mosfet as switch
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
Posted by lerameur on August 16, 2008, 6:26 pm
Please log in for more thread options hi, I have two 12v batteries which I am hooking up in parallel using a mechanical switch (via the ground). I am attempting to swap the mechanical switch for a mosfet so I can control them from a distance. I tried to model in pspice but this is harder then I imagine. I tried it experimentally, but when I hook up a iRFz44 , the batteries stays in parallel no matter the voltage in the base. anyone has an idea to overcome this. B | ||||
|
Posted by Jamie on August 16, 2008, 7:34 pm
Please log in for more thread options lerameur wrote: connections.. My guess is that you're using it incorrectly!. This Mosfet has a body diode in it, which means if you apply + voltage on the source, it'll be there at the drain. And the Gate is a voltage control device not a current device as you are using in terms of (BASE). You should at least have a pull down R to ground so that you keep the gate discharged!. IT's a very high Z input which can maintain a charge. You also can damage it. Since this component is a N channel device, you need to pull the (-) terminal of the battery to common via the Drain connection of the NMos and the Source goes to common.. The Gate will be switched on via what ever voltage needed. I didn't look at all of the spec's http://webpages.charter.net/jamie_5" | ||||
|
Posted by lerameur on August 16, 2008, 9:03 pm
Please log in for more thread options
On Aug 16, 7:34 pm, Jamie > lerameur wrote:
> > hi,
>
> > I have two 12v batteries which I am hooking up in parallel using a
> > mechanical switch (via the ground). > > I am attempting to swap the mechanical switch for a mosfet so I can > > control them from a distance. > > I tried to model in pspice but this is harder then I imagine. I tried > > it experimentally, but when I hook up a iRFz44 , the batteries stays > > in parallel no matter the voltage in the base. anyone has an idea to > > overcome this. >
> > B
>
> If you can't show the circuit then please try to describe its > connections.. > My guess is that you're using it incorrectly!. > > This Mosfet has a body diode in it, which means if you apply > + voltage on the source, it'll be there at the drain. And the > Gate is a voltage control device not a current device as you are using > in terms of (BASE). You should at least have a pull down R to ground so > that you keep the gate discharged!. IT's a very high Z input which can > maintain a charge. You also can damage it. > > Since this component is a N channel device, you need to pull the > (-) terminal of the battery to common via the Drain connection of > the NMos and the Source goes to common.. > > The Gate will be switched on via what ever voltage needed. > I didn't look at all of the spec's > > http://webpages.charter.net/jamie_5" the circuit is really simple. connection the ground of two batteries, the positives are not attached to anything. yes I could use an alligator clip and hook up the two grounds together. But I would like to use a semiconductor. I would need some sort of mosfet but when the gate is activated, it can let current flow in both direction, is there anything on the market that can do this? B | ||||
|
Posted by lerameur on August 16, 2008, 9:09 pm
Please log in for more thread options
> On Aug 16, 7:34 pm, Jamie
> > > > > lerameur wrote:
> > > hi,
>
> > > I have two 12v batteries which I am hooking up in parallel using a
> > > mechanical switch (via the ground). > > > I am attempting to swap the mechanical switch for a mosfet so I can > > > control them from a distance. > > > I tried to model in pspice but this is harder then I imagine. I tried > > > it experimentally, but when I hook up a iRFz44 , the batteries stays > > > in parallel no matter the voltage in the base. anyone has an idea to > > > overcome this. >
> > > B
>
> > If you can't show the circuit then please try to describe its
> > connections.. > > My guess is that you're using it incorrectly!. >
> > This Mosfet has a body diode in it, which means if you apply
> > + voltage on the source, it'll be there at the drain. And the > > Gate is a voltage control device not a current device as you are using > > in terms of (BASE). You should at least have a pull down R to ground so > > that you keep the gate discharged!. IT's a very high Z input which can > > maintain a charge. You also can damage it. >
> > Since this component is a N channel device, you need to pull the
> > (-) terminal of the battery to common via the Drain connection of > > the NMos and the Source goes to common.. >
> > The Gate will be switched on via what ever voltage needed.
