# How to make your own Galvanic Isolator for under $20



## yandina (Aug 29, 2000)

Check out the DIY article at

http://www.yandina.com/galvanicIsolator.htm


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## OPossumTX (Jul 12, 2011)

This one doesn't seem to be working anymore. Does anyone have a working link to a DIY isolator?


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## trantor12020 (Mar 11, 2006)

Would this be what you're looking for?

Tried uploading from home. Still unable to upload. Wonder why. File is jpg, small in size and pixel (within spec). Too bad. I can email the circuit diagram in pdf or jpg if you want. just PM me your email.


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## SlowButSteady (Feb 17, 2010)

The Yandina page works for me.


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## hellosailor (Apr 11, 2006)

The Yandina page "works" but no longer contains any diagram for a DIY version as far as I can see. However, the second page of the Yandina isolator "manual" shows it very clearly:
www.yandina.com/acrobats/GalvOwnManual.pdf

Four diodes, inserted in the ground line of a 3-wire AC connection.

|---->--->----|
|----<---<----|

Two diodes in each string, the two strings connected head-to-tail, with the ground line split and now connected to each side (left/right) of the four diodes.

I'm assuming they are using 0.6v diodes and stacking them for a 1.2v total isolation in each direction. You'd need diodes rated for 150-200v to be safely used in 120v lines.


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## boatpoker (Jul 21, 2008)

Yandina states that a capacitor in the isolator is a controvertial subject and that they are "optional" in ABYC Standards. That is not the case, they are not optional.


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## hellosailor (Apr 11, 2006)

"Yandina states"
Acutally no, Yandina stated. past tense, some time ago. The ABYC standards do change from time to time, you'd have to compare the dates.


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## boatpoker (Jul 21, 2008)

hellosailor said:


> "Yandina states"
> Acutally no, Yandina stated. past tense, some time ago. The ABYC standards do change from time to time, you'd have to compare the dates.


Still on their website.


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## Maine Sail (Jan 6, 2003)

The current Yandina GI's do not meet the ABYC requirements for galvanic Isolators. I give Yandina credit for being HONEST with customers. This is more than I can say for many other companies such as Excel water heaters, who intentionally mislead customers....

To meet ABYC standards GI's must be of the "fail safe" type or have "idiot lights" that let you know the diodes and your SHIPS ground wire are still intact. 

ProMariner, DEI Marine & Guest all make fail safe GI's... 

Many, many, many GI's have blown over the years and left vessels without a safety ground.. This is BAD...!! Due to these failures the ABYC requirements changed and this is why they now must be either "Fail Safe" or have lights that let you know they are still operable. Fail Safe GI's will not fail with an open circuit. When or if they do fail they keep your ships ground intact. They are a lot more costly to produce but are much safer because they retain safety ground in the event of a failure rather than dropping the ground altogether......

As a boat owner you don't have to "comply" but how would you feel in a Electric Shock Drowning (ESD) or electrocution case if it were your boat that caused it....?


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## hellosailor (Apr 11, 2006)

poker, their last manual for the isolator is dated 2005. 

Don't mistake anything on the internet as being up-to-date, dead pages, legacy pages, forgotten pages, endure until servers go unpaid and shut down. And then, the internet archives still keep them alive forever.

It would be nice if they could update everything or if every web page was dated, but AFAIK their description can't be assumed to be any more current than the last manual, making ABYC 2005 the target to compare it to. But that's OK too. Since ABYC, like many technical standards groups, chooses to make their standards too expensive for the average reader to ever see them, "hoisted on their own petard" comes to mind.

Failsafes, idiot lights...I still believe what Edison said, that that AC electricity stuff is going to just climb right out of the sockets and kill everyone in the room at night. We could be just as safe as the Romans were, with lead water pipes. Hmmmm.....


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## Waltthesalt (Sep 22, 2009)

I made my own, used plans on I found on the web. Works well, need to build it so that it can handle full system current flow thru the ground circuit... not likely to happen but it could. I used diode bridges... you don't use all the taps; as diodes have to be able to handle full current they're heavy duty so I bought them from an electronics supplier on line; made two duplicate parallel circuits so if one fails the other remains there; have to have heat dissipation for full current flow thru the diodes so I used spaced aluminum bars. You need to periodically check the breakdown voltage to see if the diode's failed


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## boatpoker (Jul 21, 2008)

hellosailor said:


> poker, their last manual for the isolator is dated 2005.
> 
> Don't mistake anything on the internet as being up-to-date, dead pages, legacy pages, forgotten pages, endure until servers go unpaid and shut down. And then, the internet archives still keep them alive forever.
> 
> ...


Education is expensive. The unfortunate thing (as witnessed in this thread) is that people see this stuff on line and trust it as being current and correct.


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## hellosailor (Apr 11, 2006)

Walt, couldn't you add a piezo squealer or buzzer inline with the diode bridges, so that if a diode failed and full voltage flowed, you'd get an audible alarm?


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## SlowButSteady (Feb 17, 2010)

hellosailor said:


> Walt, couldn't you add a piezo squealer or buzzer inline with the diode bridges, so that if a diode failed and full voltage flowed, you'd get an audible alarm?


Since we're talking about the ground wire, there shouldn't be any "flow" unless there is a problem (short, et cetera). As such, your alarm might not go off until there was a fault in the system. Ideally, I would think, one would want to know that there was a problem with the grounding of the boat BEFORE it was needed.


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## hellosailor (Apr 11, 2006)

"Since we're talking about the ground wire, there shouldn't be any "flow" unless there is a problem"
Woulda coulda shoulda? There often are ground problems in shore power, due to old cheap marina wiring, if nothing else. Nice concrete floating docks with little Disney castle lighted power posts and whatnot haven't quite crowded out the old "Bob wired up our docks, but he's retired now".
I never thought to ask, but those little $5 three-LED "power fault" diagnostic plugs? I wonder _how much _voltage it takes before they light up to show a ground fault?


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