A quick review/reminder on OLD resistors

As a review for some, or some new info for others, I thought I'd review the coding scheme for the really old "dog bone" style resistors you may come across--typically in your 1930s era sets.


Just remember this little saying of mine:  "Chances are you've been working on that radio too long, it's probably time for BED".

B.E.D.  Body  End  Dot   The trick to the secret code   

Here's the first example:



Sorry for the lack of color clarity, but you have a majority of the body colored brown, and end painted black and an Orange dot

So, using the trick of BED;  body= brown  end= black  dot= orange.

Remember your resistor color codes?

Brown =  1
Black =   0
Orange= 3


1 0  3

10000

10,000 or 10k ohm resistor is what we have here.




Next one;




We have a red painted body, a yellow blob in the middle and the end that has been dipped in black....


Okay, so what do we have here?  (Besides an old resistor  )

(Quiz time)....  

20K???

I believe that would be 200K

Joe T.

I can never remember how to read those things. I always have to ask. Now I know WHO to ask. Thanks, Doc.

Regards

WC

Dang. I was half asleep. Thanks.

Thanks for sharing that! At least I won't be caught off base when I need to evaluate one of those types.

Now for the answer to our quiz:

"We have a red painted body, a yellow blob in the middle and the end that has been dipped in black..."

Body = Red which = 2

End = Black which = 0

Dot= Yellow which = 4

So....

204


200000

If you said 200,000 OR 200K You would be correct  


PART II


Another thing that throws many for a loop is the use of "M" on old schematics. "M" is the Roman Numeral for 1000. It was not until later "k" was adopted meaning "kilo" or 1000. Today we take for granted M means million. Here lies the problem....

Many times those old "un-updated" '30s era schematics show resistance such as 10M or 100M. This almost always spells confusion for the newbies.   100 million ohms is pretty darn high for a radio circuit??!!!    100 thousand (100k) is not. M=1000 in these cases.

It's another thing you pick-up as you learn.

Just an FYI or review.