47kΩ is fine.
Sounds like you have the MOSFET's source and drain connections interchanged.
With that, the substrate diode will continually conduct the current, independent of whether the MOSFET is biased on or off.

see attached pin diagram for the FETs if they look correct. i have the the following connected:
nmos: S-ground, G-series resistor to uC's output, D-gate of p-mos and 47kohm resistor.
pmos: S-+12V and other side of 47kohm resistor, G-drain of n-mos and 47kohm resistor, D-LED positive side (high side of load)

the flipped the s & d of p-mos per your previous message and now, lights do not turn on at all even after uC's input.

 

see attached pin diagram for the FETs if they look correct. i have the the following connected:
nmos: S-ground, G-series resistor to uC's output, D-gate of p-mos and 47kohm resistor.
pmos: S-+12V and other side of 47kohm resistor, G-drain of n-mos and 47kohm resistor, D-LED positive side (high side of load)

the flipped the s & d of p-mos per your previous message and now, lights do not turn on at all even after uC's input.

No attachment.

If you flipped s & d and it doesn't light, then it does seem that you had the s & d interchanged.
But if it still doesn't work, then you apparently have another wiring error.
Can you post a picture of the circuit?

 

can you see the circuit i attached here?

 

i have attached another "mosfet pinouts" image here to make sure i have the pins wired correctly

 

i have attached another "mosfet pinouts" image here to make sure i have the pins wired correctly

That all looks okay, so there would still appear to be a wiring error.

Can you post a picture of your actual circuit, showing the wiring?

Measure the voltage at all the nodes for both low and high signal input and post those also.

 

hope you can see clearly! the black aligator clip goes to load's + and white aligator goes to +12v

 

That all looks okay, so there would still appear to be a wiring error.

Can you post a picture of your actual circuit, showing the wiring?

Measure the voltage at all the nodes for both low and high signal input and post those also.

i'm wondering if the pmos i picked is larger than i need? is the n-mos not able to turn the p-mos on and off? whats the theory behind this? i was told to get a pmos based on the current draw from the load (which is 0.5A) , but i ended up buying a bigger one than i needed... did this affect anything?

 

That all looks okay, so there would still appear to be a wiring error.

Can you post a picture of your actual circuit, showing the wiring?

Measure the voltage at all the nodes for both low and high signal input and post those also.

this is what i measured:

at nmos-
vgs=3.3v->0->3.3v keeps going back and forth between 3.3 and 0v like the way i programmed.
vdg-=same as vgs
vds=0.8v->0->0.8v keeps going back and forth between 3.3 and 0v

at pmos-
vdg=0v
vgs=12v
vsd=12v; vds=-12v
no +12v at the load Vdrain

 

The bigger PMOS shouldn't be a problem.

Edit: "vdg-=same as vgs" indicates either a wiring error or a faulty FET with gate and drain shorted.

 

Also if the PMOSFET Vgs=+12V, that is a problem, or do you mean Vsg is +12V?

 

you guys are genius!!! my N-mos was broken! I was messing with this circuit on friday and must have blown this n-mos. after your advise, i replaced thr components and they work amazing. thanks a lot.

 

I was messing with this circuit on friday and must have blown this n-mos.

The gates of MOSFETs are quite static sensitive and will blow if they see a voltage above their maximum (typically 20V), so you need to be careful when handling them.
Shorting the gate to the source until they are soldered in the circuit provides good protection.

 

The gates of MOSFETs are quite static sensitive and will blow if they see a voltage abo ve their maximum (typically 20V), so you need to be careful when handling them.
Shorting the gate to the source until they are soldered in the circuit provides good protection.

oh ok. so just run a whire between gate-source of nmos & pmos?

 

oh ok. so just run a whire between gate-source of nmos & pmos?

Yes, you can just wrap a small bare wire (such as stripped wire-wrap wire) around the two.