Conference rusure::nintendo

    Don,
    
    	I don't know for sure, but I'd be QUITE sure if you called Radio
    Shack that they'd be able to tell you.  
    
    Patty

<    I'd like to try to hookup my kid's Nintendo set to a DC power supply
<    (to use it in an RV while driving).  The regular AC adapter says that
<    it puts out 9V AC at something like 800mA.  Does anyone know if
<    plugging it into 9V DC will hurt the system?  ...
<    ...Buying a Game Boy is NOT an option.  Any opinions on using DC power? 
<    Also, does it really sink 800mA?
    
Don,

			AC does NOT!!! = DC. 

You might get away without 'smoking' the NES, but it probably won't function
either.  Somewhere inside the NES system power circuitry the 9v AC is converted
to DC (not necessarily 9vdc) to drive logic circuits, but if you put Direct
Current (DC) into the same "plug" the power circuts which are supposed to do
the conversion aren't going to work (i.e. no voltage/current to the logic
circuits). 

I'm not familiar with NES particulars, but basic theory indicates that at best
you'd be wasting your time, and at worst you'd damage your NES unit. 

Have you considered a power "inverter" to convert the 12 DC to a low power
110v AC signal.  The 100 to 200 watt models run around $80-$90 and could be
used for other things as well.	Kind of expensive if the NES is all you want
it for, but....

Al

>Somewhere inside the NES system power circuitry the 9v AC is converted
>to DC (not necessarily 9vdc) to drive logic circuits, but if you put Direct
>Current (DC) into the same "plug" the power circuts which are supposed to do
>the conversion aren't going to work (i.e. no voltage/current to the logic
>circuits). 
    
    I'd assume they just use diodes to rectify the AC, so feeding in DC
    should be OK as far as that goes.  What I'm not sure of is...
    
    	- whether it needs an AC signal for some other obscure reason
    	  (to sync timing circuits?)
    
    	- how much current the box draws.  The adapter I have is only rated
    	  for 1/2 amp.
    
    Anyone have any schematics?

Listen to Patty in Note .1!  My brother-in-law has a customized
van with a slot for a Nintendo game included.  The manual says
see Radio Shack for a converter that plugs into the cigarette
lighter.

Ray T.

    I agree with Ray in .4   -   I looked at conversion vans that had TV
    and space for VCR and NES.  You might try calling a local van
    conversion outfit.  I'll bet they've done it.
    
    Steve

re: .-1    
>    What the power supply that plugs into the wall does is change the 110v
>    AC to 9v 800mA DC, so all that the head unit sees is the 9v 800mA DC,
>    so having the 9v 800mA DC coming from anyway would be sufficient, as


According to the markings on the power supply on my NES, the output of 
the adapter is 9v AC (not DC) at 1.3A. I haven't metered it, but I'd 
be real supprized if it supplied DC... 


Arlan

    Well, I just looked at mine Nintendo setup, and you are correct.  I 
    was just basing my opinion on what the other notes had said, assuming 
    that the Nintendo ran off of DC.  So I will erase my previous note
    as it is incorrect.

    J

The conversion is easy. I've done it for Atari and Coleco as well. All
you need is a power connector and resistor(s) from Radio Shack. Total
cost is about $5.

First of the Nintendo power requirements.... The xformer says 9VAC @
1.3A. The bottom of the unit says 850ma. I measured 325ma DC and 50ma
110VAC (using a bridge rectifier). BTW, that makes the xformer about 
75-80% efficient. The extra capacity is no doubt for optional(?)
equipment or test equipment that connects to the bottom connector!?

Anyway, the 9VAC is converted to DC by a bridge rectifier then filtered
by an electrolytic. The DC goes directly to the front panel power switch.
The switched DC from the power switch goes back to the power board to
a 5VDC regulator (7805) and to the RF out circuitry. The 9VAC is not
used anywhere else or for any timing purposes.

Remember that the 9VAC is RMS. The DC voltage is loaded down peak-to-peak.
I measured 11 VDC. Connecting DC directly into the AC jack should work
as long as you input the correct voltage. The 7805 regulator should take
9VDC and convert it to 5 VDC but I'm not sure if the RF modulator
will work at 9V! You could try it. You won't smoke anything. Jusy don't
connect the auto cigarette power directly into the AC plug, that might
smoke the RF circuitry ( it won't hurt the rest of the unit). Note that
the audio/video out circuitry  uses the 5VDC power from the 7805.

Finally here's what I did on all my units. Measure the voltage (V2) and 
current at the front power switch, measure the voltage (V1) at your
auto cig lighter with the engine running (alternators crank out voltages
higher than the battery in order to charge) then get a resistor R=(V1-V2)/I 
(Ohm's law) and power connector at RS. Remember to get the correct power
rating P = V1I. The resistor will probably be in the 10 Ohm, 1 Watt range.
Drill a hole in the bottom unit for the power connector. Make a cable to 
plug into the auto cigarette lighter. Use the resistor(s) as a "shunt 
regulator" between the auto power and the Nintendo power switch and you're 
done! Total cost about $5-6 and a couple hours of work. Of course, now
you need a portable TV that also runs off the cigarette lighter power.
That could run you $200 for color! And then you have to find a way to
fasten it all down while under way so it isn't a safety hazzard!

Reply .9 pretty much says it all, but I'd just like to add a little too.

I built a converter box to run the NES and a portable TV off of the car's
cigar lighter a few years back.  I put an RFI filter, transient absorbers,
and a voltage regulator in the box along with fuses.  It was an awesome
overkill of a design!

I basically designed the unit by measuring the voltage at the 7805 with the
NES under normal operating conditions (line voltage, kids playing, etc).  I
then configured a voltage regulator IC to deliver exactly the same voltage
at the 7805.  I added some zeners and rectifiers before the voltage
regulator IC to prevent damage from the alternator's spikes and "current
dumping" habits.  The RFI filter was for alternator and distributor noise.
I also added fuses to the outputs so that the converter would survive the
kids' "use" of it.

In retrospect, after playing with the NES on a bench supply, I'd say the
regulator was not needed, a simple zener diode setup would do most of what
the stuff I put in did.

If you do use a Radio Shaft unit see if anyone has dissected one and knows
what RS uses for RFI and spike suppression.  My guess is they use something
out of a car radio, if so that should be good enough.  Then a zener or
special automotive regulator would be all that you'd need.

My final piece of advice and addendum is to bite the bullet and BUY the
GameBoy.  Having the NES and a TV setup in the car while you travel, along
with the cables and cartages laying around, is not all that convenient!

Add to this the fact that you'll want to stash all of this stuff each time
you stop, to avoid being ripped off, makes a GameBoy a MUCH better "solution"
for the car environment since it consumes less space, is easier to stow, and
can be passed around to other players easily (as opposed to the player
getting into "playing position" while the car is moving).

Just another IMHO...
Stra...