9v 1.5A on a Twin Fami: Yes or no?

Started by boye, October 26, 2020, 08:59:36 am

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boye

I'm planning to use a 9-volt 1.5 amp power supply on my twin fami. I've heard that it uses a 7805 regulator. So, is this a good idea?
Can't find the FDSLoadr PC program? Get it here. It took me way too long to find.

boye

Can't find the FDSLoadr PC program? Get it here. It took me way too long to find.

MWK

It's the other way around. You need to stick to the Voltage (more/less). Amps is the more the better.
For my Twin Famicom I'm successfully using switching power supply rating at 9V/2A (center positive!) and it never even broke a sweat (we're talking like 48~~72hrs straight ON during fCON parties :o ).

P

Yes, as MWK said, voltage (unit: volt) has to match the specs (within the tolerance). Current (unit: ampere) is what is taken as much as needed as long as enough is supplied for the whole system. The required current is higher if you use more peripherals and power hungry flashcartridges.

Many video games of the era used a 7805 voltage regulator, but each system may still have a bit different tolerance due to other factors I'm told. Don't only look at the 7805 tolerance, which is something crazy like 7-25 V. The voltage you feed to any Famicom or NES should probably be within 9-11 V like it says in the power FAQ.


Also don't forget polarity. The Twin uses a center-positive plug while the Famicom uses a center-negative plug. Using wrong polarity will likely fry something.



Sho

Use this if you really want an AC adapter that provides pretty clean energy and compatible with the Twin Fami:

https://www.digikey.com/en/products/detail/triad-magnetics/WSU090-1300-13/6600195

This is 7.6V, 1.25 amps & center positive which is dead on to what the OEM plug would provide.  I use Triad plugs for almost all of my systems, and I stand buy them 100%.

P

Ah right, the Twin uses a 7.6 V AC-adapter, not 10 V like the Famicom, so 7.6 V is obviously fine for it. But you shouldn't go under 7 V or you would be out of spec even for the 7805 itself.

Sho

Yeah, yeah.  I often wonder how they came about using something much lower voltage, considering the plug used for a typical Famicom Disk System uses a 9V adapter by comparison.  Perhaps a much more efficient PCB?

P

I don't know how it works either. Although the 7805 can support up to 25 V, a higher voltage means it generates more heat which the system isn't designed for (there is usually a heatsink on the 7805 which can only take so much). But I don't know if a few volt lower than 10 V is bad for any reason on a regular Famicom. Lower than 7 V is definitely bad, because the 7805 needs at least a 7 V input to guarantee a 5 V output.

Safest is to stay close to the system's official AC-adapter's specs in terms of voltage. In terms of current however, more is better. Especially if you use flashcartridges.