> > I didn't look at all of the spec's >
> >http://webpages.charter.net/jamie_5"
>
> the circuit is really simple. > connection the ground of two batteries, the positives are not attached > to anything. > yes I could use an alligator clip and hook up the two grounds > together. But I would like to use a semiconductor. I would need some > sort of mosfet but when the gate is activated, it can let current flow > in both direction, is there anything on the market that can do this? > > B I think it is called a UJT, just need to find one in pspice... B | ||||
|
Posted by Jamie on August 16, 2008, 10:34 pm
Please log in for more thread options
lerameur wrote: > On Aug 16, 7:34 pm, Jamie
> >>lerameur wrote:
>> >>>hi,
>>
>>>I have two 12v batteries which I am hooking up in parallel using a
>>>mechanical switch (via the ground). >>>I am attempting to swap the mechanical switch for a mosfet so I can >>>control them from a distance. >>>I tried to model in pspice but this is harder then I imagine. I tried >>>it experimentally, but when I hook up a iRFz44 , the batteries stays >>>in parallel no matter the voltage in the base. anyone has an idea to >>>overcome this. >>
>>>B
>>
>> If you can't show the circuit then please try to describe its >>connections.. >> My guess is that you're using it incorrectly!. >> >> This Mosfet has a body diode in it, which means if you apply >> + voltage on the source, it'll be there at the drain. And the >>Gate is a voltage control device not a current device as you are using >>in terms of (BASE). You should at least have a pull down R to ground so >>that you keep the gate discharged!. IT's a very high Z input which can >>maintain a charge. You also can damage it. >> >> Since this component is a N channel device, you need to pull the >>(-) terminal of the battery to common via the Drain connection of >>the NMos and the Source goes to common.. >> >> The Gate will be switched on via what ever voltage needed. >> I didn't look at all of the spec's >> >>http://webpages.charter.net/jamie_5" >
Are you saying you want to put these batteries in series ?
> > the circuit is really simple. > connection the ground of two batteries, the positives are not attached > to anything. > yes I could use an alligator clip and hook up the two grounds > together. But I would like to use a semiconductor. I would need some > sort of mosfet but when the gate is activated, it can let current flow > in both direction, is there anything on the market that can do this? > > B I think at this point you maybe better off using a relay.. http://webpages.charter.net/jamie_5" | ||||
| Similar Threads | Posted |
| mosfet as switch | August 16, 2008, 6:26 pm |
| Power mosfet to switch 140 VDC | June 16, 2005, 6:11 pm |
| MOSFET switch problem | July 16, 2005, 11:14 am |
| Mosfet as a 12V Switch (and opto) | October 7, 2007, 12:46 pm |
| Mosfet switch issues | October 30, 2007, 4:18 pm |
| P-channel Mosfet switch? | April 16, 2008, 8:42 am |
| Switch 3A with a small reed switch | August 5, 2008, 10:20 pm |
| SiC Mosfet | August 1, 2005, 2:25 am |
| mosfet | July 3, 2006, 1:36 am |
| About P-MOSFET | September 21, 2006, 3:05 am |
| Mosfet | October 15, 2007, 5:44 pm |
| mosfet failure | August 12, 2004, 5:32 pm |
| How to bias a MOSFET amp? | August 27, 2004, 1:40 am |
| Dimmer through mosfet? | October 4, 2004, 5:31 am |
| q:mosfet circuit | July 29, 2005, 2:46 am |
>
> I have two 12v batteries which I am hooking up in parallel using a
> mechanical switch (via the ground).
> I am attempting to swap the mechanical switch for a mosfet so I can
> control them from a distance.
> I tried to model in pspice but this is harder then I imagine. I tried
> it experimentally, but when I hook up a iRFz44 , the batteries stays
> in parallel no matter the voltage in the base. anyone has an idea to
> overcome this.
>
> B