Hi,
I am very new to electronics and am trying to understand things from the ground up. I have been using the 'ebook' which is extremely good!
My question today is about the arrangement of the protection diode with a transister when the load is a motor or relay (something which I believe has inductance).
I understand that when the current is suddenly stopped through an inductor the magnetic field will collapse and current will be induced and will flow in the same direction as that of the current that caused the field to grow. Hence inductors resist change in current. This is paraphrasing the ebook.
This all so far makes sense.
Now it makes sense to have a diode to protect a transister when the current through the emitter and collector is prevented from flowing and an inductors field is collapsing. My questions are:
1) why is the protection diode in parrallel, I would have thought it would be in series?
2) why is the diode only preventing reverse current to the original current flow which seems counter intuitive (to me) with respect to the inductor causing current to flow in the same direction as the inductor charging current on magnetic field collapse.
A reference circuit
http://pcbheaven.com/wikipages/Transistor_Circuits/
The ebook section on inductors
http://www.allaboutcircuits.com/vol_1/chpt_15/1.html
Thanks in advance and sorry if this is basic stuff....
Charlie
I am very new to electronics and am trying to understand things from the ground up. I have been using the 'ebook' which is extremely good!
My question today is about the arrangement of the protection diode with a transister when the load is a motor or relay (something which I believe has inductance).
I understand that when the current is suddenly stopped through an inductor the magnetic field will collapse and current will be induced and will flow in the same direction as that of the current that caused the field to grow. Hence inductors resist change in current. This is paraphrasing the ebook.
This all so far makes sense.
Now it makes sense to have a diode to protect a transister when the current through the emitter and collector is prevented from flowing and an inductors field is collapsing. My questions are:
1) why is the protection diode in parrallel, I would have thought it would be in series?
2) why is the diode only preventing reverse current to the original current flow which seems counter intuitive (to me) with respect to the inductor causing current to flow in the same direction as the inductor charging current on magnetic field collapse.
A reference circuit
http://pcbheaven.com/wikipages/Transistor_Circuits/
The ebook section on inductors
http://www.allaboutcircuits.com/vol_1/chpt_15/1.html
Thanks in advance and sorry if this is basic stuff....
Charlie