HHP

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The title pretty much says it all...

Do I really need two transformers, or can I get away with just two of the adjustable power supplies?

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l3asturd

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You just need to provide either 5VDC, 9VDC, or 12VDC (depending on which model meters you buy) to the meters. Kal's doorbell transformers reduce 120VAC to 12VAC and they are easy to procure. Then the adjustable power supplies convert the 12VAC to whatever DC voltage required, from 2.5VDC to 27VDC.

You could of course use your own power supply. If you bought a 5A 12VDC power supply and made sure you bought the 12VDC version of those panel meters you don't need the doorbell transformers.
Here is an example of a 220VAC 5A 12VDC power supply on ebay for just over $10: LINK You'd still need 2 of them though to isolate the meters per Kal's instructions.

Here's the other issue: Kal provides detailed instructions on how to wire everything up. If you buy something that he doesn't recommend, I wouldn't anticipate finding much information on how to wire your device. Although it is fairly simple. You hook up 220V to the AC input and you hook a meter up to the DC output.

As a last note, you could either ditch the meters altogether, since they aren't required for anything, or you could buy an all-in-one power meter like I did and ditch the power supplies and transformers altogether. The power meter itself is huge, but not much bigger than both of the smaller meters combined. The power meter is 96MMx96MM as opposed to roughly 79MM by 84MM combined area of the 2 meters. The big difference is the depth of the power meter is 80MM as opposed to the 24MM of Kal's meter recommendation. This wasn't an issue for me because my panel was huge, but it may be a problem for people who have their panel already planned out. Here's a picture of my panel with the power meter installed and on:

summerofgeorge

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If you're not set on using the Kal meters, you could go with the ones burglar used in his build. He references them here: http://www.homebrewtalk.com/f170/if-i-do-again-forget-amp-volt-meters-247852/#post2972097.

The volt meter doesn't need a separate power supply. He also tapped into his timer to power the amp meter. I can't verify that this setup works but this is what I'll be trying. It will save on having to deal with the transformers/power supply. I think it's about $8 for the volt meter and $20 for the amp meter on ebay.

hrafnkell

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L3asturd, thats a fancy looking meter, where'd you get it?

HHP

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I have the meters, and they are installed in my panel, I'm just finally getting around to hooking them up.

I just dont want to put another doorbell transformer in my panel if I dont have to. His website says that if you hook them both up to the same 5v source you will blow them out. Is this verified by someone other than him? I fail to see the reason this would happen...

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itsme6582

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It's plausible. Putting them in series could push more current than they are designed for.

P-J

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Kal said it. I really think you should believe him. I understand that he blew 2 of them out because of the issue.

How about asking him to explain?

l3asturd

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Yup, as I said, Kal has done his homework. He says they must be isolated, and I believe him. You should to.

l3asturd

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search for HB416PVA on ebay.

HHP

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After emailing Kal, who doesn't remember what phenomena caused the need for two circuits for the two meters, I think I'm going to try it. He said he knows that at the very least two DC power supplies are required as with only one he blew both meters.

I think that two separate DC power supplies will be sufficient isolation for the meters to not blow.

Anyone care to weigh in?

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Texas is awesome.