I've completed a perf board circuit that uses multiple (three) N channel MOSFETS to control the lighting of three blinking LEDs (high power). The blinking is controlled by a PIC10F200, which has 3 GPIO pins that are used to trigger the separate circuits. I had previously programmed this mcu in machine language and tested it on a breadboard. The mcu and programming is/was working just as intended, as demonstrated by the low power application on the breadboard. The schematic for the "high power" LED circuit comes from Instructables. That schematic and and my 3-up version are attached. Please note that the flashing pattern is such that no 2 LEDs are on or supposed to be on at the same time - the 3 output pins on the PIC have an exclusive time allocation for when they are set high (LED is on) and each pin is set low (BCF) before the next pin is set high (BSF), and so on.

Problem: the PIC programming appears to be working but during each pin's off period, that LED is showing a dimmer, but very recognizable, illumination that mimics the blinking pattern of the pin circuit that is set high at the time. One can follow the rotation of the flashing pattern and determine that the programming is working fine by noting the brightest light that is on. But, as said, the other lights are also illuminated but are somewhat dimmer than the circuit that is currently set to high. The problem is worse at startup and improves with time - changes are very noticeable in 3 minutes or so.

Input V is 13.5V (automotive) and there is a 7805 that provides power to the mcu. For the pullups, I've tried 100kR in place of the 10KR to no effect. Also added 100KR for pulldowns to no effect.

If the bleed over lighting was more random or clearly disconnected from the PIC, I'd be more suspicious of the MOSFETS, et al but since the unwanted illumination is same blinking pattern as the pin currently set to high, seems like it has to be a PIC problem. Internal damage?

Thanks to all in advance.
Larry

 

Why use the 2n2222?
Use a logic level Mosfet. IRLZ44

 

I have no clue what you are trying to do with your driver circuit. All you need is the IRLZ44 mentioned above. You can drive the gate directly from the PIC as long as the switching is slow say less than 1KHz

 

I don't know anything about electronics - so is the Instructables circuit not useful? The PN2222 was used because I had some on hand - something wrong with it?

 

- something wrong with it?

Not one I would use!

 

Try this with IRLZ44

 

Thanks Max, but got some questions: 1) I assume the LED_CONTROL can be a GPIO output of ~5V?; and 2) is this schematic current limiting? Are logic level MOSFETs able to control current with no other components - is there a feedback loop in there somewhere? and 3) LED to be downstream in S (pin 3) side of circuit and D (pin 2) going direct to GND?

 

LED current is usually limited using series resistor.
What is feedback required for ?

 

There was no mention before of controlling current.

 

Sorry guys for not explaining the Instructables circuit in more detail. The R3 is a current sensing resistor and 2 one Ohm in parallel (500 mOhm) will limit the current to about 1A. Also, the original spec for the MOSFET was a Fairchild FQP50N06L and the NPN transistor was a Fairchild 2N5088BU. As you can see, I substituted for those items based on what I had on hand.

 

Circuits from Instructables are notoriously bad.