A potentiometer with a resistive load, showing equivalent fixed resistors for clarity.

The potentiometer can be used as a voltage divider to obtain a manually adjustable output voltage at the slider (wiper) from a fixed input voltage applied across the two ends of the potentiometer. This is the most common use of them.
 

The voltage across RL can be calculated by:
V_\mathrm{L} = { R_2 R_\mathrm{L} \over R_1 R_\mathrm{L} + R_2 R_\mathrm{L} + R_1 R_2}\cdot V_s.

If RL is large compared to the other resistances (like the input to an operational amplifier), the output voltage can be approximated by the simpler equation:

V_\mathrm{L} = { R_2 \over R_1 + R_2 }\cdot V_s.

As an example, assume

V_\mathrm{S} = 10\ \mathrm{V}R_1 = 1\ \mathrm{k \Omega}R_2 = 2\ \mathrm{k \Omega}, and R_\mathrm{L} = 100\ \mathrm{k \Omega}.

Since the load resistance is large compared to the other resistances, the output voltage VL will be approximately:

{2\ \mathrm{k \Omega} \over 1\ \mathrm{k \Omega} + 2\ \mathrm{k \Omega} } \cdot 10\ \mathrm{V} = {2 \over 3} \cdot 10\ \mathrm{V} \approx 6.667\ \mathrm{V}.

Due to the load resistance, however, it will actually be slightly lower: ≈ 6.623 V.

One of the advantages of the potential divider compared to a variable resistor in series with the source is that, while variable resistors have a maximum resistance where some current will always flow, dividers are able to vary the output voltage from maximum (VS) to ground (zero volts) as the wiper moves from one end of the potentiometer to the other. There is, however, always a small amount of contact resistance.

In addition, the load resistance is often not known and therefore simply placing a variable resistor in series with the load could have a negligible effect or an excessive effect, depending on the load.

Contact us

Tel: (86) 769 8118 8110
Tel: (852) 8106 7033
Fax: (852) 8106 7099
E-mail: info@kingtronics.com
Skype: kingtronics.sales
MSN: kingtronics-sales@hotmail.com
Web: www.Kingtronics.com

About

Kingtronics International Company was established in 1995 located in Dongguan City of China to handle all sales & marketing for factories located in Chengdu, Sichuan and Zhaoqing, Guangdong, China. In 1990, we established the first factory to produce trimming potentiometer and in 1999 we built up new factory in Zhao Qing, Guangdong. Now with around 850 workers, Kingtronics produce trimming potentiometers, dipped tantalum capacitors, multilayer ceramic capacitors, and diode & bridge rectifier. We sell good quality under our brand Kingtronics, and Kt, King, Kingtronics are our three trademarks. All our products are RoHS compliant, and our bridge rectifier have UL approval. Please visit our Products page, you could please download all our PDF datasheet and find cross reference for our Trimming Potentiometer and capacitors.

Tantalum and Ceramic Capacitors Cross Reference ↓ Download
Diodes & Rectifiers List(PDF: 97KB) ↓ Download
Trimming Potentiometer Cross Reference ↓Download

Meet Kingtronics in Moscow soon
electronicAsia-2019
electronicAsia-2019
Convention and Exhibition Centre,HongKong
Date: 13-16 October, 2019
Booth No.: 5G-C26

Meet Kingtronics in Munich soon
electronica-2020
Electronica-2020
New Munich Trade Fair Centre, Germany
Date: 10-13 November, 2020
Booth No.: To be advised

Archives

Calendar

<< 2019-9 >>

Sun

Mon

Tue

Wed

Thu

Fri

Sat

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30