'Unique' system hardware config

[Michelle Lawson]

When I moved recently into the house I live in, there was as 12VDC UPS that was left. Looks like it was used to keep their internet providers equip up if power went out. I say 12VDC, because that is what it puts out, not 120VAC.

So, I could run that 12VDC through a DC-DC power supply to give me the 5VDC that the RC2014 requires. But first I need to know what a typical current draw is for a standard out of the box RC2014 Pro is. So, if anyone has any info along those lines..... Thanks

[Olev Toom]

Hello!

I can't measure the power consumption of my system because it's been up for 192 days and I'd like to see how much longer it will last. 

However, it's powered by a 5 V/1,5 A wall wart, so this is the upper limit of the current consumption (for an 8-card system).. 

Virus-free.www.avg.com

On Sat, Nov 15, 2025 at 4:37 AM Michelle Lawson <michelle...@gmail.com> wrote:

When I moved recently into the house I live in, there was as 12VDC UPS that was left. Looks like it was used to keep their internet providers equip up if power went out. I say 12VDC, because that is what it puts out, not 120VAC.

So, I could run that 12VDC through a DC-DC power supply to give me the 5VDC that the RC2014 requires. But first I need to know what a typical current draw is for a standard out of the box RC2014 Pro is. So, if anyone has any info along those lines..... Thanks

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[Alan Cox]

So, I could run that 12VDC through a DC-DC power supply to give me the 5VDC that the RC2014 requires. But first I need to know what a typical current draw is for a standard out of the box RC2014 Pro is. So, if anyone has any info along those lines..... Thanks

It varies enormously. The basic setup uses very little power but if you add some of the more "heritage" NMOS based components then it rises somewhat as the TMS9918A and similar parts are a lot more power hungry. Adding a PS/2 keyboard card will also bump it up as it powers they keyboard although most are very power friendly.

The big killer though is floppy disks, especially older ones.

For most cases you are going to be more than fine if it can provide 10W or so, which means any typical converter ought to do the trick. If you want to be retro there are switched mode boards that fit in the same footprint and pinout as a 7805.

Alan

[Phil G]

I just measured my Z-Pro and it varies around 150mA peaking 200mA as it accesses CF etc
Mine is powered by usb via the FTDI serial adapter, consumption is well within usb2 spec so its never had an additional power supply.

A switching DC-DC would give you a longer battery life during a power outage but make sure its well filtered, they can be noisy (electrically, not audibly)  :-)

Cheers

Phil

[Michelle Lawson]

Well, I turned the UPS(?) over and grabbed some data off it. It's a CyberPower CSN27U12V-NA2 (https://www.cyberpowersystems.com/product/telecom/indoor/csn27u12v/). The specs say 27W but the sticker on the back says 24W, so.... Given the low power of the RC2014 and if I stay with the same CMOS family of parts, even a simple 5V/3A regulator (LM323K) should work, or maybe an adjustable LM338K variant. Part of my planned use for the RC2014 is to monitor the AC power, and if it goes out, message my servers (via serial) to shutdown. Hey, it's all a hobby; sure won't be running any AI LLM on this or any other Z-80..... Although, there was Eliza.....

[Phillip Stevens]

On Saturday, 15 November 2025 at 10:37:28 UTC+8 Michelle Lawson wrote:

When I moved recently into the house I live in, there was as 12VDC UPS that was left. Looks like it was used to keep their internet providers equip up if power went out. I say 12VDC, because that is what it puts out, not 120VAC.

So, I could run that 12VDC through a DC-DC power supply to give me the 5VDC that the RC2014 requires. But first I need to know what a typical current draw is for a standard out of the box RC2014 Pro is. So, if anyone has any info along those lines..... Thanks

The standard RC2014 Pro backplane has a space for a 7805 device. But the best thing to do is get dc to dc conversion equivalents from eBay vendors, which are usually cheaper then the “real thing”. They typically can be driven off anything up to about 40v.  They supply a clean 1A 5V with close tolerance and on board capacitors.

I have a 15V supply on my bench and it supports all my different machines and the RC2014 via the 7805 clone devices. 

[Phil G]

ML: >> even a simple 5V/3A regulator (LM323K) should work, or maybe an adjustable LM338K variant.
it will, but will waste power as heat. A dc-dc switcher runs cool and takes less current from your UPS battery which if its a small unit, might be beneficial.

[Michelle Lawson]

I'm probably going to start with the LM323K since I have them already. If that works, then switch to a DC-DC converter. My thinking anyway.