Bulb Questions and Confusion - Automotive-type Bulbs

[jviss]

So, I'm confused.

First, the LED replacement bulb I bought for my anchor light, a Dr. LED Polar Star 40, mates with an 1157 socket, which is a dual contact, dual function socket. I imagine the lamps this is targeted for also have this socket. Why is that? If it's only a single function, why a dual function bulb base and socket? Could it be so that it will be indexed properly when installed?

Also, I purchased an 1157 socket at Auto Zone for debugging purposes, and it appears that the two contacts of the bulb meet the two contacts in the socket at 90º - meaning, each contact straddles both of the bulb. At least that's what it looks like to me. I could be wrong. Maybe the round socket contacts just catch the edges of the cat's eye shaped solder contacts on the bulb base. I don't know.

Does anyone know more about this?

Thanks,

jv

 

[FastOlson]

As I recall, the bulb base rotates 90 degrees when you insert and turn it into its bayonet base.

 

[jviss]

As I recall, the bulb base rotates 90 degrees when you insert and turn it into its bayonet base.

Thanks. It turns a lot less than 90º, more like 10º. (I have a bulb and socket in my my hand now.). With mine, as I rotate it after inserting the bulb, it rotates such that the bulb contacts appear to be nearly 90º to the socket contacts.

 

[ggrizzard]

"Dual Contact"!
One for the red (hot) wire contact, one for the black (or yellow) wire (ground) contact.
And yes, it doesn't turn that much to lock.

 

[jviss]

"Dual Contact"!
One for the red (hot) wire contact, one for the black (or yellow) wire (ground) contact.
And yes, it doesn't turn that much to lock.

The socket I purchased as only two wires, one to each bulb contact, which are presumably one for each filament on dual filament bulbs; the housing is the ground.

 

[FastOlson]

Thanks. It turns a lot less than 90º, more like 10º. (I have a bulb and socket in my my hand now.). With mine, as I rotate it after inserting the bulb, it rotates such that the bulb contacts appear to be nearly 90º to the socket contacts.

Well rats. I misremembered that angle! I do recall having to replace those bulbs - way too often - in cars in the 70's, and it's obviously been too long!

 

[Hollyberry]

Are the 'pins' travelling the full length of the slots?

 

[LloydB]

1157 bulb is dual filament one for running and one for stopping. Are you adding brakes? If you power both functions at the same time you will have a shorter brighter bulb life powering the dimmer running function should give you the longest bulb life. Feel grateful it's not a '58 VW

 

[jviss]

Are the 'pins' travelling the full length of the slots?

No, it's an indexed socket and bulb, one slot shorter than the other.

 

[jviss]

Here's an update. I tested two different bulbs in the socket I bought. For both, the two pins of the socket energized the bulb; the shell, or case, had apparently no connection. Neither bulb was polarity sensitive, both the Dr. LED Polar Star 40 or the "generic" one I bought on Amazon. So, to be clear, one pin positive and the other pin negative, no connection to the shell.

Polar Star 40

HQRP BAY15d Light Bulb Cool White 33LED SMD2835 compatible with Aqua Signal Series 40, 41, 42,& 50 / Hella 2984 and Perko 200 Fixtures 10-30V DC Replacement

I must say, the latter is pretty bright! But, I am pretty sure it's not certified for nav use, as is the Dr. LED. $45 vs. $12. Yikes!

By the way, it seems whoever wired my mast scrambled the wires for the fancy, mast-top fixture that houses strobe, tri-color, and anchor light. The wires from the boat to the masthead fixture, an Aqua Signal Series 40 tri-color anchor/strobe navigation light, are blue, yellow, and purple, respectively; the connections to the mast to make it work properly are purple, blue, and yellow. I guess whoever installed the light messed it up. So frustrating! This fall when we pull the stick I will sort it out.

 

[Jim Legere]

So, I'm confused.

First, the LED replacement bulb I bought for my anchor light, a Dr. LED Polar Star 40, mates with an 1157 socket, which is a dual contact, dual function socket. I imagine the lamps this is targeted for also have this socket. Why is that? If it's only a single function, why a dual function bulb base and socket? Could it be so that it will be indexed properly when installed?

Also, I purchased an 1157 socket at Auto Zone for debugging purposes, and it appears that the two contacts of the bulb meet the two contacts in the socket at 90º - meaning, each contact straddles both of the bulb. At least that's what it looks like to me. I could be wrong. Maybe the round socket contacts just catch the edges of the cat's eye shaped solder contacts on the bulb base. I don't know.

Does anyone know more about this?

Thanks,

jv

The "DC" (Double or dual contact) bulb has been a marine standard for years. An 1157 automotive socket is for combined brake and tail lights. Different design briefs.
"DOUBLE CONTACT INDEX BULBS are made with a heavy duty glass envelope for break resistance. Nickel-plated brass bases prevent corrosion while insuring a positive point-of-contact. Filaments, with "rough service" design, permit hours of reliable burning. These incandescent "indexed" bulbs have pins are at different heights, so the bulb (and filament) orient in a specific direction within the socket and fixture. This ensures that they meet visibility requirements when used in navigation light fixtures. "

 

[jviss]

The "DC" (Double or dual contact) bulb has been a marine standard for years. An 1157 automotive socket is for combined brake and tail lights. Different design briefs.
"DOUBLE CONTACT INDEX BULBS are made with a heavy duty glass envelope for break resistance. Nickel-plated brass bases prevent corrosion while insuring a positive point-of-contact. Filaments, with "rough service" design, permit hours of reliable burning. These incandescent "indexed" bulbs have pins are at different heights, so the bulb (and filament) orient in a specific direction within the socket and fixture. This ensures that they meet visibility requirements when used in navigation light fixtures. "

Thanks. Where did you quote that from?

Note from my post #10, although these use a dual contact, polarized socket, they are not dual filament bulbs. And, they are wired differently than the automotive application.

 

[Jim Legere]

Thanks. Where did you quote that from?

Note from my post #10, although these use a dual contact, polarized socket, they are not dual filament bulbs. And, they are wired differently than the automotive application.

Anyone who has used Aqua Signal or Perko incandescent running lights should be familiar with DC bulbs. Rather than write out an explanation myself, I found this after just a quick search: DOUBLE CONTACT INDEX BULBS