Caps with numbers

[capbuster]

Ok i ordered some caps from a company just has numbers & ohms rating .
The caps are 473k- 630 volts 224k 503k others are 105j 682j 103j .
What would the cap rating be on theses?
One more question please are dc blocking caps same as reg caps ?
Thanks Capbuster.

[ctc17]

473=.047
224=..22
503=.05
105=1
682=.0068
103=.01
k and j are the max voltage, not sure what they reference to

[wa2ise]

Originally Posted by ctc17

473=.047
224=..22
503=.05
105=1
682=.0068
103=.01

It's like resistors, but where the numbers are substituted for the color code. Okay, that was as clear as mud... The system tells how many picofarads are in the cap. Example: 473 is 47 times 10 to the 3rd power, which would give us 47000 picofarads, AKA 0.047 microfarads.

They used actual resistor color code bands on the bumble bee caps. Those black plastic cased wax caps we all replace on sight nowadays. The color code also told how many picofarads.

[ctc17]

After so may years of looking at them they just auto convert in my head. Its like resistor color codes, I automatically see the colors as the value now.

[capbuster]

Thanks . Much help i booked mark this for future ref.
Thanks again. Capbuster.

[Reece]

I grew up in the era when caps (condensers!) were printed with their REAL readings instead of this modern code stuff. They said .05 mfd., .001 mfd., .00025 mfd., and so on.

When I dove back into radio a number of years ago I found the new (and confusing to me) system of numbering. Here's my "caveman" way of managing it, which you may or may not find useful.

Take a cap marked 473.
The first two digits are the significant digits of the rating. Write them down.
The last digit is the number of zeros that follow.
So you have 47000 picofarads (back in the day we called them micromicrofarads or mmfd.)
Now, to get to microfarads, move the decimal point (always) six places to the left and you have .047000, and tossing the useless zeros, .047 mfd.

I told you it was "caveman."

[capbuster]

Best explanation so far . I must be a neanderthal .
Thanks Capbuster.

[capbuster]

A question please? Ordered a bunch of caps. Only thing they did not have was a .075 mfd. What would be a close sub, over, or under size. by 10%
Thanks capbuster. Iam not very math smart.

[rojoknox]

Greetings from FixitLand!

Originally Posted by capbuster

A question please? Ordered a bunch of caps. Only thing they did not have was a .075 mfd. What would be a close sub, over, or under size. by 10%
Thanks capbuster. Iam not very math smart.

I checked Just Radios <http://www.justradios.com/orderform.html> but .075 uF isn't one of the "vintage" values they stock. It shouldn't be a big deal to use either .068 or .082 uF, both standard values. If you've GOTTA have .075 uF, parallel a .068 and .005 to make .073, or .047 and .027 (or .056 and .018) to get .074. Just Radios has .07 uF caps, to which you could parallel a .005 uF to hit .075 right on the nose (notwithstanding the caps' tolerances). But it shouldn't be *that* critical.

Take care,
--
J. E. Knox 'The Victor Freak'

[Reece]

I'm with rojoknox...when you consider the old caps were probably within 20% of rating, anything between .06 and .09 would do.

[capbuster]

Thanks, really do. Working on old crosley, Only cap left to install. Resistors next
Having fun

[Reece]

Resistors may be OK. I usually only replace them if they are obviously burnt or way way off value. In many circuits it doesn't matter much. Often the stressed ones are the ones that carried a lot of current, like the one between sections of the electrolytics in radios without field coils, then I like to go up one wattage size on that. 20% off could have been what they were when they were almost new. If after a long test run it plays nice and doesn't make sparks and smoke....