We take wireless charging with many gadgets we use today, such as smartphones, among others. The past four decades, electronics such as calculators are relatively new discoveries, and most people are just surprised to have it and never even consider the ability to charge the device wirelessly. When new, old electronics usually rely on old school batteries to power.
One of the old school electronics was the HP-25 calculator, originally introduced in 1975. It is a breakthrough as the first programmed engineering calculator with a balance of features, size, and ease of good use. HP-25 is an important device designed by engineers for engineers, and while it’s old, still using today.
One electronic hacker has a 25 father’s cellphone bought around the time he was born, and one of his weaknesses was a limited battery package design. The battery uses a pair of NiCD cells that stop working years ago. To make a calculator more useful at this time, the owner set out to design a battery that can be refilled to replace the original using a modern lithium polymer battery and wireless charging capabilities along with USB charging.
The result is an old school calculator of more than four old decades that can be placed on the QI power pad for charging. The battery pack can also be deleted and connected using a micro-USB cable to charge when wireless is not an option. The modern battery package also packs in 900mAh juice, provides a lot of power.
The new battery package is designed to replace the original without modification on the required calculator. It is also equipped with a low battery indicator. The battery pack is designed using Fusion 360 and is based on original battery measurements. It is a challenge because the original battery pack is designed for injection molds and has complicated geometry. Many hardware used in design comes from Texas instruments, and complete details can be seen here.