$10 UPS Power Supply

[Steve Curd]

First off, I am LOVING my Altair-Duino. I built an 8800 in 1975 and had so much fun then, it is a kick to finger-bone in machine language 8080 code again!

However now, as before, the RAM is completely volatile. Nothing worse that spending 30 minutes switching in a program and losing power; or have a running program and needing to unplug and move your machine.

Unlike the 1974 version, the good news is keeping our Altair-Duino battery powered for a couple of hours is feasible!  I've built a simple UPS I'm super happy with, so I'm sharing it with you here.

I measured the current draw of my Altair-Duino from the 9V dc supply at about 200ma running the kill-the-bit program. So a 9v battery supply on a constant charge should be able to power a running Altair-Duino continuously, and when power fails or is disconnected, a 9v Li-ion battery will continue to supply sufficient current. All you need is the battery, and a power cable!

I recommend this battery:

https://www.amazon.com/dp/B0B9G9RQG3?th=1

"HW 9V Li-ion Rechargeable Battery, 9 Volt/1000mAh(9000 mWh) Long Lasting Rechargeable Batteries with Micro-USB, 1000 Cycles Charge, 1.5 Hrs Fast Charging, LED Indicator"

Be careful with other brands; I initially tried another brand, however the internal charger did not supply sufficient current to run the Atari-Duino. Even when connected to a USB charger, the 9v battery would run down while the machine was on. The HW brand above appears to have a 500ma internal charger, so it can provide sufficient current to power the Atari-Duino while also charging the battery.  

I then made a power cord by soldering a 9v battery clip to a 5.5mm x 2.1mm barrel power connector which fits the jack on the back panel of the Altair-Duino. I had one of these laying around from an earlier project:

https://www.amazon.com/gp/product/B07C7VSRBG/?th=1

"DC Power Cable 12V 5A Plugs Male Female Connectors for CCTV Security Camera Pigtail Power Adapter Connectors (5.5mm x 2.1mm, 10 Pairs)"

Along with any 9v battery clip, like these:

https://www.amazon.com/gp/product/B0D5Q9CYKZ/

"12 Pack T-Type 9V Battery Clip, 1 Dozen 9V Battery Connector with Hard Plastic Case, 9 Volt Battery Connector with Wire Leads for Experiment"

And that's it! Solder together the red wire of the pigtail to the red wire of the battery clip, and the black-to-black wires. Plug the pigtail into the power connector of your Altair-Duino, and connect the charging cable into the bottom of the 9v battery and to a USB charging block. You are now running your Altair-Duino from a fail-safe UPS.  I found with the HW battery, I get about 2 hours of power.running kill-the-bit program... not too bad.

I have attached a couple of photos showing the Altair-Duino UPS in operation.

Enjoy!