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rogerdw
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Joined: 22/10/2019
Location: Australia
Posts: 938

Posted: 10:05am 12 Nov 2025

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Hi guys, there’s been a few discussions around the traps on sourcing suitable toroids to rewind for inverters and I thought it may be handy to have an up to date conversation.

Certainly the cheapest entry (here in Australia) can be had by sourcing old Aerosharp grid tie inverters … though if you are wanting to build a decent output inverter, you must aim for a 3kVA Aerosharp. They also sold a 5kVA GTI apparently, but I’ve never seen one.

Sure, their 1.0 and 2kVA inverters each have a toroid … but they are babies compared to what we want … so don’t waste your time with them (unless you’re building a Warpverter). Keep an eye out for a model HR-INV-X01-030

HR-INV-X01-020 = 2kVA and HR-INV-X01-010 = 1.0kVA … and they all look very similar

I had great success when I first started looking by searching for solar repair companies. Then I rang them and asked the question. Very first one said yes, there’s some down the back … we get $25 each for them for scrap … you can have them for $25 each. I couldn’t get there quick enough.

After picking up a few I was after another and they had run out. So I rang the next repairer on my list … and they had one for $50. Still a bargain I thought, so I grabbed that too.

I keep “Aerosharp” in my search on marketplace and see them quite often … but usually they want stupid money for them and never get sold. Still a bargain there occasionally though.

I have no idea about the US but here in Adelaide South Australia we have AEM Cores who may well be the only supplier/winder of toroid cores in the southern hemisphere.

They can wind toroids from strip up to 105mm wide, to whatever size required.

If you want one higher than that, you need to stack two together … so for 140mm high, they would wind two 70mm ones and stack them … then anneal them in the one unit.

I’m waiting for a quote on a couple sizes but it hasn’t arrived yet. One is the same size as a 3kVA Aerosharp toroid and the other about 25% bigger. I’ll post details when the quote arrives.

Of course freight will be a significant amount due to the weight, though no major problem if you can collect it.

Maybe tinyt or others might be able to give us some clue on what’s available in the US or Europe.

Cheers, Roger

rogerdw
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Joined: 22/10/2019
Location: Australia
Posts: 938

Posted: 10:10am 12 Nov 2025

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Okay, now that is out of the way, there is something else to be aware of … there are actually two different physical sizes of toroid core found in 3kVA Aerosharps.

Both have a 98mm ID and are 70mm high … but one is 190mm OD and the other 210mm OD … don’t ask me why … and one has a blue label and the other a yellow label. So ideally you’d want two the same if you’re gonna stack two of them for higher power.

If I was needing more toroids, old Aerosharps would be my preferred choice. In my experience, they have been 50-100 times easier to find than an IFLA or forklift battery … so pretty easy really. If I had plenty of dough, I might spring for new cores … but I’d have trouble going down that track knowing you can get secondhand ones cheaply.

Another big advantage is all the hardware and goodies that come with the old inverter … along with kilos of 1.6mm copper wire which can be reused and save more $ again.

The large chokes and all the big caps in my four MPPTs came from wrecked Aerosharps.

The clear mylar tape that insulates the windings can also be reused and again saves heaps of $.

Cheers, Roger

Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 1208

Posted: 01:06pm 13 Nov 2025

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I haven't seen Aerosharps around locally for years,
https://www.tortech.com.au/
Shipping for one of the ready made toroids was reasonable, but a bit small for our purpose.
Might be worth checking with them as they will make one when you enter the details in the Transformer Custom Design sheet.
https://www.tortech.com.au/custom-design/
Perhaps they can supply a bare core, worth asking.

Cheers Aaron
Off The Grid

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