Call for AC Adapters

I’ve had a good 230V pure-sine inverter for awhile now, and have used it to determine phase shift at 50Hz for quite a few CTs. After the initial round of testing, I found that both the popular VTs and CTs increased phase lead by a similar amount when going from 60Hz to 50Hz. My conclusion relative to phase shift at that time, and still is, that since IoTaWatt corrects for net phase difference, it’s better to just leave the 60Hz factors. There are some mismatch scenarios where it may be better to have two sets of phase corrections, but that is for another day.

I bring this up because I’ve taken a closer look at voltage calibration, and that also seems to be affected by frequency. It’s not a big deal, and IoTaWatt allows users to fine tune their voltage calibration, but the old calibration determined at 240V 60Hz was a little high at 20.69. I’ve changed it to 20.51, which is about a 0.8% difference. Users who have not calibrated their UK adapters might want to change their units to the new value.

Following through on this topic, many folks have benefited from this project, and if you are inclined to give back, I’d like to get samples of the various AC adapters being used, especially in the 230V countries, so I can add them to the tables with tested calibration and phase correction. I don’t even have the Euro and Australian models sold by OEM, yet they are in the tables with WAGs. There is also a popular model local to Australia that I would like to add in.

So if you are inclined to contribute to the project, consider sending me one of these international AC reference transformers. You can PM me with the model you have, and if I don’t have one, I’ll reply with the USA address to send it to.

Thanks to all for your support.


Hi Bob, I think the AU VT model you refer to is

Jaycar are 1 of 2 remaining retail electronics retailers in AU and consequently charge for the privilege. AC-AC adapters are getting rare. If you don’t have one of these, I’ll see if I can source one for you.

If anyone in AU is reading this, they have a special on a discontinued model for $10 as 1/11/18.


Thanks Tony,
That’s a pricey item. If you score one, PM me and I’ll give you my address.

My thoughts exactly - I should have checked the Altronics site (other local retailer) - About $18 there but they don’t have a store within easy access and it wouldn’t be hard to spend $10 in fuel for the trip. Your nemesis (ROTFL) :sweat_smile::sweat_smile: Pete/@BlueTardis is running one of the Jaycar ones.

The problem with the Chinese sites is you become a real scrooge as you see an Arduino Uno on Jaycar for $30 knowing full well it can be had on Banggood (or DX or any other CH site) for $5- and therefore object to a 600% mark up.


Bob are you in the UK?
Im heading to London soon and could bring some adapters if you have not had any sent yet.

PM me if interested.

How are we going for getting an AU VT across to Bob?
I’ve just ordered an IoTaWatt for use in Sydney, AU and am looking for a VT to buy locally.

The two I’ve seen mentioned here that are readily available locally are:

The good thing about the Jaycar one is that they seem to be fairly well stocked across a several of their stores, so should be easy to pick up.

I’ve never heard of Radio Parts before now but their unit has the correct, hardwired plug on the low voltage side. It is slightly smaller and has a more detailed datasheet available. Shipping from Melbourne to Sydney is $10.

Whilst writing this post, I’ve convinced myself that I prefer the Radio Parts VT and have just purchased two. If one hasn’t already been sent to Bob, I’ll send the second one across.

Got the order Kent. Thanks. It does look as if the jaycar comes with a set of adapter plugs, so equal on that front. Price looks better for the radio parts. But the real metric for these things is weight, and it has conflicting attributes. Heavier means it costs more to ship. But phase-shift is generally inversely proportional to weight. That’s why I don’t just use some 500ma unit, which would be very cheap.

I should have some euro plug units in stock by the end of the month. I bought a universal power strip on Amazon the other day with three outlets and an Aus plug (which I cut off and replaced with a US 240V plug). Anyway, with one of those, you could use the Euro AC adapter and my universal voltage USB power supply. The rig is pretty secure and would require only one receptacle near the IoTaWatt.

Thanks for the reply. Has anyone sent you over a VT? If not I’ll send some over.
Also, if there is anything else that could be of use, let me know and I’ll ship it at the same time…

1 Like

I don’t yet have any of the available local Australian adapters, so please do. Additional would be any additional CTs that you would like included in the tables. I need at least two samples (of CTs) to include in the official tables. I will do a VT with one.


IoTaWatt, Inc.
PO Box 1679
Wolfeboro, NH USA

OK, I’ll send one of each over to assist fellow Aussies who find it easier to get to a Jaycar, however I’ll be using the Radio Parts unit instead.

As for the CTs, the ones on the IoTaWatt store seem to be perfectly fine, so I’ll stick with them.

I was going to send them via TNT (who I believe are Fedex over in the US) - will I be able to ship to the PO box, or is there another address I should use?

Yes, the 50A CTs are very popular.

I PMd the street address, thanks

Thanks. I’ll get them shipped off as soon as the Radio Parts units arrive. I stopped into Jaycar this morning and picked up:

It by weight it seems to have an identical core to the 12V model, I presume with just a few less turns.
It is a few dollars cheaper and in keeping with the 9V on the other units you supply.

1 Like

I had started to look into cost to send a plug pack in the future, nice work that someone else was willing to send as well…

I use the Radio Parts powerpack

Have you looked at Australia Post International Parcel?

Standard trackable up to 500g is $24 and up to 1kg is $37.70

And says around 7 days.

Im not sure what TNT is like price wise though.

In fact, I’d like to contribute to the postage cost, up to the $37.70 based on Aussie Post, PM me either PayID or bank details once sent and I’ll deposit.

1 Like

@mobile0408 All good, the adaptors have been shipped to @overeasy and according to the tracking should arrive in the next day or two.

Perfect timing as my Iotawatt unit should be delivered in Sydney today or tomorrow too. Looking forward to getting this all running over the Christmas break.

Cheers. Up to you, the offer is there. Thanks for sending @overeasy the adaptors. He has made a great product.

Received the two VTs today in good order. Will calibrate, add to the tables, and publish the results here. Thanks, this will help increase access to IoTaWatt full capabilities in Australia.