Controlling 12V from 5V
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
|||||||||||||||||||||||||||||||||||||
|
Posted by ehsjr on June 30, 2005, 7:14 am
Please log in for more thread options Buddy Smith 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 | |||||||||||||||||||||||||||||||||||||
|
Posted by Ban on June 30, 2005, 11:24 am
Please log in for more thread options ehsjr wrote: > Buddy Smith 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 But the TIP120 is an NPN transistor, which will need almost +14V on the base to switch on +12V. Maybe you can use a TIP125, but with the emitter at +12V_in, or you switch with the TIP120 in the gnd-leg of that solenoid, which would be easier. -- ciao Ban Bordighera, Italy | |||||||||||||||||||||||||||||||||||||
|
Posted by ehsjr on June 30, 2005, 5:36 pm
Please log in for more thread options
Ban wrote: > ehsjr wrote:
> >>Buddy Smith 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 >
> > But the TIP120 is an NPN transistor, which will need almost +14V on the base > to switch on +12V. Maybe you can use a TIP125, but with the emitter at > +12V_in, or you switch with the TIP120 in the gnd-leg of that solenoid, > which would be easier. Hi Ban, The TIP120 will turn on *way* lower than that. The emitter is not at +12 - there's about 60 ohms between it and ground, through the door lock. So you need only about two diode drops to get it to start conducting. But see the correction I was posting even as you were posting your question. I totally mangled the original diagram. I cut-and-pasted myself into oblivion when I drew it, and ended up leaving out most of it. I hate it when that happens! :,; Ed Ed | |||||||||||||||||||||||||||||||||||||
|
Posted by ehsjr on June 30, 2005, 11:29 am
Please log in for more thread options
ehsjr wrote: > Buddy Smith 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 | |||||||||||||||||||||||||||||||||||||
| Similar Threads | Posted |
| Controlling 12V from 5V | June 29, 2005, 3:35 pm |
| controlling | April 10, 2007, 6:25 am |
| controlling many switches from the PC | December 2, 2004, 6:46 am |
| LCD controlling with comparators | January 15, 2005, 6:50 pm |
| op amp controlling a mosfet | July 18, 2006, 1:20 pm |
| Controlling hundreds of LEDs | December 21, 2004, 8:41 pm |
| Controlling a motor with a transistor and a PIC | June 7, 2006, 11:14 pm |
| Re: Controlling a relay via cellular phone..... | July 12, 2006, 6:23 pm |
| Re: Controlling a relay via cellular phone..... | July 12, 2006, 7:03 pm |
| Re: Controlling a relay via cellular phone..... | July 12, 2006, 8:50 pm |
| controlling 2 stepper motors along x and y axis | September 11, 2006, 1:03 pm |
| controlling dc motor direction (help a newbie, please) | October 28, 2006, 2:09 am |
| Re: Controlling a relay via cellular phone..... | July 17, 2006, 8:36 am |
| Re: Controlling a relay via cellular phone..... | July 2, 2008, 10:27 pm |
| Controlling a motor in presence of phase shift | July 3, 2006, 12:09 am |
>