How to measure transistor current?

[menirva]

I'm designing a current source. In reality, how to measure the current flow thru E to C of the PNP, with ammeter? Is it the same with NPN?

Cut off the wire from (+ve VDC) to the E, then connect probe A to (+ve VDC), and probe B to the E? But i get different value displayed, when compare to the simulation reading.

Thanx!






p/s: sorry, ignore this post, i got it already, just a minor mistake.

 

[Hero999]

I know you've got it but, for anyone that doesn't, it's the same as measuring current in any situation. Just break the circuit and connect the ammeter in series with it.

That isn't a very good constant current source, the current will vary hugly depending on the power supply and transistor's gain.

A better onstant current source can be made from an LM317, see the datasheet.