A sample Power FET Circuit using IRF540 and the 4N35M - any comments

The first proper schematic I have ever drawn of a circuit - and I hungry for any feedback that the experts out there may have.

Briefly, I am driving accessory foglights in my car. I want them only to turn on and off with the microcontroller running the circuit. I have sets of three-wire pins that snap into a fitting on the circuit board, so the VCC / Battery 5v Arduino represents the three pins from Arduino (signal, voltage, ground) to drive the opto-isolated circuit. The 5V in may be expanded to do other things than just this on the board, but I’ve left it there for my own reference. Based on my research this setup should work fine - any input on, say, diode protection or other for running more inductive loads would also be appreciated.

I did not label the capacitor - but it’s a 10nf ceramic capacitor. I did some research and with a proper heatsink the IRF540 will be fine for the amperage on my 12v lighting - for each light. In fact more than adequate.

Thanks so much! I hope I did a decent job!

There are no comments, can you resize your picture?
470 kOm - is it a typo? probably, 470 OHm?
C1 not required;
ground not connected at the input;
LED better to move in series with input, or parallel to load;
100 OHm move in series with pin 5;

Here’s a link to a re-worked schematic. Worked backwards from a circuit I saw that works on a power fet board I bought. Combo of looking @ the schematic and reading the board.


The picasa web albums site allows you to zoom and pan and such. seriously this my first i’ve worked up - i mean i’ve made LED boards and such in fritzing so i can practice coding for pin outputs on a little shield - but this is something a little bigger.