Re: Controlling 12V from 5V

ehsjr wrote: 
Buddy Smith wrote:

John Fields <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:


---
MOSFET flavors don't include NPN and PNP. :-)



Also, don't forget the damper diode across the coil... 




err Power MOSFETs I mean :)

I have TIP120s.

I'm really glad i'm not posting this with my IEEE email address...I'd
get banned for life :)

--buddy 


The diagram below assumes that your door lock is
wired such that the +12V is switched. Also, it
is designed so that you don't have to break
the existing doorlock wiring - just tap into it at
one point.


               +-----DoorLock-------Gnd
               |
               +-------|<--------+--Gnd
               |    D1 1N4002    |
               |                 /
               |                 \ R2
               |                 / 10K
               |                 \
              e \       R1       |
          Q1     |----/\/\/\-----+
       TIP120 c /      470       |
               |                 |
               |                 |
+12------------+                 |
                                 |
+5 from micro--------------------+

If your micro can source > 25 mA, change R1 to 220 ohms.

Ed 

Errrp!  I managed to screw that up, royally.
A large part (inverter & converter) is missing from
the first diagram, and the second diagram isn't there
at all. Hopefully, I'll get it right this time:


The diagram below assumes that your door lock is
wired such that the +12V is switched. Also, it
is designed so that you don't have to break
the existing doorlock wiring - just tap into it at
one point.


               +-----DoorLock-------Gnd
               |
               +-------|<--------+--Gnd
               |    D1 1N4002    |
               |                 /
               |                 \ R2
               |                 / 10K
               |                 \
              e \       R1       |
          Q1     |-----/\/\/-----+
       TIP120 c /       470      |
               |                 |
               |    Q2 2N3906    |
+12------------+-----e     c-----+
               |      \___/
               |   R3   |    R4    Q3 2N3904
               +--/\/\/-+---/\/\/--c     e------+-Gnd
                  10K        470    \___/       |
                         R5           |   R6    |
+5 from micro----------/\/\/----------+--/\/\/--+
                        3.3K              33K



The diagram below assumes that your door lock is
wired such that the Gnd is switched.


               +-----DoorLock-------+12
               |
               +------->|--------+--+12
               |    D1 1N4002    |
               |                 /
               |                 \ R2
               |                 / 10K
               |                 \
              c \       R1       |
          Q1     |----/\/\/\-----+
       TIP120 e /      470       |
               |                 |
               |                 |
Gnd------------+                 |
                                 |
+5 from micro--------------------+

If your micro can source > 25 mA, change R1 to 220 ohms.

Ed


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