isn't a portable oscilloscopeMeasure: wrap around some kitchen aluminium foil and measure capacitance between the foil and each ends. Higher measured vaue belongs to the outer foil.
intresting, i'll try it, but i want test with oscilloscopeEmpirically: hold the capacitor in your hand and touch each lead to the input of an audio amplifier. Higher hum belongs to the outer foil.
don't change nothing with none of my caps....probably my hantek 6022be needs to configured for this type of testing, i hope someone helps meMeasure empirically: connect an oscilloscope probe to each leads. Touch the capacitor body with your finger. Higher mains AC signal belongs to the outer foil.
For this to work you need the input impedance of the oscilloscope to be similar or smaller in magnitude than the reactance of the capacitor at 50/60Hz. A high impedance input will not show any difference.lcsaszar said:Measure empirically: connect an oscilloscope probe to each leads. Touch the capacitor body with your finger. Higher mains AC signal belongs to the outer foil.
none values don't change also.What if you connect the other lead to the GND of the probe? I will try it myself at home. But outer foil is usually marked on wrapped foil capacitors, and the only reason I can imagine is susceptibility to stray electric field (outer foil should be connected to lower impedance point in the circuit: e.g. signal source, GND, in order not to pick up any noise). A test should also be based on this.
too complicated for meLook at video of film capacitors tests with oscilloscope
Are Your Capacitors Installed Backwards? Build this and find out
i don't have guitar amplifier, i'm not just a lucky manand quick test with amplifier
Tone/coupling cap outer foil test - THE EASIEST WAY.
Have a nice day
ops!....i've done measurements without generator....could be this the reason of my failure ? what type of generator ?
For this to work you need the input impedance of the oscilloscope to be similar or smaller in magnitude than the reactance of the capacitor at 50/60Hz. A high impedance input will not show any difference.
The generator is a standard audio or function generator.ops!....i've done measurements without generator....could be this the reason of my faliure ?
what type of generator ?
if yes how must i proceed ?
i tried don't change nothing !!!, why ?The generator is a standard audio or function generator.
Ideally, the frequency should be set as high as possible, except that the practical limit depends on the capacitance value and the generator's output impedance.
Function generators generally come in 50 ohm, sine oscillators can be 600 ohm or any other value.
Anyway, 1kHz should be OK in most cases except if you measure really high capacitance ones, like >1µF
Relying on stray fields caused by the mains frequency is probably one of the worst options: ideally, you should make the test on a ground plane, and use a test frequency visibly different from the mains frequency and its harmonics, to avoid confusions
I just remade a sanity check of the method, and the results are completely unambiguous, even on "difficult" cases, like small boxed caps
Show your setup, indicate the capacitor's value, in short give us all the details: the reason will be immediately apparent, because as I said earlier, the method is extremely robust and reliable, at least when there is indeed an outer foil: if you try to determine a standard ceramic disc capacitor that way, your results will be completely inconclusive for a very good reason....i tried don't change nothing !!!, why ?