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5 volt supply from 4 c cells ?

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1Steveo

New Member
I need to power a Pic microcontroler from a 6 volt supply
Is it ok to use a 78L05 . Are can I use a 5.1 zenier diode? (How)

Thanks ahead
 

Sebi

Active Member
Maybe a zener also O.K.,but i recommend to use a low dropout regulator (LDO). 78L08 can work properly with min. 2V difference (in-out),the LDO need only 0.2V.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I've actually run PIC's a lot (while breadboarding designs) from a PJ996 6V battery (the big one with the springs on top), using just a series rectifier to drop 0.7V from the nominal 6V.

I've never had any problams doing that, although it's probably not recommended 8)
 

fabelizer

New Member
The problem with using a linear regulator (zener or 78 series) with a battery, is the regulator will waste power getting to your required voltage. Using batteries that match the rating of your parts is the best option. Be aware that battery chemistry determines that actual "new" battery terminal voltage, and it can be considerably higher than the nominal rated voltage. Be sure to keep "new" batteries within the "absolute maximum" range for your parts.

Also, if using re-chargeable batteries, the charging terminal voltage can (should) get higher than the nominal cell voltages. For example, a 3.7V Lithium may charge up to 4.2V. Or a 6V lead acid might charge at 7.2V. This has to be considered. But re-chargeables make using a linear regulator more tolerable as the batteries need to be recharged but not replaced as often. Again, be sure your regulator parts can withstand the charging voltage.

-fab
 
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