How to stop a standard calculator from automatically shutting down?

[JackJellyBean]

I was wandering if anyone had an idea of how to stop a standard calculator from automatically shutting down. I have hacked the calculator and im using it as a basic counter, but i cant keep it on for more than 10 mins.

Any idea's will be much appriciated.

 

[betwixt]

Re: Auto Shutoff Problem

It is probably a software function in it's IC. The best you can probably do is see if there is a key you can press that does not change the result on the display (for example M+ key if you are not using the memory) and periodicaly simulate the key being pressed with an external circuit.

Brian.

 

[JackJellyBean]

Re: Auto Shutoff Problem

Hi Brian

Thanks alot for the response. Tried it out and it works well (Great idea). Only problem is when you press a different button at the same time as that key, it gives an error. (but it very very few and far between!) Another possible solution iv come up with it using a solar powered calculator that does not switch off. Just need to find an old one and replace the solar cell with the equivalent battery.