Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

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system11
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Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by system11 »

I've got a New Net City, there's no -5v of course but I have some very old games which require a strong 5v to work.

Are there any Negatrons that are to to the task? I need at least 1A -5v.
Is there any conceptual problem with simply fitting a second power supply since both would share common ground?
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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by nem »

system11 wrote:Is there any conceptual problem with simply fitting a second power supply since both would share common ground?
I would just do this.
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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by system11 »

I think it's looking like the tempting option. What's the best quality JAMMA PSU you can get these days? At least the NNC has a cavernous amount of space in there to mount the second PSU.
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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by nem »

Why double up on everything? You already have +5V and +12V (and +3.3V) from the SUN. A single rail PSU will do fine. As long as the outputs are floating, you can tie the positive output to GND and you have negative voltage.
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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by system11 »

How would you know if one was "floating" or not? Mostly common ground seems to be connected to earth on ones I've checked. Would this do the trick?

https://www.ebay.co.uk/itm/DC-5V-Univer ... 2586857557
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Re: Adding -5v to a Naomi/NNC/JVS - 2nd psu? negatron?

Post by nem »

Looks fine yes.

As per Wikipedia, "most electrical circuits have a ground which is electrically connected to the Earth, hence the name "ground". The ground is said to be floating when this connection does not exist". So neither the positive output nor the negative output is connected to earth ground. When the outputs are separately labeled positive and negative they're floating (well, should be. Easy enough to check).
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