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2bz 17th February 2013 01:23 PM

Old ceramic dogbone capacitor color codes
 
2 Attachment(s)
I just purchased an old tube preamp and am I am having a tough time translating the color codes from these two old ceramic cylindrical capacitor. I find conflicting information on the web and my LC meter tells me something completely different. Could someone take a crack at reading this cap, based upon what you see?

Thanks.
John

turk 182 17th February 2013 03:45 PM

it's a little hard to see the color bands it is the two components that appear different than to the resistors?
if so and if i'm reading the bands correctly it would/should be 250 picofarad.
but looking at these reminds me of encapsulated wire wound inductors which would make them 250 micro henry inductors.what are these selector swicthes intended to do in this amp?

2bz 17th February 2013 03:56 PM

Quote:

Originally Posted by turk 182 (Post 3373562)
it's a little hard to see the color bands it is the two components that appear different than to the resistors?
if so and if i'm reading the bands correctly it would/should be 250 picofarad.
but looking at these reminds me of encapsulated wire wound inductors which would make them 250 micro henry inductors.what are these selector swicthes intended to do in this amp?

The colors as I read them (not much clearer in real life) are silver, brown, green, red. Could you explain how you came up with 250 pF? This rotary swiich selects the input soure. Ie., RIAA, NAB, Tape, 78, etc.

Thanks again.

DUG 17th February 2013 04:04 PM

Quote:

Originally Posted by 2bz (Post 3373579)
The colors as I read them (not much clearer in real life) are silver, brown, green, red. Could you explain how you came up with 250 pF? This rotary swiich selects the input soure. Ie., RIAA, NAB, Tape, 78, etc.

Thanks again.

red =2
green =5
brown =1
silver =10%

25 x 10^1 = 250

Standard resistor (and other devices that chose to follow it) colour code.

turk 182 17th February 2013 04:20 PM

well that just revealed alot when listing color code bands silver gold or nc (no color) are tolerances that are usually listed last.
if they are on the source selector they well could be hi frequency filters.
as far as a schematic you might be hard pressed as it looks like one of the many kit amps of the time based on the williamson circuit.eico heath and knight along with allied are all companies that made and distributed kit amps like this back in the day.this is not to say that with a little archival research you may be able to track down the origins of your vintage treasure.

2bz 17th February 2013 04:40 PM

Quote:

Originally Posted by DUG (Post 3373595)
red =2
green =5
brown =1
silver =10%

25 x 10^1 = 250

Standard resistor (and other devices that chose to follow it) colour code.

Could the silver be the first color band? I.e., is it the temperature coefficient? See about half way down this link:

Color codes for Capacitors

JonSnell Electronic 17th February 2013 07:55 PM

Definately not.
Silver and Gold are exclusively tollerence reading.
Brown and pink are also used.

2bz 17th February 2013 09:02 PM

Quote:

Originally Posted by Harleyjon (Post 3373919)
Definately not.
Silver and Gold are exclusively tollerence reading.
Brown and pink are also used.


Apparently, not according to Color codes for Capacitors.

JonSnell Electronic 17th February 2013 09:09 PM

That was not the capacitor shown in the photo. If it had been that type of, to give it its correct name, CONDENSOR, I would have pointed that out.

DUG 18th February 2013 04:21 AM

Quote:

Originally Posted by 2bz (Post 3373993)
Apparently, not according to Color codes for Capacitors.

I would have to agree that according to Figure 3-23. - Ceramic capacitor color code, the silver could be the first and represent a temperature coefficient.

That would make it

brown =1
green =5
red =2

or 15 x 10^2 = 1500pF at probably 20% tolerance (no band for tolerance)

Learn something every day.

:)

Measure it and tell us what the value is...250pF or 1500pF.

Even a cheap meter can tell the difference.


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