2 wire tricolor/anchor circuit

[Downeaster]

Using diodes (or the LEDs themselves) you can light an anchor light and tricolor by applying +12v or -12v across two wires. Pretty clever and it is I believe fairly common on some production boats.

The diode/LED side is straightforward. Each light will only light with one polarity.

What I'm trying to figure out what this circuit looks like back at the panel. On my boat there are two switches (tri and anchor), each sending voltage down to a DIN rail and then out the two wires to the mast. How does one side serve as ground to the other since there are only two wires? Does anyone how it works? I am troubleshooting it and, without this basic knowledge, am not sure how to proceed.

Thanks for any thoughts or suggestions!

[tek-noid]

Are you saying you *have* this 2-wire LED system with two switches and want to know how it is wired?

Or that you want to *add *a 2-wire LED and manage it with your two switches?

James

[Tupaia]

It would normally be done with a 2 way toggle switch. There are 6 terminals on the switch - Incoming 12v (+/-) goes to the centre terminals and outgoing +/- on one side and -/+ on the other side.


Example:

https://www.nasamarine.com/product/s...itch-assembly/


If you used 2 switches you would have to include diodes in each switch circuit that disabled the "other" switch to prevent a short circuit. You will still need 2 way (3 terminal switches).

[Downeaster]

Thanks for the responses. It is wired already with 2 standard switches so there must be another diode or two in the panel that i need to locate.

[SailRN]

From the 12 v Doctor:



The LED is a diode.


At the time this was published the LED was unheard of. If you're using LED then replace the diode shown with the LED and remove the light represented by the circled X.

[goboatingnow]

Originally Posted by SailRN

From the 12 v Doctor:


Attachment 257353
The LED is a diode.


At the time this was published the LED was unheard of. If you're using LED then replace the diode shown with the LED and remove the light represented by the circled X.

No. Just replace the lamp shown with a led bulb of appropriate working voltage bearing in mind the polarity shown

Leave the diode as shown as the reverse breakdown voltage of most leds is very low.

[skipmac]

Originally Posted by SailRN

From the 12 v Doctor:


Attachment 257353
The LED is a diode.


At the time this was published the LED was unheard of. If you're using LED then replace the diode shown with the LED and remove the light represented by the circled X.

This is how I wired mine. Works great and I eliminated one wire to the mast when I rewired it.

[SailRN]

Originally Posted by goboatingnow

No. Just replace the lamp shown with a led bulb of appropriate working voltage bearing in mind the polarity shown

Leave the diode as shown as the reverse breakdown voltage of most leds is very low.

Good point. Check the reverse breakdown voltage of your mast LEDs, and if they're reverse polarity protected or publish reverse breakdown voltage higher than your supply voltage, only then remove the other diode to reduce voltage drop. I believe mine are reverse polarity protected by an internal diode, and do not need the external diode.

[AKA-None]

Originally Posted by skipmac

This is how I wired mine. Works great and I eliminated one wire to the mast when I rewired it.

You still need a way to turn both off
So a three position switch or a second switch to provide power

[skipmac]

Originally Posted by AKA-None

You still need a way to turn both off
So a three position switch or a second switch to provide power

Well I ended up with both. The DPDT is off in the middle, on with different polarities left and right. But I had the original masthead anchor light switch still there so ran power through that switch to feed the DPDT. So if spending a while in a harbor just leave the DPDT on anchor and switch on and off with the old switch.