Res12222 decimal resistor

# **[Res12222 decimal resistor]**

![] Res12222 decimal resistor, named after its circuit structure characteristics.
This adjustable resistor consists of 8 resistor chain units of different levels connected in series.
The eight orders of magnitude are:
x0.1Ω, x1Ω, x10Ω, x100Ω,
x1kΩ, x10kΩ, x100kΩ, x1MΩ.
Each order of magnitude can be configured with jump cap coefficients of 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
The total resistance value Rxy of the resistor module is equal to the sum of the resistance values ​​of each order of magnitude.
The total resistance is derived from the terminals marked x and y on the circuit board.

## **How ​​to use:**

For each order of magnitude gear, follow the "jumper setting icon" on the circuit board. Use the jumper cap to set the required number. The sum of the resistance values ​​​​of each order of magnitude is the total circuit board. The value of the setting.
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## **1. Design description: **

1. During the circuit development and debugging process, some scenarios need to be powered on for actual testing. It is necessary to test the working condition of the circuit under different resistance values. At this time, there is an adjustable resistor, which will Comparatively convenient. A larger adjustable range and higher step accuracy are naturally better.
2. High-precision resistor boxes are too bulky and costly. Today’s chip resistors are also very accurate, low-cost, and small in size, which is conducive to small-size design.
3. A simple design of nine 1 resistors in series with 2*10 pin headers and then a jumper cap will take up more space. The pin headers are not reused, and the number of numbers can also be like 1 2 5 banknotes. Reuse would be better.

## **2. Principle introduction: **

1. What needs to be considered is how to use as few resistors as possible and as few pin headers as possible to use a jump cap to jump out the numbers 0 to 9.
2. A 2*3 double-row needle, if only one jumper is used for selection, the conventional use is to select 3 horizontal positions. In fact, the jumper can be selected vertically, which can add 4 choices and the capacity reaches 7 values. . There are some other similar combinations possible.
3. To achieve a step combination of 0~9k values, you can usually use nine 1k resistors to combine them. In fact, you can also choose from combinations such as 1+2+2+5, etc., just like banknotes. Reduce the number of banknotes and greatly reduce manufacturing costs

## **3. My design: **

How to choose the appropriate combination of resistors, the shape of the pin header, and how to connect the resistor to the pin header to achieve the 10-digit number requirement with a jumper cap are all interesting questions. I took a video to explain.
This open source directly publishes one of my answers. If you are interested, you can try some other combinations.
What I use is a 2*4 pin layout, and the resistor string is a combination of 1+2+2+2+2.
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| Pin1 | pin2 | pin3 | pin4 |
| ---- | ---- | ---- | ---- |
| **A** | **E** | **C* * | **D** |
| **F** | **B** | **A** | **D** |

Demonstration video: bilibili
[[Res12222 Decimal Resistor Works Introduction and Demonstration]]( https://www.bilibili.com/video/BV1Rh411g7oF/)