Controlling power mosfet

[3eprabu]

Guys need some help here . Im using a irf830 power mosfet to control a dc light , but for some reason i can't control the mosfet via the gate . The light turns on automatically without even supplying signal to the gate . I connected the source terminal to the negative of the battery , one side of the light is connected to the battery and the other is connected to the drain of the mosfet . I tried the same connection using a transistor and it worked fine . totally confused . need some help PLZ . I have tested the mosfet using a multimeter and its working fine .

 

[Gryd3]

Guys need some help here . Im using a irf830 power mosfet to control a dc light , but for some reason i can't control the mosfet via the gate . The light turns on automatically without even supplying signal to the gate . I connected the source terminal to the negative of the battery , one side of the light is connected to the battery and the other is connected to the drain of the mosfet . I tried the same connection using a transistor and it worked fine . totally confused . need some help PLZ . I have tested the mosfet using a multimeter and its working fine .

Please link the part# and a diagram to confirm which pins you are using.

 

[Martaine2005]

Here is the Datasheet.

EDIT: Look at the internal workings of the mosfet.

Martin

 

[Arouse1973]

Guys need some help here . Im using a irf830 power mosfet to control a dc light , but for some reason i can't control the mosfet via the gate . The light turns on automatically without even supplying signal to the gate . I connected the source terminal to the negative of the battery , one side of the light is connected to the battery and the other is connected to the drain of the mosfet . I tried the same connection using a transistor and it worked fine . totally confused . need some help PLZ . I have tested the mosfet using a multimeter and its working fine .

You may need a pull down resistor on the gate to discharge the internal gate capacitor. Show us a circuit diagram.
Thanks
Adam

 

[3eprabu]

You may need a pull down resistor on the gate to discharge the internal gate capacitor. Show us a circuit diagram.
Thanks
Adam

Thanks Adam , I added a pull down resister and its working fine .

My question now is , will this pull down resistor effect the PWM signal I'm going to supply to the gate ? I'm planning to build a light dimmer with the mosfet .

Thanks in advance .

 

[3eprabu]

Please link the part# and a diagram to confirm which pins you are using.

Thanks, your help is very much appreciated. . I'm able to controll the mosfet now

 

[3eprabu]

Here is the Datasheet.

EDIT: Look at the internal workings of the mosfet.

Martin

Thanks, your help is very much appreciated. . I'm able to controll the mosfet now

 

[BobK]

The resistor can probably be 100K or even 1Meg, and at that level It will not affect the PWM signal.

Bob

 

[3eprabu]

The resistor can probably be 100K or even 1Meg, and at that level It will not affect the PWM signal.

Bob

Thanks bob . Any idea how to step down 240 v DC to 10 v DC ?

 

[BobK]

I wouldn't. Do you have another source of power?

Bob

 

[Arouse1973]

Thanks Adam , I added a pull down resister and its working fine .

My question now is , will this pull down resistor effect the PWM signal I'm going to supply to the gate ? I'm planning to build a light dimmer with the mosfet .

Thanks in advance .

As Bob kindly chipped in with the answer I agree with Bob.
Adam