I have a challenege for you analog guru's out there.
Let's say I have a DC source with some internal impedance (kinda like a battery). This impedance is complex is nature with more than one equiv. C, L and R' inside. Given that this impedance will be on the order of milliohms at any particular frequency:
Does anyone out there know of a simple circuit that could accruately measure the impedance of this source. Keep in mind this is AC impedance. What I am looking for are say curves from 1hz - 10kHz for example.
This is a difficult measurement because the magnitude of the impedance is so small!
Let's say I have a DC source with some internal impedance (kinda like a battery). This impedance is complex is nature with more than one equiv. C, L and R' inside. Given that this impedance will be on the order of milliohms at any particular frequency:
Does anyone out there know of a simple circuit that could accruately measure the impedance of this source. Keep in mind this is AC impedance. What I am looking for are say curves from 1hz - 10kHz for example.
This is a difficult measurement because the magnitude of the impedance is so small!
Hmm... a couple of quick 'duh' questions:
1) If your source is DC, why are you interested in your AC impedances?
2) If your source impedance is known to be on the order of milliohms, then what does the value matter. As long as your input impedance is 1-ohm or more, it'll be significantly larger than your source impedance and your attenuation won't really matter.
1) If your source is DC, why are you interested in your AC impedances?
2) If your source impedance is known to be on the order of milliohms, then what does the value matter. As long as your input impedance is 1-ohm or more, it'll be significantly larger than your source impedance and your attenuation won't really matter.
If you have a quality setup like an Audio Precision, this would
not be a problem, as you can drive the DC source with an
AC signal through a big cap and precisely measure the AC
voltages which appear across the DC source. Even milliohms
would not be particularly daunting. You can insert a known
impedance in series with the AP output, or use its internal
25, 50, or 600 ohm source solely.
If you don't have such a refined measurement apparatus, drive
the DC source through a cap and resistor, but with a big fat
power amplifier, and use a less sensitive, but wide band, AC
voltameter.
not be a problem, as you can drive the DC source with an
AC signal through a big cap and precisely measure the AC
voltages which appear across the DC source. Even milliohms
would not be particularly daunting. You can insert a known
impedance in series with the AP output, or use its internal
25, 50, or 600 ohm source solely.
If you don't have such a refined measurement apparatus, drive
the DC source through a cap and resistor, but with a big fat
power amplifier, and use a less sensitive, but wide band, AC
voltameter.
sreten.
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