P&B 40A relay to drive them. The low side draw is 0.18A per my ammeter. As for ratings... I didn't say you need a 400v rating. I said the 1004 is the interplanetary standard for such things... that is, if you went to Scrap Shack or other "retail" store for diodes, you'd find that to be the most common/plentiful/cheap, rather than a very obscure 20v rated unit (because there's no reason to make a 20v rated unit when 400v units are so commonplace).

That is all.

 

Where did relays come into this thread, thought we were talking about diodes? Older vehicles do not have turn signal relays, so if using diodes for the lighting, the diodes had better have sufficient current ratings. Radiation Shack is the last place for components, would rather order from Digikey or Mouser.

 

That's not a very accurate blanket statement you are making. There are plenty of "older vehicles" (whatever that means) with relays. And nobody mentioned copper wire, batteries, light switches, etc, but we're talking about them as well if we're talking about the lighting circuits. The OP didn't say what make/model vehicle he was talking about, so your assumption that there's no relay is just as (in)valid as mine that there might be. And, of course, you should use components that are sufficient for your particular application... it's silly of you to try and intimate that I am saying otherwise. In the application that popped into my head when I read the OP (again, he didn't tell us a specific vehicle), there are relays, and a 1004 is PLENTY. Obviously, in the example that popped into your head, it's not.

Of course there are better places. It was a simple, well known reference. Are you done nickel and diming my post with red herrings?

 

Your post is history! And please take your red herrings with you! (1n4004 too!)

 

Uh, OK.

You should consider adding me to your blocked user list. That is what I am doing now for you. You should also consider finding out what a red herring is... 'cuz you're throwing them out like beads at Mardi Gras.

 

The question didnt seem that complicated.

The answer probably shouldnt be either.


But somehow, you guys are capable of fucking it all up with Drama...