Sup. I've never used MOSFETs, so I want to make sure I'm

>>1093641
yeah that'll probably work. You sure your LED won't explode with 65 mA? That's kind of a lot of current for an LED. Your Ig calculation is wrong, it won't be 12v as the LED will drop probably 1 or 2 volts across it. rotate your picture next time, and >/ohm/

>>1093641
Rg should have one end attached to gate and the other to ground. MOSFET gates float at high impedance so doing this pulls logic 0 to 0 V.

I don't want to derail your thread but would you mind if I also post a mosfet circuit for people to figure out?

>>1093667
I'll take a look

Where are you getting IG from? MOSFET gate looks like a capacitor, your shift register output will charge it up.

>>1093734
Ig is the current I want to draw from the shift register.

File: aqdrwtdrsha.png (37KB, 662x502px) Image search: [Google]

37KB, 662x502px

>>1093746
You don't really have to consider gate current (aside for gate leakage which you can ignore), just make sure that the output voltage from the shift register is higher than the Vt, which should be true as long as the Vdd for the register is appropriate. Also the resistor should probably be grounded on one end but it might stil work regardless.

>>1093760
I do need to consider gate current, or at least the current drawn from the shift register. The 595 can only handle a max of 75mA total I believe. So I only want to pull 6mA per output. Thank you for your help.

>>1094022
What he means. Is the MOSFET gate is floating, it is not connected to the rest of the transistor through a conduction path. This is how the device works, you bias the gate and it allows current flow between source and drain (in switch mode). So current is not going to flow into the gate. (Except for a small leakage current).
Your current draw as indicated by >>1093760 will be through R1