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

• posted

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

• posted

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 positive wire side lead.

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

• posted

In response to what Christopher posted in news: snipped-for-privacy@4ax.com:

Not if it goes into a transformer.

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

--
Joe Soap.
JUNK is stuff that you keep for 20 years,
• posted

--
9VAC is about 12.7VRMS and, after two diode drops going through a
full-wave bridge, will be about 11.3V across the reservoir cap/input
• posted

Thanks to all of you.

René

• posted

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.

"Rene Ruppert"  wrote in message
• posted

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.

--
John G

• posted

you should probably find out. it may run off 12V DC just fine.

probably. the most efficient and possibly cheapest way would be to modify the device.

Bye. Jasen

• posted

Good Call Jerry,

Rene,

Something Like this from Maplin Electronics.

Have fun,

• * * Christopher

Temecula CA.USA

• posted

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

Christ> Hello Rene,

• posted

you may be thinking of a sidactor, diac, or MOV or some other ...

zeners exhibit a near constant voltage drop when reverse biased.

Bye. Jasen

• posted

--
You've got _two_ things wrong, actually.

The first is that you're top-posting, and the second is in thinking

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