Hello everybody
I have a problem in a project I'm working on these days.
The thing I'm doing is, there is a current transformer that senses the leakage current,
the current induced in the current transformer is low (100mA max), and I need to use
this current to trigger voltage comparators (IC: LM311), three comparators each works
at a different voltage.
And for this I needed a current to voltage circuit, and what I did is that I used a
transistor (2N2222), the sensed current (AC) goes into Base, and a DC voltage source
applied at the Collector, and the Emmiter works as a common ground, R(Base) = 10
ohms, R(Collector) = 100 ohms, when Base current increases there will be a voltage
drop at the Collector, and I use this Collector voltage to apply on the voltage
comparators, I tried this circuit with the current transformer and it didn't work. So I
tested this method but used a function generator instead of the current transformer for
testing, and found that there is no voltage drop till the base voltage reaches 1.3V, and
the actual voltage that comes from the current transformer is less than 0.3V, even that I
tried to make the current from the function generator the same as the current from the
current transformer, it works but the voltage is higher than the voltage in the current
transformer.
Please help me to solve this problem, even if it mean to use any method.
I tried to explain it as good as possible, and sorry for my English I'm not good.
Thank you.
I have a problem in a project I'm working on these days.
The thing I'm doing is, there is a current transformer that senses the leakage current,
the current induced in the current transformer is low (100mA max), and I need to use
this current to trigger voltage comparators (IC: LM311), three comparators each works
at a different voltage.
And for this I needed a current to voltage circuit, and what I did is that I used a
transistor (2N2222), the sensed current (AC) goes into Base, and a DC voltage source
applied at the Collector, and the Emmiter works as a common ground, R(Base) = 10
ohms, R(Collector) = 100 ohms, when Base current increases there will be a voltage
drop at the Collector, and I use this Collector voltage to apply on the voltage
comparators, I tried this circuit with the current transformer and it didn't work. So I
tested this method but used a function generator instead of the current transformer for
testing, and found that there is no voltage drop till the base voltage reaches 1.3V, and
the actual voltage that comes from the current transformer is less than 0.3V, even that I
tried to make the current from the function generator the same as the current from the
current transformer, it works but the voltage is higher than the voltage in the current
transformer.
Please help me to solve this problem, even if it mean to use any method.
I tried to explain it as good as possible, and sorry for my English I'm not good.
Thank you.