Current Limiter, can someone troubleshoot this circuit?
There is another way to implement a current sink when you have a regulated voltage available. It often works well enough. You can consider using it since you have 10V available.



The base current will be IC/beta. Choose R2 and R3 so that the current through them is 10x the base current or more.

It is a good idea to keep Vemitter at around 0.5V or more. But the collector of Q1 can't be lower than Vemitter, so keep that in mind. I have used this for driving blue or white LED's from 3.3V or from a Li battery.