Hello forum :-) For quite some time I've been using transistors (mostly npn) to control all sorts of loads with great results. But this time I ran my head against the wall...
My problem is simple: How can I drive a common cathode led (15v, 150mA) from the Arduino Uno?
Since it's common cathode I guess I have to use a PNP transistor, So I came up with the following schematic: which doesn't work, was the leds are lit regardless of whether the pin is set high or low...
I did a little digging around Google and found the following schematic:
As far as I can read, I'll have to use such setup, but are there anything smarter? my requirements are that the circuit should be able control the led which is 15v, 150mA and be able to do it by analogWrite, so it has to support PWM. I have the BC327 and BC337 transistors on hand already. If I have to use the schematic above, how do I figure out the resistors R2 and R3? :-)
I hope a clever head can shine some light on this ;-)
Best regards Joe.