3V circuits.......

[Janitor Tzap]

I have a pager unit for a home alert pad setup.

Basically to alert me when my aged mother is up, and running around at night.

But after using the pager for a week.
The batteries would be nearly dead, even when I put it in the off position.

Turns out the off button isn't really off, it just cuts the power to the receiver, buzzer, display, and flasher circuits.
Only power is still sent to the PIC controller.

Now I just pull the batteries when I get up in the morning, and put them back in when I try to go too sleep.

Only I must reset the volume, and preset the alarm sound every time.

I found that when the Voltage gets below 3V on the 2 X 1.5V AA cells.
The preset functions do not work very well.

I load tested the AA batteries, and they pass the test just fine.

Okay, now for the question.

Do PIC's need 3V or higher voltage for it to operate reliably?


Signed: Janitor Tzap

[dyarker]

Now I just pull the batteries when I get up in the morning, and put them back in when I try to go too sleep.

Don't know what particular voltage that PIC needs, but for sure it needs more than zero to maintain RAM.

From your description of what happens when you remove the batteries, RAM is where the settings are being stored.

[cheapNdisgusting]

They are expensive but Lithium batteries should perform much longer.

[Externet]

Hi Tzap.
Check that PIC data sheet for voltages.
Nice gadget, typical poor chinese execution with ram instead of flash, and flaky buttons.

I have replaced 2 AAs with 2 Lithium ion AAs in parallel on a camera, for much longer duration. If you have room, try a discarded cell phone prismatic battery shoehorned in (or 'canteen' attached outside !) And try to solder battery terminals instead of relying on springy contacts.

I have a couple of portable radios ( weather, shortwave) that had 3 banks of (4.5V) separate rechargeables inside for replaceable, crank, solar and they are now 3 sets of single Li-ion. Bye-bye problems.
Li-ion are 'free' salvaged from discarded cell phones.

[dacflyer]

if you can.. try to modify a rechargeable cell phone battery..3.7V and just use a modified 12v cell phone charger..then it can charge during the day and work at night..

just an idea...

[Janitor Tzap]

Thanks for your advice everyone.

I really don't want too tear a part the pager, if I don't need too.
I'll look into some rechargeable Lithium Ion AA Batteries, and charger.


Signed: Janitor Tzap

[haklesup]

a couple of 2200mAh NiMh should work well and cost less than Lithium which often are not rechargeable in the AA cell size.