[TriEmbed] Inexpensive 120V (15A) to 240V (7.5A) transformer?

Josh Wyatt dragojdw at gmail.com
Tue Apr 12 05:45:31 CDT 2016


What are your power requirements?

A few ideas...

1. If all you need is high voltage DC for charging a battery bank, you
could use a voltage doubler. Check out the full wave circuit here:
http://www.daenotes.com/electronics/devices-circuits/voltage-multipler

2. You could buy two identical 120vac-to-12vac transformers and use one for
boost. Connect transformer 1 in the conventional way, to provide 12vac.
Connect the 12vac output of transformer 1 to the 12vac winding of
transformer 2; the "output" of transformer 2 will now have 120vac which you
can place in series with your line voltage for 240vac. (make sure it's in
phase or you'll get 0 volts out).

3. Alternatively, search ebay for 'control transformer,' as this is a
pretty common need and application in the electrical world. Be sure to
choose it properly for the voltages and power you expect. For example,
http://www.ebay.com/itm/Square-D-9070T150D1-Industrial-Control-Transformer-SCHNEIDER-ELECTRIC-/272208984055

Lastly - It goes without saying, but be careful; you're dealing with lethal
voltages here.

Thanks,
Josh

On Mon, Apr 11, 2016 at 11:14 PM, Kevin Schilf via TriEmbed <
triembed at triembed.org> wrote:

> Hi Phil,
>
> I don't know what Shane has in mind, but that is an interesting idea about
> using two receptacles; although, Mr. Murphy will probably ensure that
> opposite phase receptacles will be several feet apart as you note.  :-)
>
> Why not just add a two pole, 240V circuit breaker assuming you have space
> in the panel and can reasonably run wire from your load to the panel?
>
> BTW, I think there may be a typo in your email, should be:
>
> AWG 10 -> 30 A
> AWG 12 -> 20 A
> AWG 14 -> 15 A
>
> To anyone reading this post, same impedance at twice the voltage = 4 times
> the power delivered.  Please be careful and consult a licensed electrician
> if in doubt.
>
> Sincerely,
> Kevin Schilf
>
> ------------------------------
> *From:* Phil Smith via TriEmbed <triembed at triembed.org>
> *To:* Shane Trent <shanedtrent at gmail.com>; TriEmbed Discussion <
> triembed at triembed.org>
> *Sent:* Monday, April 11, 2016 6:59 PM
> *Subject:* Re: [TriEmbed] Inexpensive 120V (15A) to 240V (7.5A)
> transformer?
>
> If you can find outlets close to each other whose hots (x and y) are from
> adjacent circuit breakers, then you could combine x,y, and g (ground) using
> two plugs to get 240V, although the outlets are likely only rated at 120V,
> 15A (14 AWG wire).  Another way of looking at it is x=+120V, y=-120V
> (relative to Neutral n here n ~= g except at high current draw.  Often
> wiring within a single residential room is from a single circuit breaker.
> Interestingly, the National Electric Code (NEC) rates 10, 12, and 14 AWG
> wire at 15,20, and 30 amps no matter how long the wire is, analogous to the
> state of SC once legisilating the value of pi to be exactly three.  AWG<10
> wire is not subject to this arbitrary amperage and equations for resistance
> and reactance are used instead.
>
> Phil
>
>
> On Monday, April 11, 2016 5:16 PM, Shane Trent via TriEmbed <
> triembed at triembed.org> wrote:
>
>
> Hey all!
>
> I am looking for a transformer to setup 120V up to 240V. I recall seeing a
> transformer company at the Hamfest last year but do not remember the name.
> Can anyone recommend a vendor? Does not have to be a high-end design. Is
> powering a charging system that corrects for variations in line voltage.
>
> Thanks for any suggestions!
>
> Shane
>
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