Maker Pro
Maker Pro

Hello can somebody tell me, how come 10mA this current source

michael1978

Mar 17, 2012
388
Joined
Mar 17, 2012
Messages
388
The base-emitter voltage of the 2N5401 Q6 is about 0.62V when it begins to turn on. When Q6 turns on it begins to cutoff Q7 so the current in R9 and Q7 is constant at 0.62V/62 ohms= 10mA.
ooohh thank you very much
 

Terry01

Jul 5, 2017
206
Joined
Jul 5, 2017
Messages
206
The base-emitter voltage of the 2N5401 Q6 is about 0.62V when it begins to turn on. When Q6 turns on it begins to cutoff Q7 so the current in R9 and Q7 is constant at 0.62V/62 ohms= 10mA.

I guessed the answer was to do with the transistors before I got to see Audioguru's detailed answer to the question.
I didn't know the exact numbers but I guessed that was where the 10mA reading was coming from.
I am learning :)
 

michael1978

Mar 17, 2012
388
Joined
Mar 17, 2012
Messages
388
I guessed the answer was to do with the transistors before I got to see Audioguru's detailed answer to the question.
I didn't know the exact numbers but I guessed that was where the 10mA reading was coming from.
I am learning :)
yes 10mA audioguru
answer
 

Terry01

Jul 5, 2017
206
Joined
Jul 5, 2017
Messages
206
We will learn a lot from the more experienced guys Michael. I have learned a lot by just reading other peoples posts. :)
 

AnalogKid

Jun 10, 2015
2,893
Joined
Jun 10, 2015
Messages
2,893
Note that the schematic in post #1 has a problem. The high impedance and high compliance 10 mA output point is not the emitter of Q7. It is between the collector of Q7 and ground. If you want the 10 mA to go off and do something like light an LED, that is where to connect it.

ak
 
Top