Auto sensing power supply external/battery?

R

rikun

New Member
Hi,

I'd like to build a picaxe circuit that uses both batteries and external power. How could I make the circuit or picaxe auto-sense which one is present, and if both are present, disregard battery power and use external power?
 
B

BeanieBots

Moderator
Simply diode OR the power supplies.
The one with the higher voltage will be the one used.
Make the mains powered supply slightly higher so it is the one used when on.
The PICAXE won't know and won't care which is used.
If you want it to know, then fit a suitable potential divider on an analogue (or digital) input and feed it from the power supply side of the diode.
 
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