Talk:Circuit Idea/Building a BJT Current Mirror

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Here is the building "scenario" that my students (group 67b) and I were using during Lab 3 to build the popular circuit of BJT current mirror. Circuit-fantasist (talk) 13:22, 28 April 2008 (UTC)



Contents

[edit] Lab 3: "Inventing" a BJT current mirror

Tuesday, April 08, 2008, 16.45 h

[edit] A voltage divider sets the input current

Setting the input current by a voltage divider (on the whiteboard).
Mounting and investigating the cirrent mirror circuit on a prototyping printed circuit board (PCB).


[edit] A true diode sets the input current

Trying to add a true diode in the current-setting part...
Adding correctly a true diode in the current-setting part.
The circuit mounted on the PCB.


[edit] A base-emitter transistor "diode" sets the input current

[edit] Replacing the true diode by a base-emitter transistor junction

Setting the input current by a base-emitter transistor "diode".
But there is something wrong in this solution...


[edit] A problem appears

[edit] A negative feedback transistor "diode" sets the input current

[edit] Drawing the diagram on the whiteboard

Setting the input current by a negative feedback transistor "diode".


[edit] Building the circuit on a PCB

Mounting a true current mirror on a prototyping PCB.


[edit] Investigating the circuit

The negative feedback is no connected.
The negative feedback (the green wire) is connected.


[edit] Resources

How to Reverse Current Direction is another Circuit idea story about basic current mirror.
Current mirrors is a popular exposition of the current mirror topic written by the well-known web author Tony Kuphaldt

<<< contents - Group 64a - Group 65a - Group 66a - Group 67a - Group 68a - page stage Development stage: 25% (as of {{{2}}}) >>>


<<< Group 64b - Group 65b - Group 66b - Group 68b >>>
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