Decoding models and values

Model A — These can be simple lines or even dots. In the case of a wirewound resistor, the first line on the left is wider than the others.

• The line, dot, or circle on the left indicates the first digit on the left.
• The second, going to the right, indicates the second digit.
• The third corresponds to the number of zeros to be added to the two preceding digits. Consequently, it shows that no zero should be added if it is black. One zero if it is brown, two if it is red, etc.
• The fourth and last on the right is the tolerance granted to the indicated value. Thus, the resistance can only be lower or higher by 5 %, the indicated value. Silver: 10%. Absence of this fourth circle: 20%.

It should also be known that, here, the color of the body, apart from the preceding indications, has no other significance than this: black body: the said body is not insulated; colored body: the body is insulated.

Model B —

• The first circle on the left: gives the second digit.
• The body itself gives the first digit.
• The second circle gives the number of zeros to add.
• The third circle, on the far right, indicates the tolerance.

Model C — The color (gold, silver, or none) on the left gives the tolerance.

• The color of the body gives the first digit.
• The central spot gives the number of zeros to add.
• The color of the right end gives the second digit.

Model D — Older model that does not indicate the tolerance

• the color of the body indicates the first digit
• that of the end the second digit
• that of the central ring, spot, or dot, the number of zeros to add.

Model E — Ceramic model. The value is given in picofarads (pF), which is equivalent to micromicrofarads

• The left end: the temperature coefficient.
• Second circle: first digit of the value to read.
• Third circle: second digit of the value to read.
• Fourth circle: number of zeros to add.
• Fifth circle: tolerance.
• The color of the body is insignificant, and the service voltage allowed for all ceramic capacitors is 500 volts.

Model F — Ceramic model.

• Circle on the left end: temperature coefficient.
• First dot on the left: first digit of the value.
• Second dot on the left: second digit of the value.
• Third dot: number of zeros to add.
• Last dot on the right: tolerance.

Model G — Ceramic model.
Same reading method as before, in F.

Model H — Ceramic model.
From left to right, the dots successively represent:

• The first digit of the value to read.
• The second digit of the value to read.
• The number of zeros.
• The tolerance.
• The fifth dot, isolated on the right, gives the voltage rating according to the following code: green: 500 volts. Orange: 350 volts and Brown: 150 volts.

Model I — Mica model: value always expressed in picofarads.
The circles are facing downwards, and one reads from left to right, counterclockwise: the red output connection is facing upwards:

• First circle: gives the service voltage.
• Second circle: gives the tolerance.
• Third circle: gives the number of zeros ending the value.
• Fourth circle: gives the third digit of the value.
• Fifth circle: gives the second digit of the value.
• Sixth circle: gives the first digit of the value.

Model J — Paper model: value expressed in picofarads:
The two types, practically identical and represented here, are read similarly: the «four circles» side is held to the left while the «two circles» side is held to the right:

• First circle on the left: first digit of the value.
• Second circle on the left: second digit of the value.
• Third circle: number of zeros to add.
• Fourth circle: tolerance.
• The two circles on the right indicate the peak and service voltages.

It should be noted that the outer casing, represented at the far right of our two J drawings, may nevertheless, in some models, be found on the left after adopting the indicated position.

K — Ceramic model. Found, without temperature compensation, only for capacitors with a fairly high capacitance value:
The three lines are read from left to right, as follows :

• The first on the left gives the first digit,
• the one in the center the second digit
• the one on the right the number of zeros.

Model L — Mica or paper capacitors:
Three different codes exist for these models; they are of:

• Radio Manufacturer Association (abbreviated RMA)
• Joint Army Navy (JAN)
• American War Standards (AWS).

As it is primarily a matter of knowing which code one is dealing with, it is the upper left dot (arrow pointing to the right) that provides the information:
It is black in the JAN code, it is black in the AWS code; can also be silver, it is of a different color for the RMA code and white for the RMA code called «class J».
RMA model, paper or mica: Arrow pointing to the right:

• Upper left dot: first digit of the value to read
• Upper middle dot: second digit of the value to read
• Upper right dot: third digit of the value to read
• Lower left dot: service voltage
• Lower middle dot: tolerance
• Lower right dot: number of zeros to add.

RMA Model, Mica, Class J :

• Upper left dot: white
• Upper middle dot: first digit of the value to read
• Upper right dot: second digit of the value to read
• Lower left dot: service voltage
• Lower middle dot: tolerance
• Lower right dot: number of zeros to add.

JAN or AWS Models, Paper

• Upper left dot: silver
• Upper middle dot: first digit of the value to read
• Upper right dot: second digit of the value to read
• Lower left dot: service voltage
• Lower middle dot: tolerance
• Lower right dot: number of zeros to add.

JAN or WAS, Mica Model :

• Upper left dot: black
• Upper middle dot: first digit of the value to read
• Upper right dot: second digit of the value to read
• Lower left dot: service voltage
• Lower middle dot: tolerance
• Lower right dot: number of zeros to add.

M — Paper Model : Arrow pointing to the right:

• Left dot: first digit of the value to read
• Middle dot: second digit of the value to read
• Right dot: number of zeros to add
• Isolated dot at the bottom, on the right: tolerance
• Isolated dot at the top, on the right: service voltage.

N — Arrow pointing to the right:

• Left dot: first digit of the value to read
• Middle dot: second digit of the value to read
• Right dot: number of zeros to add.

These are older models, giving neither tolerance nor service voltage.