Hello,
I am trying to use a BC547B NPN transistor as a switch to control a 5mW red laser, but I can't get it to work.
I believe it is because I have the wrong resistor to control the current on the base.
Does anyone here know how I can calculate R1 in the sketch below?
Please ignore the laser component name (QED123), it is just a side effect of picking a random LED component to symbolize my laser.
I am unfortunately stuck. Have tried random values for R1, but no luck.
BC547, looking at its datasheet, pinout is "unusual" - looking at the face with the leads pointing down it's C-B-E (not E-B-C). Could that be the problem?
It is very strange, I too noticed the pinout and I am pretty sure I have it right.
I also guesstimated the same range as you, but I have had no luck. Tried the following values for R1
39 Ohm
175 Ohm
1K Ohm
10K Ohm
Maybe I managed to blow the transistor... need to switch to another one to double check.
Can't figure out why it's not working. Must be something silly.