# How to convert 12V DC into 9V AC in car?

Discussion in 'Misc Electronics' started by Rene Ruppert, Mar 19, 2006.

1. ### Rene RuppertGuest

Hi,

I would like to install my old video game console SNES in my Camper.
The console expects 9V AC (though I don't know why it isn't using DC!?).
Is there a cheaper and more efficient way than converting from 12V DC to
230V AC and back to 9V AC by using the original power supply?

Thanks.

René

2. ### ChristopherGuest

Hello Rene,

A 9 volt ac receptacle will accept 9 volts dc connected in either
direction. Remember AC is DC sort of for each half of the cycle.

You need to convert the 12 volts dc down to 9 volts dc by placing an
inline 3.1 volt zener diode (1 amp should work) in series or spliced
into the connecting power cord you use. If you didn't use this voltage
dropping diode the game console voltage regulator would run extra hot.

These zener diodes mount backward compared to regular diodes. In other
words the diode line/arrow must point away from the game console
towards the positive of where the voltage is coming from, on the

Cost is less than one dollar or euro

Or

You could place five 1 amp power diodes in series to shave off the
extra three volts. 5 x .6 volts = 3 volts

Good Luck,

* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com

3. ### Joe SoapGuest

Not if it goes into a transformer.

And if it doesn't, it is probably rectified directly to give about 13V DC.

4. ### Rene RuppertGuest

Thanks to all of you.

René

5. ### Jerry G.Guest

The best way is to build a circuit using a 12 Volt regulator. If you use
a zener in series, you will be very restricted, unless you can find a
zener of a high enough wattage rating to be practical. For all
practicality, you would want something rated to at least one Amp or
more. This will be hard to achieve with a simple zener diode.

You would find it more practical to find a universal power adaptor for
the car. Radio Shack, The Source, and other places like that sell them.
They are not expensive, and they work very well. These are dependable,
and meet CSA and UL standards for safety and dependability.

--

Jerry G.

Hi,

I would like to install my old video game console SNES in my Camper.
The console expects 9V AC (though I don't know why it isn't using DC!?).
Is there a cheaper and more efficient way than converting from 12V DC
to
230V AC and back to 9V AC by using the original power supply?

Thanks.

René

6. ### John GGuest

Without knowing what is inside you cannot be sure DC will work into an
AC device..
I have an audio mixer which requires AC and will not work on DC.

7. ### ChristopherGuest

Good Call Jerry,

Rene,

Something Like this from Maplin Electronics.

http://www.maplin.co.uk/Module.aspx?TabID=1&DOY=20m3&ModuleNo=37423&criteria=

Have fun,

* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com

8. ### quietguyGuest

Just butting in to ask if this option actaully works - it is a long time
since I've read about zeners, but I thought they just started to conduct when
the applied voltage reached or exceeded their nominal rating - ie when 3.1 or
more volts is applied to a 3.1v zener it conducts, with only a small voltage
drop across it. I didn't think that it dropped its voltage rating when
conducting, as it would in the scenerio below.

Have I got it wrong?

David