Virtual Boy power supply compatibility

AC output will not work without blowing up the poor Virtual Boy; It requires DC.

A Sega Mega Drive adapter would work. 🙂

Fascinating! It’s interesting what new things can be learned that previously went undefined. 20 years later and we are still discovering new information from Virtual Boy.

TheForce81 wrote:
After opening up both taps, the electronics are the same for both, so it seems it doesn’t matter if you feed the VB AC or DC.

I don’t own either tap, so I can’t check. What do “the electronics” consist of? Is it a bridge-rectifier, one to four individual diode(s), or something else? AFAIK, diodes are the only way to convert AC or DC to DC with a given polarity. Could anyone post some photos?

After measuring the voltage, the DC adapter with the USA tap outputs 8.75 volts on the pins of the tap and the Japanese tap with the AC adapter outputs 4.85 volts. So I am not completely sure what is happening with this on the voltage regulator. It seems that there is some automatic switching going on to account for these differences.

I doubt that the internal regulator in the VB could operate on 4.85V DC. Besides, it says right on the VB that it requires at least 6V. Are you sure you’re not measuring AC with the DC setting on the meter? This will give a false reading. On the other hand, I don’t think the VB would be able to handle AC on the battery terminals, even at the right voltage – hence the rectifier(?) in the tap.

TheForce81 wrote:
You do not own an adapter tap 😉 ? How do you power your VB then?

I use a Performance adapter, mainly. I also have a custom “adapter tap” that a friend made for me.

Thanks for the pics, but without seeing the actual circuitry on the other side, I still have to speculate on what the components actually do. It does have a diode, so I’m not sure if it’s putting out AC or pulsing DC. Either one would still mess with the DC setting on a meter. I still don’t think the VB can directly handle AC, but half-wave rectified (pulsing) DC might work. It’s not very efficient, though.

The black thing on the left wrapped in copper wire is probably a 1:1 transformer used to filter out common-mode noise (which is something Nintendo also used inside the SNES). I think the green thing on the right that looks like a resistor is actually another inductor for additional noise filtering. The black, cylindrical thing with a white stripe is the aforementioned diode. It is probably there to protect against hooking up an adapter with the wrong polarity, and the partial rectification of AC is just a (possibly intentional) side-effect.

• This reply was modified 9 years, 2 months ago by RunnerPack.

That was the last piece of the puzzle, TheForce81! 🙂

Using that information, I made a schematic. Note: upon further consideration, I’ve decided that the green thing is, in fact, a resistor. Specifically, I believe it is a 1 ohm, “flameless” (i.e. it won’t produce a flame when it burns out due to over-current) resistor, and it is being used here as a fuse.

TheForce81 wrote:
Thanks for that nice schematic, though since my electronic schematics knowledge isn’t that up to snuff, what does this mean to you considering inputting 10DC or 10AC?

Exactly as I explained before: the diode is there for reverse-polarity protection and also serves as a half-wave rectifier.

If you connect an adapter providing DC (with the negative on the center contact of the plug), it will forward bias the diode and you’ll get about 0.7v less than the input voltage (due to the diode’s voltage drop).

If the center of the plug is positive, the diode will prevent any current flow, and the VB won’t run.

If you input AC, the diode will only let half the wave through, so you’ll end up with pulsating DC at about 0.32 times the input voltage (or 0.45 times the RMS voltage) at the VB.

Since the VB needs a minimum of 6V, your adapter should, ideally, be providing at least 13.33Vrms. If you do the math with 10VAC, you only get what you measured with the meter set to DC: about 4.8V. I can’t account for why the VB still operates, other than to say that these are unregulated adapters we’re talking about, so the actual voltage can swing quite a bit, depending on the load they’re driving.

The main take-away from all this is that the VB is not picky at all concerning what adapter you power it from. The range of voltages seems to be even larger than what is printed on the VB (although I wouldn’t go too high). The only thing that definitely won’t work is using one with a center-positive (positive-tip) plug (unless you rewire the tap ;-)).

You just can use one of those stabilzed DC power supplies, I use one for mine and set it to 9 Volts DC. It might be that the VB works also with 6 Volts, but as far as I remember there are 6 x 1,5V AA batteries in the battery pack (didn´t check now) which adds up to 9 Volts then.
Then you don´t have to deal with rectifiers and capacitors and stuff like that.
In Europe the power supply needs to be able to handle around 230 Volts AC Input, I think in Japan there is still 100 Volts AC.