Reading old capacitor values
 

Mike wrote in message
...
In the back of Vol. 2 of the RSGB Radio Communication Handbook it shows
two
types of ceramic caps. The first has axial leads and the first color band
is wider and is TC then 1st, 2nd, M, T. The other has radial leads and
has
a dot for the tip then 1st, 2nd, M, T.

I have seen some old small block caps just marcked with pF values.

Mike AA8W

"N_Cook" wrote in message
...
British 1940s components that are driving me dotty
Small rod types with body/end/dot colours
red/red/green
orange/orange/green
yellow/purple/yellow
brown/black/brown

what meaning to the yellow and green multiplier dots ?

and Hunts make, brown cased small block, flat leads, with code oc/3100
impressed into the encapsulation
none of them measuring anything like I think the colours/codes mean


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





The broken one, a bit of the paint with the
green spot , broken away.
Body and end blob , both orange, presumably 33pF
http://home.graffiti.net/diverse:gra.../puffy_cap.jpg
ruler 0.1 inch markings, solid black core material

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Reading old capacitor values
 

N_Cook wrote:

The broken one, a bit of the paint with the
green spot , broken away.
Body and end blob , both orange, presumably 33pF
http://home.graffiti.net/diverse:gra.../puffy_cap.jpg
ruler 0.1 inch markings, solid black core material

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



This thread must have taken a turn that I missed. The device in the
photo sure looks like a resistor !?!

-Bill

Reading old capacitor values
 

Bill M wrote in message
...
N_Cook wrote:

The broken one, a bit of the paint with the
green spot , broken away.
Body and end blob , both orange, presumably 33pF
http://home.graffiti.net/diverse:gra.../puffy_cap.jpg
ruler 0.1 inch markings, solid black core material

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



This thread must have taken a turn that I missed. The device in the
photo sure looks like a resistor !?!

-Bill


My first thought on seeing that solid black core, expecting tubes if caps.
But all of that size and format measured over 30M ohm, if resistors, and
that broken one 500 Meg on an insulation tester. Also very small physical
size , for the time, if they were resistors. Anyone interested in a
microscope view of that core?, i could take such a pic, or any suggestions
for chemistry test ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Reading old capacitor values
 

N_Cook wrote:

My first thought on seeing that solid black core, expecting tubes if caps.
But all of that size and format measured over 30M ohm, if resistors, and
that broken one 500 Meg on an insulation tester. Also very small physical
size , for the time, if they were resistors. Anyone interested in a
microscope view of that core?, i could take such a pic, or any suggestions
for chemistry test ?

Thats a new on for me. So what forms the two sides of the capacitor?
Is there any sort of plating on the black core underneath the paint?

-Bill

Reading old capacitor values
 

Bill M wrote in message
...
N_Cook wrote:

My first thought on seeing that solid black core, expecting tubes if
caps.
But all of that size and format measured over 30M ohm, if resistors, and
that broken one 500 Meg on an insulation tester. Also very small
physical
size , for the time, if they were resistors. Anyone interested in a
microscope view of that core?, i could take such a pic, or any
suggestions
for chemistry test ?

Thats a new on for me. So what forms the two sides of the capacitor?
Is there any sort of plating on the black core underneath the paint?

-Bill


The paint is laid directly on the black stuff. In a x30 microscope it has a
slightly porous structure like scaled down clinker but not regular fine
structure like ferrite slugs.
Some ceramic type materials used in 1954 reference for capacitor
construction were Clineonstatite, Magnesium Titanate, Rutile, Strontium
Titanate, Barium Titanate, Barium-strontium titanate. But what any of them
look like I've no idea.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/