Diode in Nav/Anchor light switch question

[mpm87]

Hello,

I know this issue has been beat to death, so I apologize in advance. I am trying to control my anchor light separately from my Nav light (currently both work at once or niether work), and I keep reading that I need to incorporate a diode or use a 6 terminal switch. My question is - What amp diode would I use?

 

[Silvertip]

Re: Diode in Nav/Anchor light switch question

any simple diode with a 1 amp or higher rating would be fine. Radio Shack is a good source for about a buck and some change.

 

[mpm87]

Re: Diode in Nav/Anchor light switch question

Thanks Silver Tip for the feedback.

On my switch, there are 3 screw terminals marked B, H, R (I'm not sure what those labels represent). Now I'm assuming that my switch is good and wired correctly to begin with (I hate to assume...). I'm not really sure how to hook up the diode since the diagram on iBoats that is posted has only 2 screw terminals. Any help or direction would be great!

 

[Silvertip]

Re: Diode in Nav/Anchor light switch question

Which diagram are talking about???? Whether a switch has screw terminals or spade terminals makes no difference. If you have a switch with only two terminals it is a single pole-single throw and cannot be used for Nav/Lights. You need a three terminal (On/Off/On) switch. Just wire it like I show in my diagram. The designations you mention are meaningless (except to who ever designed the switch). The center terminal is the +12 volt connection. The other two terminals are for the NAV (bow) and ANC (stern) light feeds. The diode has a band on one end and it may also have an arrow pointing toward it. Install the diode as shown in the diagram. Here is my diagaram again. Here is how this works. The purpose of a diode is to allow current to pass in one direction but block it in the other. Without the diode you cannot make a three terminal switch do what you need it to do unless you buy a specific Push-Pull style switch designed specifically for this purpose or unless you use a six terminal switch. The black bar with the up/down arrows on it is the internal switch mechanism that connects the various terminals. When that bar is in the up position, the center terminal feeds +12 volts to the upper post on the switch which connects to the ANC (stern) light so it turns on. The diode blocks current from flowing back to the NAV (bow light). So what you say! If the diode wasn't there it wouldn't anyway because there is no connection to the NAV light from the upper terminal. That would be a correct observation but stay tuned. So now you flip the switch so the black bar connects the +12 volt (center) terminal to the lower (NAV) terminal and it will now light. But when you are navigating (under way) BOTH the NAV and ANC lights must be on so without the diode, the NAV and ANC lights have no way of both being powered at the same time. Enter the diode. It allows current to flow TO the ANC light when the NAV position is selected. So why not just use a piece of wire you say! Well -- back to the ANC position it becomes apparent that current would then have a path back to the NAV light so BOTH would again be on and when at anchor, ONLY the ANC light is to be on. Clear as mud?? Follow the juice and it becomes perfectly clear.

 

[mpm87]

Re: Diode in Nav/Anchor light switch question

Hi Silvertip,

I understand how the diode works in this situation. I also understand the diagram posted by you above. I just don't know which screw terminal is for what on my switch if you know what I mean. Like I stated in my earlier post, I have 3 terminals marked H, B & R, not Anchor or Nav Light. I have a Cole Hersee brand M-531 3-Position Push-Pull Switch (I tried to post a picture of it, but it didn't work)
Now, I'm assuming the "H" one is for hot (or 12V)?, but I'm not sure which terminal (B & R) is for the anchor and nav light. Again, I'm assuming that the wiring is correct to begin with. Thanks for your help!

 

[PuddleJumper]

Re: Diode in Nav/Anchor light switch question

Apply 12v to middle one , if both other terminals become live in both switch positions then you have the correct one for hot. Then install diode and wire accordingly. If this isn't the case try 12v to other terminals trial and error until you get the scenario above Hope this helps

 

[Silvertip]

Re: Diode in Nav/Anchor light switch question

It would have been nice to know you had a "push-pull" switch, the manufacturer and the part number. Makes doing a Google search very easy which is where I found the information you need. This switch information indicates it is for two circuits with one switch such as nav lights so you DO NOT need a diode.

Here ya go: http://www.colehersee.com/home/item/cat/137/M-531/