This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
3 posts • Page 1 of 1
I have been studying various op-amp circuits and I have come across the current to voltage convertor circuit. I am slightly puzzled by the term "current producing device" in the circuit. Wouldn't there also be some sort of voltage produced across this device's terminals?
You cannot have one with out the other, as far as voltage and current. What your referring to is a "change" in either voltage or current, and the op amp is designed specifically to sense this, but not necessarily the other, [before its too late] and alter the out put accordingly. For example, if you had a long line transmission that needed to keep the voltage above a given volt value, you would use a sense circuit to measure and maintain that exact voltage. On the other hand if you had a sensing circuit that was designed to maintain 80 milli amps to a laser diode at any voltage within the power supply range, you would use a current supply sense op amp. Some things are current sensitive while others are voltage sensitive.
A transistor is a current producing device. In other words, if you change the collector voltage (within it's operating range), the collector current does not change much. A current source is characterized by high output impedance and should produce the same current, regardless of the voltage across it, but real devices have limits. The 1N5305 is a current source diode, which is a FET whose zero gate voltage drain current is controlled and the gate is not accessable.
Users browsing this forum: No registered users and 37 guests