I am reading the book Learning the art of electronics and on a part about diodes, the author pointed out that in characterizing a diode(I, V relation ) there is an unavoidable error due to the ammeter and voltmeter. Two arrangements are given:
- A voltmeter in parallel to series arrangement of a diode and ammeter.
- An ammeter in series to a parallel arrangement of a diode and voltmeter.
Further, the author hints that the value of the voltmeter impedance relative to that of the diode makes one of the arrangements have a lesser error effect than the other.
I understand that in case 2, a voltmeter with an impedance comparable to the load will lead to a significant amount of current going through the voltmeter than the diode(load). Thus the second arrangement is better with a voltmeter of high impedance.
- In what case will the first arrangement be preferred over the other?
- What would be the best arrangement in a case that you do not know the values of instrument impedance's and diode( load ) impedance?
- Based on the impedances of commonly available cheap multimeters, which way should i use to characterize a diode?
Thank you in advance for your answers.