- #1
dnyberg2
- 125
- 2
The attached circuit is not my design but I need to understand it completely.
This is a circuit that supplies power to a sensor.
When S1 is closed the power is removed from RL.
What is the purpose of D1?
In General, what happens if R1 were to short?
I know the base would be subjected to the max avail current of about 1 mA,
but would that ruin the BJT in this config or could it lead to the death of the BJT eventually?
In general, what is the failure mode of a BJT if the base is over driven?
Can one expect the collector & emitter to eventually short?
In this case Q1 is just a switch either in or not in saturation right?
So R4 and R2 rule how much current can get to the sensor even if shorted or does R1 play in that role? In my mind there is no voltage divider on the base so the base gets the full supply voltage. The CE junction is either full on or full off and delivery of current is subject to the datasheet limits of the BJT yes?
Thanks in advanced.
This is a circuit that supplies power to a sensor.
When S1 is closed the power is removed from RL.
What is the purpose of D1?
In General, what happens if R1 were to short?
I know the base would be subjected to the max avail current of about 1 mA,
but would that ruin the BJT in this config or could it lead to the death of the BJT eventually?
In general, what is the failure mode of a BJT if the base is over driven?
Can one expect the collector & emitter to eventually short?
In this case Q1 is just a switch either in or not in saturation right?
So R4 and R2 rule how much current can get to the sensor even if shorted or does R1 play in that role? In my mind there is no voltage divider on the base so the base gets the full supply voltage. The CE junction is either full on or full off and delivery of current is subject to the datasheet limits of the BJT yes?
Thanks in advanced.