Re: Tek 555 Capacitor Replacement List?


Here is the video and it does seem to work.


On Feb 11, 2019, at 10:31 AM, Colin Herbert via Groups.Io <> wrote:

There is an easy way to identify the outside foil, if it exists, with only common workshop things - I hope most of us have at least one oscilloscope? Just connect the capacitor across the input and grab the cap in your fingers without touching any of the bare wires. Try this with the capacitor connected both ways and the way where the most noise is seen has the outside foil connected to the signal lead. As the meerkat says, "simples".

-----Original Message-----
From: [] On Behalf Of Michael A. Terrell
Sent: 11 February 2019 17:06
Subject: Re: [TekScopes] Tek 555 Capacitor Replacement List?

I saw a project online to build something o identify the outside foil. It may have been Mr. Carson's Lab on Youtube.

Another thing to watch out for: Sprague uses a 2 in a circle for their branding, but some people advertise other brands as Sprague that are missing their branding.

Michael A. Terrell

-----Original Message-----
From: Renée <>
Sent: Feb 11, 2019 11:55 AM
Subject: Re: [TekScopes] Tek 555 Capacitor Replacement List?

beware there are a number of caps that the line does not indicate
outside foil , seems like it is just the side that indicates where to
begin reading the info.
I have a number of newer orange drops where the marker is incorrect.

On 2019-02-11 3:17 a.m., Michael A. Terrell wrote:
It may indicate the outside foil, which is marked by a black line on the Orange Drops, if they are marked. The 715P is designed for pule applications, not coupling so it isn't marked on that series. In some applications it was used as somewhat of a shield, or part of a tuned filter when a wire was wrapped around it to create a crude RF filter.

Here is an example of modern caps with the outside foil marked:


I no longer have any data on those oil filled paper 'Black Beauties' but most paper caps marked the outside foil.

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