Hey All,
The book is awesome!
I was wondering, in the first paragraph of ch. 4 page 14 (link below):
http://www.allaboutcircuits.com/vol_3/chpt_4/14.html
It says "An often-used circuit applying the bipolar junction transistor is the so-called current mirror, which serves as a simple current regulator, supplying nearly constant current to a load over a wide range of load resistances."
My confusion is, are they constant current or current limiting? I tried these circuits and from my experiments it looks like it is more of a current limiting device. Say for example I have 10mA going through R_load. If I increased the resistance of R_load, I noticed that the current kept decreasing.
What I was expecting from a constant current device, is to constantly adjust the current through R_load so that it stays at 10mA as I increased the resistance. Is this the right assumption?
On the other hand, if I decreased the resistance of R_load, it would never go passed 10mA which I expected it to be so.
So to me a current mirror is a current limiting device.
I could also be misunderstanding what current limiting and constant current devices are to begin with .
If anyone can clarify I would really appreciate it.
Thanks!
The book is awesome!
I was wondering, in the first paragraph of ch. 4 page 14 (link below):
http://www.allaboutcircuits.com/vol_3/chpt_4/14.html
It says "An often-used circuit applying the bipolar junction transistor is the so-called current mirror, which serves as a simple current regulator, supplying nearly constant current to a load over a wide range of load resistances."
My confusion is, are they constant current or current limiting? I tried these circuits and from my experiments it looks like it is more of a current limiting device. Say for example I have 10mA going through R_load. If I increased the resistance of R_load, I noticed that the current kept decreasing.
What I was expecting from a constant current device, is to constantly adjust the current through R_load so that it stays at 10mA as I increased the resistance. Is this the right assumption?
On the other hand, if I decreased the resistance of R_load, it would never go passed 10mA which I expected it to be so.
So to me a current mirror is a current limiting device.
I could also be misunderstanding what current limiting and constant current devices are to begin with .
If anyone can clarify I would really appreciate it.
Thanks!