# 12 Vdc to 10 Vac and 5 Vac

Discussion in 'The Projects Forum' started by worldHello, Oct 15, 2014.

1. ### worldHello Thread Starter New Member

Oct 15, 2014
23
0
So I need to have two inverters.
The first one is 12 Vdc to 10 Vac
the second one is 12 Vdc to 5 Vac.

How can this be done?

I found a website that introduces inversion http://homemadecircuitsandschematics.blogspot.com/2013/10/pure-sine-wave-inverter-circuit-using.html , but it doesn't seem suitable for my project.

And I thought about buying inverters instead of building one, but most inverters one can buy are 12 Vdc to 110 Vac. Most transformers are 12 V to 6 V not 5 V or 10 V. How can this be done? Do I have to build it myself?

Thank you

2. ### wayneh Expert

Sep 9, 2010
12,388
3,244
What do you want to power with those inverters and how much power do they need? If they can use a square wave, it's simple. If they need a sine wave, that's different.

3. ### ronv AAC Fanatic!

Nov 12, 2008
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How much current?

4. ### worldHello Thread Starter New Member

Oct 15, 2014
23
0
The power should be 2W-10W, and this should be a sine wave. Any ideas? Please.

5. ### worldHello Thread Starter New Member

Oct 15, 2014
23
0
Could you tell me your idea of making it a square wave? I have been searching around using Google, and my conclusion is CD 4047 Chip can make a square wave. Afterwards, use a few NE 555 chips can make that a sine wave. However, I haven't implemented this, so I don't know how good this approach is.

I would like to hear your approach, too. Thank you.

6. ### MrChips Moderator

Oct 2, 2009
12,635
3,454
You really ought to say what you are powering with 10VAC and 5VAC, at what frequency and what amperage for each.

You may want to consider a linear power amp such as LM675 or LM1875.

7. ### worldHello Thread Starter New Member

Oct 15, 2014
23
0
Thank you very much. It is a project, so I'm not really powering anything. The requirement only states 2W - 10 W. Frequency and amperage are not specified.
However, the requirement comes in when looking at the equation for power P = I*V*cos(phi), where phi is the phase shift. Any more suggestions?
Thank you for the suggestions LM675/LM1875.

8. ### wayneh Expert

Sep 9, 2010
12,388
3,244
Worst case is you need 2A at 5V to get 10W, or 1A at 10V. If you don't mind a square wave, then all you'd need is a square wave generator driving a push-pull amplifier. You can make a square wave with an op-amp, or a 555, or many other ways. Just about any "power" MOSFETs can handle switching 2A. I have a handful of IRF540N (old, easy to find, cheap) that I would use for this but there are many other options.

You could reach frequencies up to high-audio or even ~100kHz without much trouble with this simple approach. If you need higher frequencies, the design becomes more specialized.

Modern DC-AC inverters improve on a square wave by adding a brief step at zero volts in between the peaks to positive or to negative. This begins to look more like a sine wave. The more steps you add, the smaller the error becomes.

9. ### worldHello Thread Starter New Member

Oct 15, 2014
23
0
Thank you. Could you say more about the push-pull amplifier? Are you saying we can use a push-pull amplifier to generate a square wave? instead of using 4047 or 555.

10. ### wayneh Expert

Sep 9, 2010
12,388
3,244
You still need an oscillator to make the square wave, such as a 555. The amplifier increases the current to the level you need and changes pulsing DC into real AC.