View attachment 65750
Gentlemen, it's pleasure to meet you. I have a question that require's a bit o' theory and some practice.
My coworkers and I have been tasked with finding the active impedance of one of our DC systems. We are assuming that it is net capacitive in behavior. That being said, the circuit is simplified in the attached picture. Our goal is to find the capacitance of this system. Since power up is a hairy mess of random boot-up times, we decided to test this value with a step response. That is to say, we are switching a series resistance in and out of the circuit after it has reached steady state by utilizing a debounced switch and an NFET. We triggered on these events to get some plots of Vc and Itotal with our handy Tek scope. Assuming I can eventually figure out how to get raw excel or CSV data from the waveforms, how might I implement the derived equation shown below so that I can find C?
RL, the resistive load, we know from the steady state Vc and Itotal, easy enough. I can also plot the derivitive of Vc with respect to time on the scope, dandy.
The question is, at what time sample do I determine C? I'm thinking I might need to bust out the differential equations book for greater insight, but can you gents think of a way to get that C value from the raw data?
Gentlemen, it's pleasure to meet you. I have a question that require's a bit o' theory and some practice.
My coworkers and I have been tasked with finding the active impedance of one of our DC systems. We are assuming that it is net capacitive in behavior. That being said, the circuit is simplified in the attached picture. Our goal is to find the capacitance of this system. Since power up is a hairy mess of random boot-up times, we decided to test this value with a step response. That is to say, we are switching a series resistance in and out of the circuit after it has reached steady state by utilizing a debounced switch and an NFET. We triggered on these events to get some plots of Vc and Itotal with our handy Tek scope. Assuming I can eventually figure out how to get raw excel or CSV data from the waveforms, how might I implement the derived equation shown below so that I can find C?
RL, the resistive load, we know from the steady state Vc and Itotal, easy enough. I can also plot the derivitive of Vc with respect to time on the scope, dandy.
The question is, at what time sample do I determine C? I'm thinking I might need to bust out the differential equations book for greater insight, but can you gents think of a way to get that C value from the raw data?
Last edited: