G'day Guy's,
Rotten weather here today so spent some time up in the shed and with that 4 pin zif connector I got for my touch screen module being so small it was time to fit one of my desktop magnifiers out with some led's for a low DC voltage light. I used commanda's circuit 4 which was just 2 resistors, a BC547 transistor and a 2n7000 fet. For now I've just hooked it up to a 12 volt DC plug pack and put a on/off switch and it does work nicely.
@ 12 volts it draws about 143mA of current which is only 8.9mA for each led. I used a 1 meg ohm resistor for Rg and a 12 ohm resistor for Rs. One thing I did find with the voltage @ 17 volts the current shot up 430mA but by using that 12 volt plug pack will ensure the led's don't get too much current.
Cheers Bryan