12vdc to 12vac and 9vac

[sageauk]

I have this 2.1 speaker that i want to use with a 12v battery. I do not want to use an inverter.

The transformer gets in 240vac and gives out 9vac on the white wires and 12vac on some red wires. The circuitry then gives our some other dofferent outputs

Is there a way I could make the 12vdc to 12vac and 9vac (schematic)

I dont want to step up the 12v to inject it as 240v again

Your Help is highly appreciated

 

[alec_t]

Is there a way I could make the 12vdc to 12vac

Firstly, why? Your transformer already provides 12VAC.
Secondly, the obvious way for you to get your 12VAC from 12VDC is to use an inverter. Why are you reluctant to use one?
Thirdly, have you checked the related threads listed at the bottom of this page?

 

[Reloadron]

What it sounds like you have is a set of 2.1 line powered speakers. What you need to do is get a little beyond where you left off and look closely at the power supply inside the unit. Most speakers like this that are low power take the incoming AC and rectify it to DC. If these are low power the solution may be as simple as a 12 volt battery and a small 9 volt regulator. You need to do a better job of seeing what is in there.

<EDIT>Alec is quick, knew I should not have turned to chat with wife! </EDIT>

Ron

 

[sageauk]

Thanks. I should have thought better. looking for the 2 rectifiers and injecting the dc from there.
Thanks

 

[sageauk]

Thanks Reloadron. I should have thought better. looking for the 2 rectifiers and injecting the dc from there.
Thanks

 

[Reloadron]

Let us know what you find (where the AC in goes) and if possible pictures are a nice touch if you need more help.

Ron

 

[sageauk]

I am Giving up. The 5 wires from the transformer the white ones emitting 9vac and going to the front panel. the 3 (2xred, 1x black) are acting funny to me. If you use the black (middle) as a common the two reds are showing around 16vac on the voltmeter. if you measure the two reds they giving around 30vac. Those are the ones that are being rectified as you see in the image and the black seems to run everywhere. Once rectified measuring on the shown points the voltmeter read around 45vdc

I am now going to do an inverter though i was running from that fact.

**broken link removed**
**broken link removed**

 

[micr0man]

It would seem you have a centre tapped transformer. This means you get 12v-0v-12v. If you rectify the two red wires you will get 24v. Your black wire is your ground (or 0v) so in relation to that you will get -12vDC and +12vDC after the rectification. This is used in amplifiers to allow the output to swing both above and below 0v. This means to get you amp to work you would need 2 12 v batteries in series. Neg of battery 1 to -12v, positive of battery 1 to 0v and negative of battery 2, positive of battery two to +12v. I hope that made sence,

Dave