I made some LED lights for my friend powered by a custom Attiny-85 board, using IRFZ44N MOSFETs to allow current through to ground. However, when plugged in, the MOSFETs allow current through when the gates are low. Some switching is occurring however. Schematic included below...
And yes, I know, no pull up/down resistors. Those didn't seem to work.
Hi,
First off, can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
NOT Fritzy...
You have no current limit resistors for the LEDs.
The IRFZ44N is a N-Ch FET, it is not a logic level MOSFET, the 5V from the attiny will not turn the MOSFET completely ON.
You have the MOSFET connected back to front, the way you have it the internal protection diode is conducting current D to S.
Please use 220R series gate resistors and 10K gate to source resistors.
Also some capacitors around the three pin regulator would also help.
I suggest you read the spec sheet on the reg, to see what is needed, also read up on Arduino MOSFET and LED
Tom.... 
irfz44n.pdf (105 KB)
snuu:
I made some LED lights for my friend powered by a custom Attiny-85 board, using IRFZ44N MOSFETs to allow current through to ground. However, when plugged in, the MOSFETs allow current through when the gates are low. Some switching is occurring however. Schematic included below...And yes, I know, no pull up/down resistors. Those didn't seem to work.
Where on earth did you get that circuit? You have p-channel devices in your fritzing diagram connected
drain-to-ground, as source-followers(*), but mention n-channel IRZ44's which aren't even logic-level? And you have no series resistors on the LEDs either...
You show no capacitors for the voltage regulator, nor any decoupling on the ATtiny (both are mandatory
in any circuit).
(*) You never use source-follower configuration for switching.
Wrong FETs, I used N channel. The final circuit has caps for the regulator, but I will add decoupling caps for the attiny. New schematic (not Fritzing breadboard) will be uploaded.
Here's your bad schematic. I could really use some slack because this is a prototype and I had no clue about logic level MOSFETS before I built it. The problem is that the MOSFETs are allowing current through when no current is being put into the gate.
Hi,
Here is a schematic of how to connect MOSFETs, as mentioned before you have them connected the wrong way, Drain and Source have been interchanged.
In my diag I have included R7 R8 and R9, include them if you are using a single LED for each MOSFET, but if you are using a 12V strip then leave them out.
You should get some response from your LEDs using the IRFZ44N, but it may not be full brightness.
Also note the capacitors around the regulator, this helps with regulation and stability of the regulator.
Tom..... 
Logic level N-channel MOSFET that works well: AOI-514
http://www.digikey.com/product-search/en?keywords=aoi514
I use 32 of them on this board for driving high current LED strips for example:
clip on youtube fading up & down the channels by my son: Arduino Power! - YouTube
Cross Roads Electronics
Thanks for the MOSFET recommendation CrossRoads. The link didn't work. Of course it wasn't hard to find, but just in case others want to find it here is another link (I hope this one works).
I'll likely add some to my next order.
If a MOSFET conducts when the gate is connected to the source, then you've blown the gate-oxide.
Remember MOSFETs are static sensitive and have no protection diodes, so you must take care
handling them.
