Battery Questions

[philba]

You might want to take a look at the LCDs contrast adjustment. I suspect it's proportional to Vcc but you never know.

 

[nasibrahim]

Hi PICers,

I want to design a 24V DC to 50Hz/240AC power inverter. My choice of PIC is the 18F452 (HWPWM). But I am not sure whether the ADC conversion time would be short enough for dynamic correction.

Any thoughts

nasib rahim

 

[Hero999]

What's that got to do with the subject being discussed?

Please post on topic.

 

[Urahara]

Am bringing this thread back up again. Another basic question(?) from a newbie

My plan is to come up with a project that can run off batteries and one of those wall-wart. The latter will "take over" the batteries when it is turned on.

Based on advice and recommendations discussed here, pretty much settled on 3xAA/AAAs, ie abt 4.5V.

I just tested with one of those wall-warts i had at home that has adjustable voltage from 3V to 12V. When I set it to 3V, I measured abt 4.7V, at 4.5V setting, it was abt 6V !!

Based on earlier discussions, this is obviously too high. If these wall warts are a necessary evil, what effective design can one have to tackle these challenges?

Your inputs, thots, recommendations are welcomed, as always. Thks!

 

[futz]

I just tested with one of those wall-warts i had at home that has adjustable voltage from 3V to 12V. When I set it to 3V, I measured abt 4.7V, at 4.5V setting, it was abt 6V !!

Based on earlier discussions, this is obviously too high. If these wall warts are a necessary evil, what effective design can one have to tackle these challenges?

Wall warts will always read way high with no load. Their output varies with load. I would say a regulator is a must-have when powering from wall wart.

 

[Willbe]

The latter will "take over" the batteries when it is turned on.

Steering diodes will ensure take over when the wall thing is 0.7 V to 1 V above the batt V.