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Topic: 12v 5v power supply, and transistor question (Read 2 times) previous topic - next topic

tigerbomb8


Yes that look fine on the FET.

ok that is good to know. you and CrossRoads have been a great help
now i just need to find a easy to use library for the DS1307 RTC

Grumpy_Mike


tigerbomb8


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do i really need caps on the regulator.

Yes I don't say these things for fun.

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the 5v one i use to power my servo is doing fine with out them

No it is not, it is just that you haven't noticed the instability it causes, it is not doing fine.
ok i will add them in the final plan
and i fixed the mosfet

Grumpy_Mike

Quote
do i really need caps on the regulator.

Yes I don't say these things for fun.

Quote
the 5v one i use to power my servo is doing fine with out them

No it is not, it is just that you haven't noticed the instability it causes, it is not doing fine.

tigerbomb8

#8
Nov 28, 2011, 01:49 pm Last Edit: Nov 28, 2011, 03:08 pm by tigerbomb8 Reason: 1

You need capacitors on those regulators, see the data sheet for exact minimum values but I would put a 0.1uF across the input and output of both regulators plus put an additional 47uF capacitor on the input of the first regulator.

The FET needs to have the load connected to the 12V, so source to ground, drain to load, other end of load to +12V.

do i really need caps on the regulator. the 5v one i use to power my servo is doing fine with out them

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