HP48GX RAM card design

[Jonathan Busby]

(01-21-2021 04:12 PM)Marco Polo Wrote:  

(01-21-2021 09:33 AM)wan Wrote:  There‘re two gold colored capacitors on the bottom right of the board, these two 440uf capacitors will provide power when changing batteries. They are larger than Paul's original design and provide longer holding time. I think they can hold for more than 20 seconds.

The reason for not placing the batteryholder on top is to avoid touching the batteryholder when pulling the card out. Pulling the card with batteryholder will apply shear force on it, which may cause the batteryholder to desolder over time.

Clever design, indeed.
Are you sure that 20 seconds are enough?
Just as an example, pulling-out the batteries from my Cynox cards requires some effort and doing it within 20 seconds is quite challenging

I've found that using plastic tweezers is the best solution, for me at least. Just make sure that the gripping ends of the tweezers have a texture that makes it easier to grab onto smooth surfaces.

Regards,

Jonathan