outside foil capacitor foil testing

[desertmouth90]

I am currently building a new Dumble 3rd Gen amp and I want orientate my orange drops correctly.

The only thing is my Osciliscope only goes down the 10mv so doesnt show the sensitivity, could I out a signal through the cap to get the require sine wave?

Thanks!

[pjd3]

Good luck with that Desertmouth.

Sometimes my scope (Siglent) doesn't give me the resolution or detail to tell which lead goes to the outer foil. Strangely, whenever I test for this on the Mallory 150's its much more apparent than on other brands or types. Could just be the day, (or me).

I've often wondered if bringing the cap in proximity to say, an idling transformer would give a better waveform profile to judge from. But let's see what the others have to say.

Best
phil D

[desertmouth90]

That is not a bad idea at all actually. I will try my laptops transformer later when I get in.

All I can think about is this and im sat at work!!!

[pjd3]

Oh you are not alone. I share that same disease.

As a matter of fact, I just now took a blank Twin Reverb chassis into my works machine shop and bored out the holes for the tube sockets - stereo amp, 4 octals and 6 9-pin. Luckily, my job is very cool and some of the big guys in here are guitar players. I couldn't ask for a better work environment!

Think on Brother, think on.

Phil D

[Stevem]

A cap meter and a small piece of foil to wrap around the cap body is an easier way to go.

[desertmouth90]

A cap meter and a small piece of foil to wrap around the cap body is an easier way to go.

How does this work? I’ve not heard of this method before

[pjd3]

Perhaps the capacitance would be measured between the aluminum foil and each cap lead? and the measurement with the highest capacitance sites the lead attached to the outer foil? I'm just thinking out loud hear but for sure, I'd also be very interested in how this works. I'll probably try it as soon as I get home.

Best,

Phil D.

[martin manning]

From: https://www.aikenamps.com/index.php/whe ... capacitors

"If you cannot see a large enough induced AC signal by holding the capacitor between your fingers, place the capacitor on top of an AC line cord (that is plugged into the mains wall socket, of course!) instead of holding it between your fingers and you will see a larger signal on the scope."

[desertmouth90]

From: https://www.aikenamps.com/index.php/whe ... capacitors

"If you cannot see a large enough induced AC signal by holding the capacitor between your fingers, place the capacitor on top of an AC line cord (that is plugged into the mains wall socket, of course!) instead of holding it between your fingers and you will see a larger signal on the scope."

Still doesn’t show any results

[B Ingram]

... place the capacitor on top of an AC line cord (that is plugged into the mains wall socket, of course!) ...

Still doesn’t show any results

Don't use a switch mode power supply "brick" like that.

Plug a guitar amp into the wall, and turn the amp on. Now put the cap on the power cord. We hope for there to be enough AC current-draw to create a field for the cap to pickup up (and display via the scope).

[syscokid]

I don’t have a O-scope. I use the method on the following YouTube video, but I plug into a gained out fuzz pedal first, which is then plugged into an amp. Works very well!

https://youtu.be/1xjj5E4o0Uo?si=bDnkAGNkKprGXU1F