Since I am an old fart and don't know anything

[Pelliott321]

I found this YouTube very interesting
https://youtu.be/BnR_DLd1PDI

I hope I did not waste your time

[ratbagp]

I did not waste my time. I will have to try this sometime.

His collection of test equipment was astonishing. Why would he need all that stuff?

ray

[brombo]

I think he collects old test equipment. I saw a Tektronix 555 scope which goes back to the 1960's. Nowadays a scope, spectrum analyzer, etc. is something you plug into the usb port on your laptop.

[Pelliott321]

im thinking its not real, something virtual
anyway he is a interesting watch

[ratbagp]

Are there any recommendations for such a usb device? Just sufficient for basic tube stuff and to do a similar test on a capacitor?

ray

[brombo]

Here are a bunch of them -

https://www.amazon.com/usb-oscilloscope/s?k=usb+oscilloscope&page=3

[SoundMods]

This is what pisses me off about internet information. Film capacitors are inherently non-polar as they are NOT electrolytics in that they do not have a formed dielectric.

They are essentially a classic (legacy if you will) capacitor dating from the first experimental Leyden jars -- having a dielectric such as paper or plastic creating a "sandwich" between metal plates.

Metalized film have the "plates" coated on the dielectric material that is wrapped.

That striped-mark on many film capacitors simply indicates the outer-most wrap. Some will say that capacitor orientation in a signal path can make a difference.

Maybe if the cap is a shunt to ground -- the cap then has a built-in shield.

[Pelliott321]

that is exactly what the guy said and he demoed that with an oscope
I it might make a difference to have the outer wrap on the low impedance side for noise reduction

[SoundMods]

that is exactly what the guy said and he demoed that with an oscope
I it might make a difference to have the outer wrap on the low impedance side for noise reduction

The point I was making is that film caps are not polarized and that making that comment is very misleading.

And what would be the low impedance side? Plate or grid? Hmmm.

[Pelliott321]

He said the plate side