Basically, when you specify a coil, you're gonna want to know its inductance, power handling, resonant frequency (cos it's a capacitor too) and its Q factor, which WILL be stated at a given frequency, unless the intended usage frequency is so low that skin effect plays no part in which case the DCR will be given.
You're not going to be using a 10H choke in a microwave oscillator and you're not going to be using a few nanohenries of trace on a PCB to smooth your tube HT.
Inductors should be measured at the frequency of interest.
w
You're not going to be using a 10H choke in a microwave oscillator and you're not going to be using a few nanohenries of trace on a PCB to smooth your tube HT.
Inductors should be measured at the frequency of interest.
w
Unfortunately, when inductors are used in wide band applications, just measuring at a few frequencies is not enough. It's just necessary to model components to match the impedance curve or find the proper inductor by examining at least the whole spectrum of it's intended use.
And I know just the device to do it!
A guy here in town has a wonderful LRC bridge from the late 70s. It's computerized and has a CRT display. Will measure LCR, ESR, dissipation factor, reactance etc. And from 20Hz to 20Khz - up to 10 volts drive.
Very interesting to look at caps, inductors and resistors, too. The better ones are more linear, no doubt about it.
A guy here in town has a wonderful LRC bridge from the late 70s. It's computerized and has a CRT display. Will measure LCR, ESR, dissipation factor, reactance etc. And from 20Hz to 20Khz - up to 10 volts drive.
Very interesting to look at caps, inductors and resistors, too. The better ones are more linear, no doubt about it.
The intended XO is at 200 Hz and the schematic calls for 9mH @ 0.35 ohms. I know a lot of American builders have bought this value iron-cored inductor from Parts Express. Their catalogue simply lists values and the respective prices but mentions nothing about power limits, saturation or XO range. A return email from them only informed me of the price per unit and the cost of shipping to South Africa. They refuse to use small-parcel post and the cost of their method is a prohibitive $168.00. All these inductors stacked on retailers shelves must be designed for some purpose but no info ever seems to accompany them. What do all you serious DIY'ers do. I get the feeling that perhaps the vast majority just close their eyes and ears and use what the supplier sends.
Sy suggested bi-amping. I am working on it and will be back with a bunch more questions but I need to overcome this hurdle first.
Sy suggested bi-amping. I am working on it and will be back with a bunch more questions but I need to overcome this hurdle first.
This is from a datasheet for current-compensated noise suppression chokes from Radiohm. An example of what manufacturers can tell, but often don't want to or don't feel the need to.
They were of the same rated value. What were the exact values? Like any components inductors also have tolerances.
They also have a capacitive component, due to wires running in parallel to form a winding. That explains some of the deviations.
Cores have saturation and remanence that explain most of the rest. And then the capacitive component, the saturation and remanence also deviate from one inductor to another, explaining what remains.
The measurements you made, show less tolerances from one inductor ot another than you should expect from speakers. You should not worry too much about them.
Just a guess. The blue lines come from the air coil the others from the cored ones.
They were of the same rated value. What were the exact values? Like any components inductors also have tolerances.
They also have a capacitive component, due to wires running in parallel to form a winding. That explains some of the deviations.
Cores have saturation and remanence that explain most of the rest. And then the capacitive component, the saturation and remanence also deviate from one inductor to another, explaining what remains.
The measurements you made, show less tolerances from one inductor ot another than you should expect from speakers. You should not worry too much about them.
Just a guess. The blue lines come from the air coil the others from the cored ones.
Yes, the blue lines are from air core, and the others are cored. Also note that in the zoomed on graph there is one additional cored inductor, the curve shape of which more closly matches the air core inductor except for the phase.🙂Also the curves that differ more from the air core have significantly less windings.pacificblue said:This is from a datasheet for current-compensated noise suppression chokes from Radiohm. An example of what manufacturers can tell, but often don't want to or don't feel the need to.
They were of the same rated value. What were the exact values? Like any components inductors also have tolerances.
They also have a capacitive component, due to wires running in parallel to form a winding. That explains some of the deviations.
Cores have saturation and remanence that explain most of the rest. And then the capacitive component, the saturation and remanence also deviate from one inductor to another, explaining what remains.
The measurements you made, show less tolerances from one inductor ot another than you should expect from speakers. You should not worry too much about them.
Just a guess. The blue lines come from the air coil the others from the cored ones.
Inductor values are 2mH.
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